Low-Level Radioactive Waste Disposal

NUCLEAR REGULATORY COMMISSION

10 CFR Parts 20 and 61

[NRC-2011-0012; NRC-2015-0003]

RIN 3150-AI92

Low-Level Radioactive Waste Disposal

AGENCY:

Nuclear Regulatory Commission.

ACTION:

Proposed rule.

SUMMARY:

The U.S. Nuclear Regulatory Commission (NRC) is proposing to amend its regulations that govern low-level radioactive waste (LLRW) disposal facilities to require new and revised site-specific technical analyses, to permit the development of site-specific criteria for LLRW acceptance based on the results of these analyses, to facilitate implementation, and to better align the requirements with current health and safety standards. This proposed rule would affect LLRW disposal licensees or license applicants that are regulated by the NRC or the Agreement States.

DATES:

Submit comments on the proposed rule by July 24, 2015. Submit comments specific to the information collection aspects of this proposed rule by May 26, 2015. Comments received after these dates will be considered if it is practical to do so, but the NRC is able to ensure consideration only for comments received on or before these dates.

ADDRESSES:

You may submit comments by any of the following methods (unless this document describes a different method for submitting comments on a specific subject):

•

Federal rulemaking Web site:

Go to

http://www.regulations.gov

and search for Docket ID NRC-2011-0012. Address questions about NRC dockets to Carol Gallagher; telephone: 301-492-3668; email:

Carol.Gallagher@nrc.gov.

For technical questions, contact one of the individuals listed in the

FOR FURTHER INFORMATON CONTACT

section of this document.

•

Email comments to: Rulemaking.Comments@nrc.gov.

If you do not receive an automatic email reply confirming receipt, then contact us at 301-415-1677.

•

Fax comments to:

Secretary, U.S. Nuclear Regulatory Commission at 301-415-1101.

•

Mail comments to:

Secretary, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, ATTN: Rulemakings and Adjudications Staff.

•

Hand deliver comments to:

11555 Rockville Pike, Rockville, Maryland 20852, between 7:30 a.m. and 4:15 p.m. (Eastern Time) Federal workdays; telephone: 301-415-1677.

For additional direction on obtaining information and submitting comments, see “Obtaining Information and Submitting Comments” in the

SUPPLEMENTARY INFORMATION

section of this document.

FOR FURTHER INFORMATION CONTACT:

Gary Comfort, telephone: 301-415-8106, email:

Gary.Comfort@nrc.gov

; or Andrew Carrera, telephone: 301-415-1078, email:

Andrew.Carrera@nrc.gov.

Both of the Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

SUPPLEMENTARY INFORMATION:

Excutive Summary

A. Need for the Regulatory Action

The U.S. Nuclear Regulatory Commission (NRC) is proposing to amend its regulations that govern low-level radioactive waste (LLRW) disposal facilities to require new and revised site-specific technical analyses and to permit the development of criteria for LLRW acceptance based on the results of these analyses. These amendments would ensure that LLRW streams that are significantly different from those considered during the development of the current regulations (

i.e.,

depleted uranium and other unanalyzed waste streams) can be disposed of safely and meet the performance objectives for land disposal of LLRW. These amendments would also increase the use of site-specific information to ensure performance objectives are met that are designed to provide protection of public health and safety. This proposed rule would affect LLRW disposal licensees or license applicants that are regulated by the NRC or the Agreement States.

B. Major Provisions

Major provisions of the proposed rule include changes to:

• Revise the existing technical analysis for protection of the general population to include a 1,000-year compliance period;

• Add a new site-specific technical analysis for the protection of inadvertent intruders that would include a 1,000-year compliance period and a dose limit;

• Add new analyses that would include a 10,000-year protective assurance period and annual dose minimization target;

• Add a new analysis for certain long-lived LLRW that would include a post-10,000-year performance period;

• Add new analyses that would identify and describe the features of the design and site characteristics that provide defense-in-depth protections;

• Add a new requirement to update the technical analyses at closure; and

• Add a new requirement to develop site-specific criteria for the future acceptance of LLRW for disposal based on either the results of these technical analyses or the existing LLRW classification requirements.

C. Costs and Benefits

The NRC prepared a draft regulatory analysis to determine the expected quantitative costs and benefits of the proposed rule, as well as qualitative factors to be considered in the NRC's rulemaking decision. The analysis concluded that the proposed rule would result in net costs to the industry and the NRC. The key findings of the analysis are as follows:

• Cost to the Industry. The proposed rule would result in an average implementation cost per licensee of $1,000,000, followed by an estimated annual cost of $4,000. Overall, the industry will incur an estimated implementation cost of $4 million, followed by an estimated annual cost of $16,000.

• Cost to the Agreement States. The proposed rule would result in additional costs to the Agreement States with all costs resulting from implementation. On average, each Agreement State would incur an estimated implementation cost of $525,000. Overall, the Agreement States will incur an estimated implementation cost of $2.1 million.

• Cost to the NRC. The NRC would incur an implementation cost for drafting and implementing a final rulemaking based on the proposed rule. This cost is estimated to be $333,000. Because the NRC does not have any LLRW disposal licensees, no annual NRC cost is expected. The NRC would also incur an estimated implementation cost of $216,000 for drafting a final guidance document based on the final rule.

The regulatory analysis also considered, in a qualitative fashion, direct benefits that would accrue and the indirect benefits from risks that could be avoided if the NRC adopted the rule. The principal qualitative benefits of the proposed action would include: (1) Ensuring that LLRW streams that are significantly different from those considered during the development of the current regulations can be disposed of safely and meet the performance objectives for land disposal of LLRW; (2) facilitating the use of site-specific

information and up-to-date dosimetry methodology in site-specific technical analyses to ensure public health and safety is protected; and (3) promoting a risk-informed regulatory framework that specifies what requirements need to be met and provides flexibility to a licensee or applicant with regard to what information or approach they use to satisfy those requirements.

The draft regulatory analysis concludes that the proposed rule should be adopted because the proposed regulatory initiatives enhance public health and safety by ensuring the safe disposal of LLRW that was not analyzed in the regulatory basis for the original part 61 of Title 10 of the

Code of Federal Regulations

(

e.g.,

large quantities of depleted uranium). For more information, please see the draft regulatory analysis (Accession No. ML14289A158 in the NRC's Agencywide Documents Access and Management System).

Table of Contents

I. Obtaining Information and Submitting Comments

A. Obtaining Information

B. Submitting Comments

II. Background

A. Existing Regulatory Framework

B. Low-Level Radioactive Waste Classification System

C. Previous Public Interactions

III. Discussion

A. What action is the NRC taking?

B. Who would this action affect?

C. Why do the regulatory requirements need to be revised?

D. When would this rule become effective?

E. What LLRW streams are affected by this proposed rule?

F. What are site-specific technical analyses?

1. Performance Assessment

2. Intruder Assessment

3. Performance Period Analyses

4. Defense-in-Depth Analyses

5. Site Stability Analyses

G. Updated Safety Case and Technical Analyses for Closure

H. What options were considered for selecting approach and timeframes and what is the NRC's preferred option?

1. Considerations Made in Developing Options

2. Options Considered

3. NRC Proposed Option

I. Why are the 1,000-year compliance period and 10,000-year protective assurance period appropriate?

J. Why is a 5 milliSievert per year (500 mrem per year) target appropriate for dose minimization during the protective assurance period?

K. What are waste acceptance criteria (WAC)?

1. Options Considered

2. NRC Proposed Option

L. What other changes are proposed?

1. Adding New Definitions to 10 CFR 61.2 and Updating Concepts in 10 CFR 61.7

2. Implementing Changes to Appendix G to 10 CFR Part 20 To Conform to Proposed LLRW Acceptance Requirements

3. Modifying the Site Suitability Requirements in 10 CFR 61.50 To Be Consistent With the Proposed Analyses Framework

4. Updating the Dose Calculation System Used in 10 CFR Part 61

5. Implementing the Safety Case in 10 CFR Part 61

M. What guidance documents will be available?

N. Are there any cumulative effects of regulation associated with this proposed rule?

O. Request for Additional Public Comments

P. What should I consider as I prepare my comments to submit to the NRC?

IV. Discussion of Proposed Amendments by Section

V. Criminal Penalties

VI. Agreement State Compatibility

VII. Plain Writing

VIII. Voluntary Consensus Standards

IX. Draft Environmental Assessment and Draft Finding of No Significant Environmental Impact

X. Paperwork Reduction Act Statement

XI. Regulatory Analysis

XII. Regulatory Flexibility Certification

XIII. Backfitting

I. Obtaining Information and Submitting Comments

A. Obtaining Information

Please refer to Docket ID NRC-2011-0012 when contacting the U.S. Nuclear Regualtory Commission (NRC) about the availability of information for this action. You may obtain publicly-available information related to this action by any of the following methods:

•

Federal Rulemaking Web site:

Go to

http://www.regulations.gov

and search for Docket ID NRC-2011-0012.

•

NRC's Agencywide Documents Access and Management System (ADAMS):

You may obtain publicly-available documents online in the ADAMS Public Documents collection at

http://www.nrc.gov/reading-rm/adams.html.

To begin the search, select “

ADAMS Public Documents

” and then select “

Begin Web-based ADAMS Search.

” For problems with ADAMS, please contact the NRC's Public Document Room (PDR) reference staff at 1-800-397-4209, 301-415-4737, or by email to

pdr.resource@nrc.gov.

The ADAMS accession number for each document referenced (if it is available in ADAMS) is provided the first time that it is mentioned in the

SUPPLEMENTARY INFORMATION

section.

•

NRC's PDR:

You may examine and purchase copies of public documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852.

B. Submitting Comments

Please include Docket ID NRC-2011-0012 in your comment submission.

The NRC cautions you not to include identifying or contact information that you do not want to be publicly disclosed in your comment submission. The NRC will post all comment submissions at

http://www.regulations.gov

as well as enter the comment submissions into ADAMS. The NRC does not routinely edit comment submissions to remove identifying or contact information.

If you are requesting or aggregating comments from other persons for submission to the NRC, then you should inform those persons not to include identifying or contact information that they do not want to be publicly disclosed in their comment submission. Your request should state that the NRC does not routinely edit comment submissions to remove such information before making the comment submissions available to the public or entering the comment into ADAMS.

II. Background

A. Existing Regulatory Framework

The NRC's licensing requirements for the disposal of commercial low-level radioactive waste (LLRW) in near-surface disposal facilities can be found in part 61 of Title 10 of the

Code of Federal Regulations

(10 CFR), “Licensing Requirements for Land Disposal of Radioactive Waste.” The NRC adopted 10 CFR part 61 on December 27, 1982 (47 FR 57446). The existing LLRW disposal facilities are located in and licensed by Agreement States, and those Agreement States have incorporated many of the requirements in current 10 CFR part 61 into their corresponding regulations and as license conditions.

The current 10 CFR part 61 emphasizes an integrated systems approach to the disposal of commercial LLRW, including site selection, disposal facility design and operation, LLRW characteristics, and disposal facility closure. To reduce reliance on institutional controls, the current 10 CFR part 61 emphasizes passive (

e.g.,

site stability) rather than active systems to limit and retard the releases of LLRW to the environment. This integrated systems approach is similar to the defense-in-depth concept that has been well known for some time for the NRC's nuclear reactor safety design and licensing activities. However, defense-in-depth is not explicitly discussed in the existing 10 CFR part 61 regulations. Currently, the defense-in-depth concept is implicitly contained in the 10 CFR

part 61 regulations (

e.g.,

requiring that the disposal site design complement and improve upon the ability of the site's natural characteristics to ensure the performance objectives will be met; imposing concentration limits on waste that presents a higher hazard through the waste classification requirements; requiring the segregation of unstable waste from waste that presents a larger hazard and should be stable for proper disposal; imposing requirements on wasteform and packaging characteristics; and requiring the use of barriers to intrusion for wastes that will not decay to levels which present an acceptable hazard to an intruder within 100 years).

Subparts of the existing 10 CFR part 61 cover general provisions and procedural licensing matters; performance objectives; technical requirements for near-surface disposal; financial assurance; state and tribal participation; and records, reports, tests, and inspections. The regulations cover all phases of near-surface commercial LLRW disposal from site selection through facility design, licensing, operations, closure, postclosure stabilization, and the end of active institutional controls. The overall philosophy that underlies the regulatory requirements of 10 CFR part 61 is provided in 10 CFR 61.7, “Concepts.”

The following are key provisions in current 10 CFR part 61:

• Standards for: (1) Protection of the general population in 10 CFR 61.41, “Protection of the general population from the releases of radioactivity;” (2) protection of an inadvertent intruder in 10 CFR 61.42, “Protection of individuals from inadvertent intrusion;” (3) protection of individuals during facility operations in 10 CFR 61.43, “Protection of individuals during operations;” and (4) site stability in 10 CFR 61.44, “Stability of disposal site after closure.” These standards are collectively known as the “Performance Objectives” in subpart C of 10 CFR part 61.

• Specification of the minimum geologic and geomorphic characteristics for an acceptable near-surface LLRW disposal site in 10 CFR 61.50, “Disposal site suitability requirements for land disposal.”

• A LLRW classification system (LLRW being categorized as Class A, Class B, Class C, or greater-than-Class C) for commercial LLRW in 10 CFR 61.55, “Waste classification,” based on the concentration of certain radionuclides.

• Specification of the LLRW characteristics in 10 CFR 61.56, “Waste characteristics,” that commercial LLRW forms must meet to be acceptable for disposal.

• Requirements for caretaker oversight in the form of institutional controls of LLRW disposal facilities in 10 CFR 61.59, “Institutional requirements,” for a period of 100 years following facility closure.

Currently, to grant a license, the NRC must conclude that there is reasonable assurance that the performance objectives will be met. To demonstrate that a license applicant will meet these performance objectives, 10 CFR part 61 license applicants need to prepare the analyses required by 10 CFR 61.13, “Technical analyses.”

To demonstrate that the general population is protected from releases of radioactivity, license applicants are required to prepare an analysis of exposure pathways leading to potential radiological doses to the general population. The current 10 CFR part 61 does not impose a specific performance timeframe for use in the analysis to protect the general population, and there are currently differences among Agreement States regarding the analysis timeframe. For example, some Agreement States have required licensees to analyze the disposal facility for only 500 years, while others have required analyses to the peak dose. For certain long-lived LLRW, a shorter timeframe for the analysis could result in a situation where the long-term impacts from the disposal of long-lived LLRW are not adequately identified in a licensee's analysis. Conversely, the increasing uncertainties associated with very long timeframes could diminish the value of the information generated with technical analyses for applicants, regulators, and other stakeholders. The NRC has drafted this proposed rule to balance the consideration of the risks from disposal of long-lived LLRW with significant uncertainties that may be associated with long-term analyses.

License applicants must also demonstrate that potential inadvertent intruders into the LLRW disposal facility will be protected. Inadvertent intruders might occupy the site at any time after institutional controls over the LLRW disposal facility are no longer effective and may not be aware of the radiation hazard from the LLRW. Under the current regulations, protection of inadvertent intruders is demonstrated by compliance with the LLRW classification (10 CFR 61.55) and segregation requirements (10 CFR 61.52, “Land disposal facility operation and disposal site closure”), and by providing adequate barriers to inadvertent intrusion. The NRC developed the LLRW classification requirements as part of the original 10 CFR part 61 rulemaking. Explicit dose limits for an inadvertent intruder are not currently provided in 10 CFR part 61 because an intruder dose assessment is not required, but the LLRW classification concentration limits for radionuclides, in tables 1 and 2 of 10 CFR 61.55, were based on a dose of 5 milliSieverts per year (mSv/yr) (500 millirem per year (mrem/yr)) to an inadvertent intruder. The LLRW classification tables were developed assuming that only a fraction of the LLRW being disposed would approach the LLRW classification limits (note that the dose to an intruder exposed to a large volume of disposed LLRW at the classification limits could exceed 5 mSv/yr (500 mrem/yr)). By complying with the LLRW classification and segregation requirements, an inadvertent intruder will be protected if the underlying assumptions are not violated.

In the existing 10 CFR part 61 regulations, 10 CFR 61.13(a) through (d) require the technical analyses needed to demonstrate that the performance objectives are met. The regulations in 10 CFR part 61 are risk-informed and performance-based, and ensure public health and safety are protected in the operation of any commercial LLRW disposal facility. Applicants can demonstrate how their proposals meet the respective performance objectives for the specific near-surface disposal method selected (47 FR 57446). The NRC is proposing to modify the current regulations to ensure that LLRW streams that are significantly different than those considered in the development of the existing 10 CFR part 61 are adequately considered during the licensing of LLRW disposal facilities, to require licensees to explicitly identify how disposal site characteristics and design provide defense-in-depth, and to ensure that the 10 CFR part 61 performance objectives will be met for disposal of those LLRW streams.

B. Low-Level Radioactive Waste Classification System

The NRC developed current 10 CFR part 61 based on assumptions regarding the types of LLRW likely to go into a commercial disposal facility. These were based on a survey of LLRW generators and the results were published in 1982 in NUREG-0945, “Final Environmental Impact Statement on 10 CFR part 61, `Licensing Requirements for Land Disposal of Radioactive Waste' ” (ADAMS Accession Nos. ML052590184, ML052920727, and ML052590187). The results of this survey ultimately formed the regulatory basis for the source terms used in the analysis to define the allowable isotopic concentration limits

in tables 1 and 2 of 10 CFR 61.55 that establish four classes of LLRW (Class A, Class B, Class C, and greater-than-Class-C). Table 1 provides limiting concentrations for long-lived radionuclides and table 2 provides limiting concentrations for short-lived radionuclides. As the LLRW class increases in hazard, greater controls (

e.g.,

protection for a longer period of time or greater burial depth) are required in order to reduce the risk from disposal of the LLRW. Class A LLRW is the least hazardous to the inadvertent intruder and requires the fewest controls, while Class C LLRW is more hazardous and requires additional controls. For example, Class C LLRW may require either greater burial depth or an engineered barrier that will prevent inadvertent intrusion for 500 years. The additional controls for Class C LLRW reduce the radiological risk from the greater hazard. Low-level radioactive waste with greater-than-Class-C concentrations of radionuclides is generally not suitable for near-surface disposal because of the radiological risk that can result from disposal of this LLRW without adequate barriers or other protective measures.

As part of the initial 10 CFR part 61 rulemaking, the NRC considered inadvertent intrusion scenarios and the physical stability and isotopic concentration of the LLRW when it developed the 10 CFR part 61 LLRW classification system. These isotopic concentration limits were based on the NRC's understanding of the characteristics and volumes of commercial LLRW reasonably expected for commercial disposal through the year 2000, as well as the potential disposal methods likely to be used.

In the Statement of Considerations for the final rule (47 FR 57457), the Commission noted the following:

[W]aste that is stable for a long period helps to ensure the long-term stability of the site, eliminating the need for active maintenance after the site is closed. This stability requirement helps to assure against water infiltration caused by failure of the disposal covers and, with the improved leaching properties implicit in a stable wasteform, minimizes the potential for radionuclide migration in groundwater. Stability also plays an important role in protecting an inadvertent intruder, since the stable wasteform is recognizable for a long period of time and minimizes any effects from dispersion of the waste upon intrusion.

The Commission also noted that “to the extent practicable, wasteforms or containers should be designed to maintain gross physical properties and identity over 300 years, approximately the time required for Class B waste to decay to innocuous levels . . . ” (47 FR 57457).

In addition to determining the acceptability of LLRW for disposal in a near-surface land disposal facility, the LLRW classification system is also integral to determining Federal and State responsibilities for LLRW and requirements for transfers of LLRW intended for disposal. The Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985) defines Federal and State responsibilities for the disposal of LLRW based on 10 CFR 61.55, as in effect on January 26, 1983. Specifically, the Act assigns responsibility for disposal of Class A, Class B, and Class C commercial LLRW to the States and responsibility for disposal of commercial LLRW with concentrations that exceed the limits for Class C LLRW to the Federal Government.

Appendix G to 10 CFR part 20, “Requirements for Transfers of Low-Level Radioactive Waste Intended for Disposal at Licensed Land Disposal Facilities and Manifests” (60 FR 15664; March 27, 1995), imposes manifest requirements on shipments of LLRW consigned for disposal. Manifests for LLRW shipments must identify the LLRW classification and a certification that the LLRW is “. . . properly classified, described, packaged, marked, and labeled. . . .”

C. Previous Public Interactions

On May 3, 2011, the NRC published preliminary proposed rule language (76 FR 24831) and an associated regulatory basis document, “Technical Analysis Supporting Definition of Period of Performance for Low-level Waste Disposal” (ADAMS Accession No. ML111030586) for public comment. The NRC staff conducted a public meeting on May 18, 2011, in Rockville, Maryland, to discuss the preliminary proposed rule language and its associated regulatory basis document. A summary and transcript of this meeting can be found in ADAMS under Accession No. ML111570329. The comment period ended on June 18, 2011, and the NRC received 15 comment letters from public interest groups, industry, and government organizations.

As a result of additional direction from the Commission in a SRM-COMWDM-11-0002/COMGEA-11-0002, “Revisions to Part 61,” dated January 19, 2012 (ADAMS Accession No. ML120190360), the NRC staff published, for public comment (77 FR 72997; December 7, 2012), a second version of the preliminary proposed rule language (ADAMS Accession No. ML12311A444) and an associated regulatory basis document, “Regulatory Basis for Proposed Revisions to Low-Level Waste Disposal Requirements (10 CFR part 61)” (ADAMS Accession No. ML12356A242). The comment period ended on January 7, 2013, and the NRC received an additional 24 comment letters from public interest groups, industry, and government organizations. Since these early comment periods were outside of the formal proposed rule notice-and-comment rulemaking process, the NRC staff did not and does not plan to prepare formal responses to the comments received on the preliminary documents. However, the NRC staff did consider these comments in the development of the proposed rule and some of the comments did result in modifications to the preliminary proposed rule language.

The NRC staff also briefed the Advisory Committee on Reactor Safeguards (ACRS), Radiation Protection and Nuclear Materials Subcommittee, on June 23 and August 17, 2011, and the full committee on July 13 and September 8, 2011. The NRC staff again briefed the ACRS, Radiation Protection and Nuclear Materials Subcommittee, on April 9, 2013, and the full committee on July 10, 2013. Summaries and transcripts of these meetings can be found at the ACRS' Web site,

http://www.nrc.gov/about-nrc/organization/acrsfuncdesc.html

.

Based on early comments and interactions with the ACRS, the NRC staff revised the preliminary proposed rule language.

III. Discussion

A. What action is the NRC taking?

The NRC is proposing to amend 10 CFR part 61 to require LLRW disposal licensees or license applicants to prepare a safety case that includes a defense-in-depth analysis and new and revised site-specific technical analyses to ensure that LLRW streams that are significantly different from the LLRW streams considered in the current 10 CFR part 61 regulatory basis can be disposed of safely and meet the performance objectives in subpart C of 10 CFR part 61. These new and revised analyses would also more easily identify any additional measures that would be prudent to implement for continued disposal of radioactive LLRW at a particular facility.

The NRC is also proposing to amend 10 CFR part 61 to require LLRW disposal facility licensees or license applicants to develop site-specific criteria for the acceptability of LLRW for disposal. These amendments maintain

the existing LLRW classification system, but permit disposal facility licensees or license applicants to account for facility design, disposal practices, and site characteristics to determine criteria for accepting future shipments of LLRW for disposal at their site. Because licensees or license applicants are required to develop site-specific criteria for the acceptability of LLRW for disposal, the NRC is also proposing to amend appendix G of 10 CFR part 20, “Standards for Protection Against Radiation,” to conform to the proposed requirements for LLRW acceptance. The NRC is also proposing additional amendments to the regulations to facilitate implementation and better align the requirements with current health and safety standards.

Table 1 compares the proposed new and revised technical analyses to the current 10 CFR part 61 requirements. The inadvertent intruder assessment would be a new requirement under 10 CFR 61.13 to demonstrate compliance with the performance objective to protect inadvertent intruders at 10 CFR 61.42. The inadvertent intruder assessment would have to demonstrate that the annual dose would not exceed a proposed 5 mSv (500 mrem) limit over a newly defined 1,000-year compliance period. A performance assessment would also be required for the protection of the general population from releases of radioactivity. This analysis would update the current exposure-pathway analysis to use a more modern performance-assessment methodology that would better align 10 CFR part 61 with the Commission's policy regarding the use of probabilistic risk assessment methods in nuclear regulatory analysis (60 FR 42622; August 16 1995). The performance assessment would also use a newly defined 1,000-year compliance period. The performance assessment would retain the current 0.25 mSv (25 mrem) annual dose limit and the as low as reasonably achievable (ALARA) concept, but the dose methodology would be consistent with the dose methodology specified in the standards for radiation protection set forth in the current 10 CFR part 20.

Given the significant uncertainties inherent in demonstrating compliance with the performance objectives over a long timeframe, a protective assurance period analysis would be required to demonstrate that the annual dose would be minimized below 5 mSv (500 mrem) or a level that is supported as reasonably achievable based on technological and economic considerations from the end of the compliance period through 10,000 years. Further, this analysis would need to consider new site features and processes occurring at the site that are different than what is considered during the compliance period.

Finally, a qualitative analysis covering a performance period of 10,000 years or more after site closure will also be required in 10 CFR 61.13 for those sites disposing of long-lived waste or if necessitated by site-specific conditions. This analysis would be required to assess how the disposal facility and site characteristics limit the potential long-term radiological impacts, consistent with available data and current scientific understanding, for the protection of the general population and the inadvertent intruder.

Defense-in-depth is an integral part of the safety case presented by the disposal applicant or licensee. Therefore, the defense-in-depth analyses are required in each one of the periods that are analyzed, as noted in Table 1.

Table 1—Comparison Table of Current and Proposed 10 CFR Part 61 Regulations

Protection of the general

population from releases of

radioactivity

(10 CFR 61.41)

Protection of individual from inadvertent intrusion

(10 CFR 61.42)

Stability of the disposal site after closure Long-term

analyses

(10 CFR 61.44)

Defense-in-depth

Current 10 CFR Part 61 regulations

—Pathway analysis

—Undefined period of performance

—0.25 mSv (25 mrem) annual whole body dose limit for the protection of the general population from releases of radioactivity

—ALARA concept.

—Comply with 10 CFR 61.55 LLRW classification and segregation requirements

—Provide adequate barriers to inadvertent intrusion

—Undefined period of performance

—No annual dose limit.

Analyses of active natural processes that demonstrate that there will not be a need for ongoing active maintenance of the disposal site following closure

Implicit in Subpart D technical requirements.

Proposed 10 CFR Part 61 regulations

Within 1,000 Years Following Closure of Disposal Facility (Compliance Period).

—Performance assessment that estimates peak annual dose that occurs within 1,000 years following closure of disposal facility

—0.25 mSv (25 mrem) annual dose limit for the protection of the general population from the releases of radioactivity that occurs within 1,000 years following closure of disposal facility

—ALARA concept.

—Comply with LLRW acceptance criteria

—Provide adequate barriers to inadvertent intrusion

—Intruder assessment that estimates peak annual dose that occurs within 1,000 years following closure of disposal facility

—5 mSv (500 mrem) annual dose limit

Analyses of active natural processes that demonstrate that long-term stability of the site can be ensured and that there will not be a need for ongoing active maintenance of the disposal site following closure

Analyses that demonstrate the proposed disposal system includes defense-in-depth protections.

Between 1,000 and 10,000 Years Following Closure of Disposal Facility (Protective Assurance Period).

—Performance assessment that estimates peak annual dose that occurs between 1,000 and 10,000 years following closure of disposal facility

—Annual dose shall be below 5 mSv (500 mrem) or a level that is reasonably achievable based on technological and economic considerations for the protection of the general population from releases of radioactivity that may occur between 1,000 and 10,000 years following closure of disposal facility

—Intruder assessment that estimates peak annual dose that occurs between 1,000 and 10,000 years following closure of disposal facility

—Annual dose shall be below 5 mSv (500 mrem) or a level that is reasonably achievable based on technological and economic considerations for the protection of the inadvertent intruders from exposures that may occur between 1,000 and 10,000 years following closure of disposal facility

—Analyses of active natural processes that demonstrate that long-term stability of the site can be ensured and that there will not be a need for ongoing active maintenance of the disposal site following closure

—Analyses that demonstrate the proposed disposal system includes defense-in-depth protections.

After 10,000 Years Following Closure of Disposal Facility (Performance Period).

—Analyses for 10,000 or more years following closure of disposal facility that demonstrates releases will be minimized to the extent reasonably achievable for the protection of the general population

—Analyses only apply for disposal sites containing long-lived radionuclides exceeding concentrations listed in table A of 10 CFR 61.13(e), or if necessitated by site-specific conditions

—Analyses that demonstrate how the facility has been designed to limit long-term releases

—Analyses for 10,000 or more years following closure of disposal facility that demonstrates exposures will be minimized to the extent reasonably achievable for the protection of inadvertent intruders

—Analyses only apply for disposal sites containing long-lived radionuclides exceeding concentrations listed in table A of 10 CFR 61.13(e), or if necessitated by site-specific conditions

—Analyses that demonstrate how the facility has been designed to limit long-term exposures to an inadvertent intruder

—Analyses that demonstrate the proposed disposal system includes defense-in-depth protections.

B. Who would this action affect?

This proposed rule would affect existing and future LLRW disposal facilities that are regulated by the NRC or an Agreement State.

C. Why do the regulatory requirements need to be revised?

Recently, the industry and the NRC have identified new LLRW streams that were not envisioned during the development of 10 CFR part 61. These LLRW streams include depleted uranium (DU) from enrichment facilities, LLRW from the U.S. Department of Energy (DOE) operations, and blended LLRW streams in quantities greater than previously expected. In addition, new technologies might result in the generation of different LLRW streams not previously evaluated during the development of the current 10 CFR part 61 regulations.

The renewed interest in licensing new uranium enrichment facilities in the United States has brought disposal of DU LLRW to the forefront of commercial LLRW disposal issues. In the regulatory basis supporting the development of current 10 CFR part 61, the NRC did not consider the relatively high concentrations and large quantities of DU LLRW that are generated by enrichment facilities. Additionally, the NRC did not anticipate that the DOE would dispose of large quantities of DU LLRW or any other defense-related LLRW in commercial disposal facilities. With the existing DOE DU stockpile at the Paducah and Portsmouth Gaseous Diffusion Plants, and the recent licensing of the Louisiana Energy Services National Enrichment Facility and the United States Enrichment Corporation American Centrifuge Plant, the DOE and the industry might need to dispose of more than 10

9

kilograms (1 million metric tons) of DU LLRW.

In a 2008 analysis provided in SECY-08-0147, “Response to Commission Order CLI-05-20 Regarding Depleted Uranium,” dated October 7, 2008 (ADAMS Accession No. ML081820762), involving a land disposal scenario for large quantities of DU, the NRC staff identified conditions that would likely not meet the current performance objectives in 10 CFR 61.41 and 10 CFR 61.42, if large quantities of DU were disposed under those conditions (

e.g.,

shallow disposal, such as that commonly associated with Class A LLRW, or disposal at humid sites with a potable ground water supply). The NRC staff determined that the disposal of large quantities of DU as Class A LLRW, with no additional restrictions, could result in inadvertent intruders receiving a dose greater than 5 mSv/yr (500 mrem/yr) for both acute and

chronic exposure scenarios. The estimated dose would result from pathways such as inadvertent ingestion of uranium-contaminated soil and inhalation of radon gas (a member of the uranium decay chain). These results are consistent with those found in an earlier analysis of possible DU disposal in an LLRW disposal facility discussed in a Sandia National Laboratories report titled, “Performance Assessment of the Proposed Disposal of Depleted Uranium as Class A Low-Level Waste” (ADAMS Accession No. ML101890179).

The blending of different classes of LLRW could also result in LLRW streams with concentrations that are inconsistent with the assumptions used to develop tables 1 and 2 of 10 CFR 61.55. Blending of LLRW would enable some materials that would otherwise have been disposed of as a higher class (

e.g.,

Class B or Class C LLRW) to be blended with a lower class (

e.g.,

Class A LLRW) or lower concentration LLRW of the same class. The result of the blending process would be to create large volumes of blended LLRW that have concentrations near the LLRW classification limits. The NRC did not evaluate the disposal of large volumes of LLRW with concentrations near the LLRW classification limits in the final regulatory basis for the current 10 CFR part 61. The LLRW concentration values published in the draft regulatory basis for the current 10 CFR part 61 were based on the assumption that all LLRW would be disposed at the LLRW classification limit. However, the final LLRW classification tables were developed with the assumption that only a fraction of the LLRW being disposed would approach the LLRW classification limit. In SECY-10-0043, “Blending of Low-Level Radioactive Waste,” dated April 7, 2010 (ADAMS Accession No. ML090410246), the NRC staff noted that large-scale blending of Class B and Class C concentrations of LLRW with Class A to produce a Class A mixture could result in a dose to an inadvertent intruder that is above 5 mSv/yr (500 mrem/yr) (

i.e.,

the dose limit used in developing the current LLRW classification in 10 CFR 61.55(a)).

Other unanticipated LLRW streams may also need to be considered for future disposal at LLRW disposal facilities. For example, the Energy Policy Act of 2005 expanded the NRC's regulatory authority under the Atomic Energy Act of 1954, as amended (AEA), to include discrete sources of naturally occurring radioactive material (including radium-226) that might be produced, extracted, or converted as a byproduct material. The regulatory basis for the current 10 CFR part 61 considered only a small quantity of radium-226 bearing LLRW in the development of the 10 CFR part 61 LLRW classification system.

1

More recently, consistent with the National Defense Authorization Act for Fiscal Year 2013,

2

LLRW also includes radioactive material that, notwithstanding Section 2 of the Nuclear Waste Policy Act of 1982, results from the production of medical isotopes that have been permanently removed from a reactor or subcritical assembly, for which there is no further use, and the disposal of which can meet the performance objectives in 10 CFR part 61. Because the types of LLRW streams requiring disposal at a LLRW disposal facility have expanded over time, the NRC has concluded that rulemaking is necessary to better ensure that a broad spectrum of LLRW types and volumes are disposed of in a manner that is protective of public health and safety and the surrounding environment.

1

For example, the equivalent of 0.5 nanocuries/gram of radium-226 contained in about 68 kg (about 150 pounds) of natural uranium ore (at equilibrium with its daughter products) was considered for the purposes of designating Class A LLRW (47 FR 57453-57454).

2

National Defense Authorization Act for Fiscal Year 2013. Subtitle F, Sec. 3173. Improving the reliability of Domestic Isotope Supply. H.R. 4310 (112th).

Further, as part of its regulatory effectiveness strategy described in NUREG-1614, Volume 6, “Strategic Plan Fiscal Years 2014-2018” (ADAMS Accession No. ML14246A439), the Commission strives, through its regulatory processes, to use risk-informed and performance-based approaches, where appropriate, to enhance the effectiveness and efficiency of the regulatory framework. The NRC concluded that amending the regulations to permit licensees or license applicants to develop criteria for LLRW acceptance from the results of the site-specific technical analyses as an alternative to the LLRW classification requirements allows for increased use of site-specific information to develop risk insights to support the safe disposal of LLRW. The new amendments also provide flexibility to determine how licensees can best meet the performance objectives for the specific design and operational practices of their disposal facility, as well as the specific environmental characteristics of their site.

Finally, the concept of “defense-in-depth” is currently not explicit in 10 CFR part 61. On February 11, 2011 (ADAMS Accession No. ML110680621), the NRC Chairman, Gregory B. Jaczko, created a Risk Management Task Force (RMTF), to develop a strategic vision and options for adopting a more comprehensive and holistic risk-informed, performance-based regulatory approach for reactors, materials, waste, fuel cycle, and transportation that would continue to ensure the safe and secure use of nuclear material. The RMTF issued NUREG-2150, “A Proposed Risk Management Regulatory Framework,” dated April 30, 2012 (ADAMS Accession No. ML12109A277). Three recommendations for LLRW were proposed in NUREG-2150. One of these recommendations was that the NRC should develop an explicit characterization of how defense-in-depth, within the proposed risk management framework, applies to the LLRW program and build this into current and future staff guidance documents and into training and development activities for the staff. This proposed rule would add a defense-in-depth requirement in 10 CFR part 61 to address the LLRW recommendations in NUREG-2150.

When would this rule become effective?

For the NRC licensees and license applicants, the rule would become effective 1 year after the final rule is published in the

Federal Register

. The Agreement States will have 3 years from the published date of the

Federal Register

notice for the final rule to adopt compatible regulations.

D. What LLRW streams are affected by this proposed rule?

The NRC considered a number of options in developing this proposed rule. The agency decided that requiring a safety case comprised of a collection of information that demonstrates the safety of a land disposal facility and includes site-specific technical analyses and defense-in-depth protections for all LLRW inventories would be the most comprehensive approach. This approach would ensure that as LLRW streams are generated, analyses would be performed to determine if the performance objectives would be met for disposal of all isotopic concentrations and volumes of LLRW. Under the proposed rule, all sites would be required to complete performance assessments and intruder assessments for the compliance period and the protective assurance period. In addition, land disposal sites with long-lived LLRW, or land disposal sites with site-specific conditions that would necessitate it, would be required to complete performance period analyses for the performance period.

E. What are site-specific technical analyses?

This rulemaking would require licensees and license applicants to prepare a performance assessment, a new intruder assessment, and new defense-in-depth analyses to demonstrate that its disposal site and design meet the performance objectives. Licensees and license applicants under 10 CFR part 61 would be required to prepare the following as part of their site-specific technical analyses: (a) A revised analysis, called a performance assessment, to demonstrate the protection of the general population from releases of radioactivity (10 CFR 61.41); (b) a new analysis, called an intruder assessment, to demonstrate the protection of inadvertent intruders (10 CFR 61.42); (c) performance period analyses to evaluate how the disposal system may mitigate the long-term risk from disposal of long-lived LLRW (10 CFR 61.13(e)); and (d) new analyses that demonstrate the disposal site includes defense-in-depth protections. The site-specific technical analyses would be required to be updated at facility closure, to provide assurance of compliance with the performance objectives for the disposal of LLRW streams that were not analyzed in the original 10 CFR part 61 regulatory basis.

1. Performance Assessment

The first performance objective of subpart C of 10 CFR part 61, which provides protection of the general population from releases of radioactivity, would continue to be demonstrated with a technical analysis that would be revised and renamed in 10 CFR 61.13 as a “performance assessment.”

3

A performance assessment, as described in NUREG-1636, “Regulatory Perspectives on Model Validation in High-Level Radioactive Waste Management Programs: A Joint NRC/SKI White Paper” (ADAMS Accession No. ML012260054), would be a systematic analysis that addresses what can happen, how likely it is to happen, what the resulting impacts are, and how these impacts compare to regulatory standards. The essential elements of a performance assessment for a LLRW disposal site are the same as the essential elements of a performance assessment for a HLW repository described in “Risk Assessment: A Survey of Characteristics, Applications, and Methods Used by Federal Agencies for Engineered Systems” (ADAMS Accession No. ML040090236). The essential elements of a performance assessment for a LLRW disposal site are: (a) A description of the site and engineered system, (b) an understanding of events likely to affect long-term facility performance, (c) a description of processes controlling the movement of radionuclides from LLRW disposal units to the general environment, (d) a computation of doses to members of the general population, and (e) an evaluation of uncertainties in the computational results.

3

The current 10 CFR part 61 refers to a “technical analysis.”

Many features, events, and processes can influence the ability of a LLRW disposal facility to limit releases of radioactivity to the environment. Disposal system behavior is influenced by the LLRW disposal facility design, the characteristics of the LLRW, and the geologic and environmental characteristics of the disposal site. A performance assessment evaluates the projected behavior of an LLRW disposal system and the uncertainties in the projected performance of the system. The performance assessment identifies the specific characteristics of the disposal site (

e.g.,

hydrology, meteorology, geochemistry, biology, geomorphology); degradation, deterioration, or alteration processes of the engineered barriers (including the wasteform and container) and natural system; and interactions between the disposal site characteristics and engineered barriers that might affect the performance of the LLRW disposal system. The performance assessment examines the effects of these processes and interactions on the ability of the LLRW disposal system to limit LLRW releases, and calculates the annual dose to a member of the public for comparison with the appropriate performance objective.

Currently, the descriptions of the technical information, technical analysis, and requirement to demonstrate compliance with the protection of the general population from releases of radioactivity can be found in 10 CFR 61.12, “Specific technical information,” 10 CFR 61.13(a), and 10 CFR 61.41, respectively, although these analyses are not called a “performance assessment.” In addition, these technical analyses do not have a prescribed compliance period. The original guidance documents associated with these requirements can be found in NUREG-1300, “Environmental Standard Review Plan for the Review of a License Application for a Low-Level Radioactive Waste Disposal Facility” (ADAMS Accession No. ML053010347); NUREG-1199, Revision 2, “Standard Format and Content of a License Application for a Low-Level Radioactive Waste Disposal Facility” (ADAMS Accession No. ML022550605); and NUREG-1200, Revision 3, “Standard Review Plan for the Review of a License Application for a Low-Level Radioactive Waste Disposal Facility” (ADAMS Accession No. ML061370484).

Proposed 10 CFR 61.41 would require licensees or license applicants to complete a performance assessment to estimate peak dose within the compliance period following closure of the disposal facility. The proposed compliance period is defined as 1,000 years following closure of the facility.

After the compliance period, licensees or license applicants would be required to provide analyses of the disposal facility performance from the end of the compliance period to 10,000 years. This period of time is referred to the protective assurance period. The analysis for the protective assurance period is an extension of the performance assessment to the timeframe following the compliance period. From a technical standpoint, the analysis for the protective assurance period is likely to be very similar to the compliance period performance assessment, but, given the uncertainty in projecting the performance of the disposal site over long time periods, uses a different metric (

i.e.,

minimize releases and keep annual doses below 5 mSv/yr (500 mrem/yr) or to a level that is supported as reasonably achievable based on technological and economic considerations). The metric for the protective assurance analyses is different from the dose limits provided for the compliance period. The protective assurance analyses are being proposed as a minimization process (

i.e.,

optimization) with guidance provided on the goals to use in the minimization process. The NRC is seeking feedback on the proposed approach.

The definition of compliance and protective assurance periods would add important technical parameters to the current technical analyses. Appropriate time periods are important for the evaluation of LLRW streams that were not considered in the original 10 CFR part 61 rulemaking as well as for evaluation of long-lived LLRW that were considered in the original rulemaking. The NRC believes that the results of a performance assessment would assist in demonstrating that the protection of the general population from releases of radioactivity can be achieved. The proposed 10 CFR 61.41, new definitions, technical analyses requirements, and concepts are risk-informed and flexible. Proposed 10 CFR 61.41 uses a risk-informed regulatory

framework that specifies what requirements need to be met and provides flexibility to a licensee or applicant with regard to what information or approach they use to satisfy those requirements. The NRC believes that the proposed approach is warranted because of the site-specific nature of LLRW disposal, which can rely on different designs operating at different sites.

The proposed amendments formally introduce the concept of features, events, and processes (FEPs), which ensure appropriate comprehensiveness of any site-specific technical analysis. For the protective assurance period, the performance assessment would need to reflect new FEPs different from the compliance period that address significant uncertainties inherent in the long timeframes only if scientific information compelling such changes is available. The NRC staff has developed a draft guidance document, NUREG-2175, “Guidance for Conducting Technical Analyses for 10 CFR part 61,” to facilitate the development of information and analyses that will support licensees or license applicants in addressing the regulatory requirements. This draft guidance document is being made available for public comment concurrent with this proposed rule. (See Docket ID NRC-2015-0003 in the Proposed Rules section of this issue of the

Federal Register

.)

2. Intruder Assessment

In 10 CFR part 61, the NRC recognizes that it is possible, though unlikely, that an inadvertent intruder might occupy a disposal site in the future and engage in normal pursuits without knowing that they are receiving radiation exposure. Therefore, the second performance objective in subpart C of 10 CFR part 61 is the protection of inadvertent intruders. Currently, 10 CFR part 61 does not require a site-specific analysis to demonstrate the protection of an inadvertent intruder. Instead, the safety of an inadvertent intruder is demonstrated by compliance with the LLRW classification system and the disposal requirements imposed for each class of LLRW. The connection between the LLRW classification system and protection of an inadvertent intruder is reflected in the LLRW classification tables in 10 CFR 61.55. The regulatory basis for the current 10 CFR part 61, published in NUREG-0945, contains an analysis of a reference disposal facility that evaluates the impacts of LLRW disposal on an inadvertent intruder. This analysis supported the concentration-based LLRW classification tables developed for 10 CFR 61.55.

Consistent with the development of the LLRW classification system, the technical analysis requirements currently found in 10 CFR 61.13(b) specify that the analyses of the protection of inadvertent intruders must include a demonstration that there is reasonable assurance that the LLRW classification and segregation requirements will be met and that adequate barriers to inadvertent intrusion will be provided. The regulations ensure the safety of the inadvertent intruder through the LLRW classification system and the LLRW disposal requirements imposed for each class of LLRW. However, as they are presently written, the regulations do not explicitly require an analysis of inadvertent intruder doses. Differences between LLRW disposal inventories, disposal practices, and the underlying assumptions used to develop the LLRW classification tables in 10 CFR 61.55 can result in varying doses with respect to the protection of an inadvertent intruder. Therefore, the new proposed regulatory provisions require licensees and license applicants to conduct an analysis of inadvertent intruder doses.

The proposed revisions would add a requirement for licensees and license applicants to conduct a site-specific intruder assessment to demonstrate compliance with 10 CFR 61.42. The proposed intruder assessment would quantitatively estimate the radiological exposure of an inadvertent intruder at an LLRW disposal facility following an assumed loss of institutional controls at the end of the active institutional control period. The results of the intruder assessment would then be compared to the performance objective in 10 CFR 61.42. The intruder assessment would identify the intruder barriers, examine the capability of the barriers, and address the effects of uncertainty on the performance of the barriers. The capabilities of the barriers to inhibit contact with the disposed LLRW or limit the radiological exposure of an inadvertent intruder and the time period over which the capability persists must be demonstrated and a technical basis must be provided. In performing the proposed intruder assessment, licensees would be expected to employ a methodology similar to that used for a performance assessment, but the intruder assessment would assume that an inadvertent intruder occupies the LLRW disposal site after closure, engages in normal activities, and is unknowingly exposed to radiation from the LLRW.

With the intruder assessment requirement, the NRC is proposing to specify an intruder dose limit for the compliance period and protective assurance period as described in the original 10 CFR part 61 analysis to develop the LLRW classification tables. The regulatory basis for 10 CFR part 61 assumed that inadvertent intrusion occurred following a cessation of a caretaker or active institutional control period. Institutional control of the site was expected to occur beyond the active institutional control period, although it could not be assured because of the long timeframes involved. Therefore, an intruder was assumed to occupy the LLRW disposal facility and engage in normal activities, such as agriculture or dwelling construction. The analysis assumed that the intruder directly contacted the disposed LLRW, and was exposed to radionuclides through inhalation of contaminated soil and air, direct radiation, and ingestion of contaminated food and water. The NRC based the LLRW classification tables in 10 CFR 61.55 on radionuclide concentrations that would yield a 5 mSv/yr (500 mrem/yr) dose.

The dose limit used to develop the current LLRW classification tables was selected from a range of values that were consistent with exposure guidelines of different orders of magnitude: 0.25 mSv/yr (25 mrem/yr), 5 mSv/yr (500 mrem/yr), and 50 mSv/yr (5,000 mrem/yr). In NUREG-0945, the NRC selected the 5 mSv/yr (500 mrem/yr) dose based primarily on safety as reflected in the effective dose limit in 10 CFR part 20 at that time and public opinion gained through the four regional workshops held on the preliminary draft of 10 CFR part 61. The NRC continues to believe that this dose limit provides an acceptable level of protection to an inadvertent intruder. The NRC is proposing to add an annual intruder dose limit to 10 CFR 61.42 to ensure protection of any inadvertent intruder who occupies the disposal site or contacts the LLRW at any time after active institutional controls are removed.

Given the uncertainty in projecting performance of disposal sites over long time periods such as those beyond the compliance period, the amendments proposed in 10 CFR 61.42 would require that annual doses be minimized, as estimated by an intruder assessment, for the protective assurance period. The minimization target is for annual doses to be below 5 mSv/yr (500 mrem/yr) or a level that is supported as reasonably achievable based on technological and economic considerations. The NRC is seeking feedback on the proposed

approach, especially with regard to whether a 5 milliSievert (500 mrem) annual dose target is appropriate for the protective assurance period and whether it is appropriate to require licensees or license applicants to consider alternative levels to minimize exposures to an inadvertent intruder.

Given the uncertainty in predicting human behavior into the distant future and to limit associated speculation, the NRC is proposing to change the definition of the inadvertent intruder to limit the scenarios to reasonably foreseeable activities that are realistic and consistent with activities in and around the disposal site at the time of closure.

As discussed in Section M of this document, the NRC has prepared a draft guidance document that describes acceptable approaches for determining reasonably foreseeable intruder activities that are consistent with activities in and around the disposal site at the time of closure to be assessed in the intruder assessment. The draft guidance describes how licensees or license applicants can take credit for physical characteristics (

e.g.,

water quality) and societal information (

e.g.,

land use patterns) related to the disposal facility to limit speculation about the types of activities in which an inadvertent intruder might engage.

The proposed approach, consistent with the current approach, is to assume that the active institutional controls will fail after the end of the active institutional control period. The NRC does not believe that controls will fail, but rather that the durability of the controls cannot be assured. In addition, the NRC is not assuming the probability is 100 percent that contact with the LLRW by an intruder will occur. As in the current regulation, engineered barriers and disposal practices, such as greater disposal depth, are to be considered in the intruder assessment. For example, with a protective cover of at least 5 m (16 feet) thickness, consideration of a scenario in which a dwelling foundation is excavated in a disposal unit would not be reasonable. A 5 mSv (500 mrem) dose limit for the intruder, compared to a 0.25 mSv (25 mrem) annual dose limit for the public during the compliance period in 10 CFR 61.41, demonstrates the NRC expectation that the intruder scenario is unlikely. As previously stated, the NRC is making available the draft guidance document (see Docket ID NRC-2015-0003) for public comment concurrent with the publication of this proposed rule and is seeking comments on whether the approaches described in the guidance are adequate or if further specification for inadvertent intruder scenarios in the proposed rule is necessary.

As previously indicated, the current 10 CFR part 61 provides LLRW classification and segregation requirements. The NRC considered, based on comments received on the preliminary proposed rule language (76 FR 24831), whether additional requirements such as minimum depth of disposal were needed for large quantities of long-lived LLRW (

e.g.,

DU). The NRC proposes that a more risk-informed approach would be to require an intruder assessment that would allow the actual disposal depth and form of LLRW to be considered in the analysis.

3. Performance Period Analyses

The current regulations in 10 CFR part 61 limit radiological risks from land disposal of LLRW regardless of the half-life of the LLRW. To ensure protection of public health and safety, 10 CFR part 61 includes regulations regarding analyses, LLRW classification, site-selection, LLRW characteristics, and other requirements. A long-term analysis (

e.g.,

longer than 10,000 years) was not necessary under 10 CFR part 61, as originally written, because the NRC developed LLRW classification limits for long-lived radionuclides. The regulatory system was designed to ensure the short- and long-term impacts were limited by regulatory requirements such as the LLRW classification system. The NRC is now proposing additional analyses to ensure that LLRW streams that are significantly different from those considered in the original 10 CFR part 61 regulatory basis (

e.g.,

large quantities of DU) can be disposed of safely and that the performance objectives will be met or LLRW disposal will be prohibited. The use of a three-tiered analyses system with different performance metrics for each tier should allow licensees or applicants to perform risk-informed assessments of the land disposal of LLRW for the protection of public health and safety. The analyses-based approach to regulation is more risk-informed than the concentration-based approach used in the current 10 CFR part 61 regulations. The concentration-based approach cannot be easily adjusted to differing site conditions because concentration limits were derived based on conservative assumptions.

The long-term analyses, termed “performance period analyses” as set forth in 10 CFR 61.13(e), would require licensees or license applicants to prepare long-term analyses (

i.e.,

after the compliance and protective assurance periods) that assess how the disposal facility and site characteristics limit the potential long-term radiological impacts, consistent with available data and current scientific understanding. The proposed performance period analyses will only be required for land disposal sites with long-lived LLRW that contains radionuclides with average concentrations exceeding the values listed in the proposed table A of 10 CFR 61.13(e), “Average Concentrations of Long-lived Radionuclides Requiring Performance Period Analyses,” or if necessitated by site-specific conditions. The average concentrations, as explained in greater detail in the associated draft guidance document, are disposal site-averaged concentrations. Disposal site-averaged concentrations can include the volume of the LLRW, uncontaminated materials used to stabilize LLRW or reduce void space within LLRW packages, the volume of uncontaminated materials placed within the disposal units, and the volume of engineered or natural materials used to construct the disposal units. For the purpose of determining if performance period analyses are necessary, the disposal site-averaged concentrations should be based on the total volume of LLRW averaged over the total volume of all disposal units. For radionuclides where the concentrations are based on mass and not volume, the average density of the different materials within the disposal units can be used. The averaging calculations are explained in further detail in the draft guidance document.

The metric for the performance period analyses would be to minimize releases to the public to the extent reasonably achievable. The NRC considered a variety of approaches for metrics to evaluate the performance period analyses. The aforementioned metric was selected because it would allow socioeconomic information to be considered in a risk-informed manner. Considering the timeframes involved, uncertainties may be considerable and therefore the precision typically assigned to a dose limit is not warranted. Whereas the calculated dose in a numerical model may be precise, the significance of that dose to a future generation is unknowable in the present. Although a dose limit is not prescribed, it is recommended that doses or concentrations and fluxes of radionuclides in the environment are calculated as they are appropriate to use to compare alternatives using a common metric. The NRC believes the value of information an applicant would provide to describe its actions to mitigate long-

term impacts to future generations is higher than the value of long-term dose estimates. The minimization of releases and barrier analyses for the performance period can demonstrate how an applicant is proposing to limit impacts to future generations. The draft guidance document discusses in more detail an acceptable approach to performing the analyses for the performance period.

The proposed performance period analyses must identify and describe the features of the design and site characteristics that will demonstrate that the performance objectives set forth in 10 CFR 61.41(c) and 10 CFR 61.42(c) will be met. These analyses would also help determine whether any additional measures are needed at a disposal site to ensure the protection of the general population and the inadvertent intruder from disposal of long-lived LLRW with average concentrations exceeding the values listed in the proposed table A of 10 CFR 61.13(e), or if necessitated by site-specific conditions, and to determine whether limitations on the disposal of some LLRW streams at certain sites may be needed to properly manage the disposal of LLRW.

An ending time for the performance period analyses is not specified in the proposed regulation. A number of factors influenced this decision. First, the analyses may demonstrate the time when the peak impact is likely to occur such that further calculation beyond this time is unnecessary. Because long-term impacts are going to be driven by site-specific characteristics and the particular LLRW that is disposed, the timing of peak impacts may differ substantially from site to site. A licensee or license applicant must demonstrate that impacts are minimized to the extent reasonably achievable, ensuring that facilities and disposal cells are not under-designed. Second, the analyses that are developed for the performance period may differ from traditional projections of long-term radiological doses. Performance period analyses may demonstrate that the performance period metrics have been satisfied irrespective of peak radiological impacts. The proposed approach is based on the position that there are many uncertainties in the risks imposed on future generations, especially from processes or events other than LLRW disposal. In addition, there is uncertainty in the projected radiological risk to future populations from LLRW disposal, which may be based on a number of assumptions about the behavior and characteristics of future society. The proposed approach focuses on a demonstration of how the natural and engineered barriers of the disposal system could limit releases of material rather than the radiological impact to an individual or group. The NRC is seeking feedback on the proposed approach, especially with regard to whether a dose limit is needed for the long-term analyses or whether the proposed metric combined with barrier analyses is more appropriate.

4. Defense-In-Depth Analyses

The defense-in-depth principle has served as a cornerstone of the NRC's deterministic regulatory framework for nuclear reactors, and it provides an important tool for making regulatory decisions, with regard to complex facilities, in the face of significant uncertainties. The NRC also has applied the concept of defense-in-depth elsewhere in its regulations to ensure safety of licensed facilities through requirements for multiple, independent layers, and, where possible, redundant safety systems. Traditionally, the reliance on independence and redundancy of barriers has been used to provide assurance of safety when reliable, quantitative assessments of barrier reliability are unavailable. The NRC maintains, as it has in other regulations for disposal, such as for high-level radioactive waste, that the application of the defense-in-depth concept to a LLRW land disposal facility is appropriate and reasonable. Therefore, the NRC is now proposing additional analyses to ensure that the land disposal facility includes defense-in-depth protections.

However, implementation of defense-in-depth protections, in the context of a LLRW land disposal facility, should be consistent with the NRC's goal of achieving a regulatory program and associated requirements that are risk-informed and performance-based. While waste is being disposed, and before a LLRW land disposal facility is closed, defense-in-depth protections would typically be comparable to other operating nuclear fuel cycle facilities licensed by the NRC. Application of defense-in-depth principles for regulation of disposal facility performance for long time periods following closure, however, must account for the difference between a closed land disposal facility and an operating facility with active safety systems and the potential for active control and intervention. A closed land disposal facility is essentially a passive system, and assessment of its safety over long timeframes is best evaluated through consideration of the relative likelihood of threats to its integrity and performance. Although it is relatively easy to identify multiple, independent and redundant layers that comprise the engineered features and site characteristics, the capabilities of any of these design features and site characteristics may not be either independent or totally redundant. The NRC continues to believe that multiple layers of defense must each make a definite contribution to the isolation of the waste, so that the NRC may find, with reasonable assurance, that no single layer of defense will be exclusively relied upon to achieve the overall safety objectives over timeframes of hundreds to thousands of years. Disposal of LLRW is also predicated on the expectation that a portion of the site in combination with engineered features will minimize the migration of radionuclides away from the disposal site. However, the capabilities of site characteristics and engineered features over the long timeframes are subject to interpretation and include many uncertainties. These uncertainties can be quantified generally and are addressed by requiring the use of a multiple layers. Similarly, although the composition and configuration of engineered features, as well as their capacity to limit releases or function as intruder barriers, may be defined with a degree of precision in the near-term that may not be possible for site characteristics, it is recognized that except for a few archaeologic analogues, there is no experience base for the performance of complex, engineered structures over periods longer than a few hundred years. Therefore, the NRC expects that licensees will rely on both the characteristics and the engineered features, in combination, to provide reasonable assurance that the overall performance of the disposal site will be adequate over long time periods.

5. Site Stability Analyses

Currently, 10 CFR 61.50, which is also being revised in this rulemaking, requires that LLRW disposal sites not be susceptible to erosion, flooding, seismicity, or other disruptive events or processes to such a degree or frequency that compliance with the 10 CFR part 61 performance objectives cannot be demonstrated with reasonable assurance. Currently, 10 CFR 61.44 also includes a performance objective for stability at the disposal site after closure. It states that the disposal facility must be sited, designed, used, operated, and closed to achieve long-term stability of the disposal site and to eliminate, to the extent practicable, the need for ongoing active maintenance of the disposal site following closure. To demonstrate with areasonable assurance

that the 10 CFR 61.44 performance objective will be met, licensees must conduct site stability analyses.

Site stability analyses focus on stability of the wasteform, stability of the engineered disposal facility, and geologic/geomorphic stability of the disposal site. For disposal of traditional LLRW (

i.e.,

range and type of LLRW that was analyzed in the current 10 CFR part 61), site stability analyses will likely focus on the former two areas. For disposal of large quantities of long-lived waste, the focus will likely be on the latter two areas. The extent of the site stability analyses will be strongly influenced by the type of waste to be disposed. Stability of wasteforms, disposal units, engineered barriers (such as cover systems), disposal site, disposal facility, and disposal system may all be within the scope of the stability assessment. However, the current 10 CFR 61.44 performance objective does not specify an analysis timeframe for the site stability analyses. Without an analysis timeframe, the applicability of the stability requirement would be subject to different interpretations.

The NRC proposes to revise 10 CFR 61.44 to specify that stability of the disposal site must be demonstrated for the compliance and protective assurance periods. This change was necessary to clarify that the post-closure site stability requirements apply to the compliance and protective assurance periods created in this proposed rule.

F. Updated Safety Case and Technical Analyses for Closure

Currently, 10 CFR 61.28, “Contents of application for closure,” requires licensees to submit an application to amend the license for closure. This application must include (1) a final revision and specific details of the disposal site closure plan, and (2) an environmental report or a supplement to an environmental report. Currently, 10 CFR 61.28 does not require licensees to prepare updated site-specific technical analyses. The proposed rule would require licensees to include updated safety case and technical analyses in their applications to amend their licenses for closure, to provide greater assurance of compliance with the performance objectives that ensure the safe disposal of LLRW streams significantly different from those considered in the original 10 CFR part 61 regulatory basis (

i.e.,

large quantities of depleted uranium). In particular, 10 CFR 61.28 would be revised to require licensees to also prepare updated performance period analyses required by proposed 10 CFR 61.13, 10 CFR 61.41, and 10 CFR 61.42. The NRC believes that this change, coupled with current 10 CFR 61.28(c) which is not being amended by this rulemaking, may require licensees to take additional action prior to closure to ensure that the LLRW that has been disposed of will meet the performance objectives.

G. What options were considered for selecting approach and timeframes and what is the NRC's preferred option?

1. Considerations Made in Developing Options

Currently, 10 CFR 61.7 discusses a number of timeframes that licensees or license applicants should consider in selecting a site, designing stable wasteforms or containers, controlling access to the site, and developing intruder barriers. The timeframes discussed are provided within the context of a LLRW management system that attempts to ensure that LLRW decays to innocuous levels prior to public exposure to radiation. The concentrations and quantities of long-lived LLRW for disposal would be limited thereby limiting potential exposures. For instance, 10 CFR 61.7(a)(2) indicates that in choosing a disposal site, site characteristics should be considered for the indefinite future and evaluated for at least a 500-year timeframe. However, 10 CFR part 61 does not provide a value for the time period

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to demonstrate compliance with the performance objectives. The existing regulatory basis for 10 CFR part 61 in NUREG-0945 and the related guidance in NUREG-1573, “A Performance Assessment Methodology for Low-Level Radioactive Waste Disposal Facilities: Recommendations of NRC's Performance Assessment Working Group” (ADAMS Accession No. ML003770778), recognize the need to use an analysis timeframe commensurate with the persistence of the hazard of the source. In selecting an analysis timeframe, the general practice is to consider the characteristics of the LLRW, the analysis framework (

e.g.,

assumed scenarios, receptors, and pathways), societal uncertainties, and uncertainty in predicting the behavior of natural systems over time. Both technical factors (

e.g.,

the characteristics and persistence of the radiological hazard attributed to the LLRW) and socioeconomic factors (

e.g.,

transgenerational equity) should be considered.

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The purpose of completing a performance assessment of a LLRW disposal facility is to ensure that public health and safety are protected with an acceptable degree of confidence.

4

Different terminology has historically been used to refer to the timeframe assessed for regulatory compliance or other analyses, including “performance period,” “time of compliance,” “compliance period,” and other variants.

5

International Commission on Radiological Protection (ICRP), “Radiation Protection Recommendations as Applied to the Disposal of Long-lived Solid Radioactive Waste,” ICRP Publication 81, Annals of the ICRP, Vol. 28, No. 4, ICRP Publication 81, 2000.

The NRC evaluated what other countries and international agencies use to manage the radiological risks from the disposal of long-lived LLRW. Some organizations impose a requirement to identify impacts from the disposal of long-lived LLRW using technical analyses. Results of the analyses are used to impose appropriate restrictions on LLRW disposal, if necessary. Almost every country that the NRC looked at places restrictions on how much LLRW can be disposed of in the near surface or does not allow near-surface disposal of long-lived LLRW. Most countries place explicit numerical limits on concentrations of long-lived alpha-emitting LLRW. These concentration limits are set by regulators based on generic technical analyses or policy decisions. The concentration limits are not developed based on the results of site-specific technical analyses. Site-specific technical analyses are performed, but only for LLRW that satisfies the generic limits. This approach is very similar to what was done for the initial development of 10 CFR part 61. The current requirements in 10 CFR part 61 supplement technical analyses with LLRW concentration limits and other disposal requirements, such as minimum disposal depth for certain types of LLRW. The development of concentrations limits by generic analysis or policy works well for countries that only have one disposal site. However, if numerous sites are regulated in this manner the concentration limits must be based on the most limiting conditions in order to assure that public health and safety is protected.

In general, different international programs have used regulatory approaches that vary considerably in methodology used to achieve protection of future generations from the disposal of LLRW. However, countries and international safety organizations consistently apply limiting conditions on the near-surface disposal of LLRW (

e.g.,

prohibit disposal, or impose concentration limits, disposal depth requirements, flux limits, and/or long-term analyses). Performance assessments are used to understand how a system (

e.g.,

a disposal facility and

natural environment) may perform. They are used to understand the potential impacts of uncertainties on public health and safety decisions that decision makers need to consider. The many sources of uncertainty associated with projecting the future risks from disposal of LLRW include, but are not limited to, natural, engineering, and societal sources. The selection of analyses timeframes or an approach to selection of analyses timeframes for the evaluation of the disposal of LLRW should consider the different sources of uncertainty and how the uncertainties may impact projected future radiological risk. The uncertainties influence how the projected future radiological risks are interpreted by decision makers. The staff evaluated these uncertainties and their impact on intergenerational decision making through review of the work by the National Academy of Public Administration, the Organization for Economic Co-Operation and Development, and others.

2. Options Considered

The NRC has considered a variety of options for selection of the analysis timeframe for the assessment of LLRW disposal.

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These options were based on two different approaches to waste management:

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The NRC developed a position paper on the analyses timeframe for LLRW disposal and a revised regulatory basis that provides more detail than the summary provided here. For more information, refer to the NRC's “Technical Analysis Supporting Definition of Period of Performance for Low-level Waste Disposal,” issued in April 2011, and “Regulatory Basis for Proposed Revisions to Low-Level Waste Disposal Requirements (10 CFR part 61),” issued in December 2012.

• Analyses-based approach to safety, and

• Design- and control-based approach to safety.

These two approaches are not mutually-exclusive and each can contain elements of the other approach. Traditionally, for the disposal of LLRW, analyses-based approaches projecting performance of the disposal facility into the future have been used. Disposal of municipal and industrial waste that is non-radioactive have used the design- and control-based approach to safety. The primary decision is what specific regulatory requirements are needed to ensure that public health and safety will be protected.

Analyses-based approach: A variety of different options were considered with respect to the analyses-based approaches. A key consideration of these approaches is the obligation of the current generation to protect future generations from the disposal of LLRW. Though this section discusses the NRC's options for analyses timeframes, the technical analyses should be considered in context with all the requirements of the regulation. The primary decision variables with respect to analyses timeframes considered by the NRC were:

• How many tiers should be used for the analyses?

• What should be the duration of the tiers?

• What limits should be prescribed to each tier?

Table 2 provides a summary of the analyses-based approaches considered by the NRC. A more in-depth discussion of the advantages and disadvantages of each approach can be found in the NRC's “Technical Analysis Supporting Definition of Period of Performance for Low-level Waste Disposal,” and “Regulatory Basis for Proposed Revisions to Low-Level Waste Disposal Requirements (10 CFR part 61)”.

Table 2—Summary of Timeframes Considered for Analyses-Based Approaches

Tiers

Approach

Duration

Limits

Single

Current—no change

Variable, from 500 years to peak dose as currently implemented by Agreement States

25 mrem/yr.

Single

Peak dose approach

Determined by specific waste and site characteristics

25 mrem/yr.

Single

Concentration limits

A few thousand

25 mrem/yr, Concentration limits.

Single

Limited duration

1,000 years or less

25 mrem/yr.

Two

Risk-informed analysis

Tier 1: up to 10,000 years

Tier 2: undefined

Tier 1: 25 mrem/yr.

Tier 2: minimize releases to the extent reasonably achievable.

Two

Risk-informed analysis with long-term dose limit

Tier 1: 10,000 years

Tier 2: undefined

Tier 1: 25 mrem/yr.

Tier 2: 100 mrem/yr.

Two

Site specific

Tier 1: a few hundred to 10,000 years

Tier 2: site-specific

Tier 1: 25 mrem/yr.

Tier 2: site-specific.

Three

Uncertainty limitation

Tier 1: 1,000 years

Tier 2: 10,000 years

Tier 3: undefined

Tier 1: 25 mrem/yr.

Tier 2: minimize releases using a target of keeping doses below 500 mrem/yr.

Tier 3: minimize releases to the extent reasonably achievable.

Three

Uncertainty informed

Durations not defined but examples are provided in “Technical Analysis Supporting Definition of Period of Performance for Low-level Waste Disposal”

Limits not defined but examples are provided in “Technical Analysis Supporting Definition of Period of Performance for Low-level Waste Disposal”.

Single Tier Options:

The regulatory requirements for a single-tier approach would involve specifying the timeframe of the analyses as well as an associated metric to be met during the timeframe. Variants of the single tier approach considered by the NRC included the following:

(a) Current—no change approach: In this approach, a compliance period is not specified for the assessment of the performance objectives. All four currently operating commercial low-level waste disposal facilities are located in Agreement States, and they all have different requirements for the compliance period. No additional action would be required by the NRC to maintain the current approach.

(b) Peak dose approach: This approach would require the calculation of peak dose for the compliance determination regardless of when the peak occurs (which could be greater than 10,000 years if large amounts of DU are disposed at the site). If regulatory limits are met, this approach ensures that all future generations would be provided with the same level of protection as the current generation. It would also ensure that the burden from the disposal of LLRW by the present generation is not deferred to any future generations, no matter how distant in the future.

(c) Regulator-derived concentration limits approach: This approach would involve using a single tier for the analyses of up to a few thousand years, complemented with regulator-derived concentration and quantity limits for long-lived isotopes. This approach is used by some other countries. The NRC believes this approach can be effective at mitigating the impact of long-term uncertainties while avoiding unnecessary speculation and ensuring protection of public health and safety for present and future generations. The challenge of using this approach is that it would be difficult to take into account different site, disposal facility, and other characteristics when determining regulator-derived concentration and quantity limits for long-lived isotopes. The NRC believes that this approach could work well for a single LLRW disposal site (which is most common in foreign nations), but would be difficult to implement in a risk-informed manner for numerous disposal sites. To ensure protection of public health and safety, the limits that would be derived using this approach may need to be set at values derived for the most limiting conditions (

e.g.,

site and design) and may be inappropriately restrictive for some sites.

(d) Limited duration approach: This approach would assign a 1,000-year compliance period to the analysis using a single tier. No limits would be prescribed for impacts that would occur after this period. Proposed guidance would indicate that it may be useful to evaluate longer-term impacts and consider modifications to the disposal system, if practical. A challenge with this approach is that, without limits on the disposal of long-lived isotopes, the dose estimated in a 1,000-year analysis timeframe may not be close in magnitude to the peak dose even for disposal of traditional LLRW. Another shortcoming of this approach is that a performance assessment could demonstrate that the performance objectives would be met within the first 1,000 years but then be exceeded by a large margin afterwards. In fact, this result would be expected, especially for the disposal of DU where the maximum dose achieved within 1,000 years is only about 1/1000th of the peak dose. Because Agreement States have selected different compliance periods, staff anticipates that the lack of a standard approach with respect to long-term impacts (after 1,000 years) will likely result in differences in interpretation among Agreement States. The approach would also create ambiguity with respect to the Commission's objectives for the management of long-term impacts. The decisions for additional action under this approach will be subjective, with case-by-case decisions being made by different regulators using different metrics.

Two Tier Options:

The regulatory requirements for a two-tier approach would involve specification of a duration for the analyses for each tier as well as an associated metric to be met for each tier. Variants of the two-tier approach considered by the NRC included the following:

(a) Risk-informed analyses approach: This approach sets standards for the analyses timeframes to ensure consistency, but then affords flexibility to licensees with respect to the technical analyses used to demonstrate compliance with the subpart C performance objectives. To ensure the long-term protection of public health and safety from the disposal of LLRW, the risk-informed analyses approach would be characterized by:

• A compliance period of up to 10,000 years.

• A second tier (

i.e.,

performance period) that would only be applicable when facility-averaged LLRW concentrations exceed certain values, or if necessitated by site-specific conditions. The concentrations would be developed by the NRC.

The analyses for the second tier would include: (1) A screening process to identify if performance period analyses are necessary, and (2) performance period analyses, if applicable. The performance requirement for the performance period analyses would be to minimize releases to the extent reasonably achievable. The analyses that could be used for the second tier would be described in guidance. The regulations would describe the analyses at a high-level.

Under this two-tiered approach, licensees or license applicants of LLRW disposal facilities that dispose of short-lived LLRW or limited quantities of long-lived LLRW would perform their compliance analyses, and no additional analyses would be required. If LLRW has average concentrations exceeding the values developed by the NRC, or if necessitated by site-specific conditions, then the licensees or license applicants would have to perform analyses for the second tier. Guidance would describe the use of a conservative screening analysis or, if desired, a site-specific technical analysis for the second tier. The screening analysis would be based on a conservative approach (

e.g.,

peak in-growth of progeny, no retardation during transport, defined scenarios) to manage long-term uncertainties and ensure that public health and safety is protected. If the screening analysis results showed the performance objectives would not be met, then inventory limits would be established based on the screening analysis or quantitative performance period analyses could be performed to demonstrate that public health and safety will be protected. Using this framework, the analyses would be risk-informed.

(b) Risk-informed analysis with long-term dose limits approach: This approach is conceptually similar to the previous two-tiered approach but differs in that a dose limit for the second tier (

i.e.,

post 10,000 years) of the analysis would be specified in the regulation (

e.g.,

1 mSv (100 mrem)) to align the requirement with regulatory precedent in similar programs (

e.g.,

high-level waste disposal at Yucca Mountain, LLRW disposal staff guidance).

(c) Site-specific approach: A final option using a two-tiered approach would be described as involving a compliance period of somewhere between a few hundred to 1,000 years, which would cover what the NRC believes is a reasonably foreseeable period for estimating future human activities. If uncertainty associated with the societal component of the problem is managed by specifying reasonably conservative scenarios, then the compliance period could be as long as 10,000 years. The time period for the second tier of this approach would not be defined in the regulation, instead it would be determined on a site-specific basis. Under this option a dose limit could be established for the second tier or an alternative metric could be used.

Three Tier Options:

a) Uncertainty limitation approach: This three-tiered approach involves a compliance period, a protective assurance period, and a performance period.

The

compliance period

would be defined as 1,000 years following closure of the disposal facility. The period of 1,000 years was selected to cover the

reasonably foreseeable future during which there would be a high degree of confidence that the requirements could be realistically met. Further, the compliance period would limit speculation on future human activities, as well as waste- and site-performance. The NRC would limit the impact of uncertainty on the compliance period decision making by limiting the duration of the compliance period.

The NRC recognizes that there is merit in considering timeframes longer than 1,000 years for some types of waste. Therefore, this approach would also establish a

protective assurance period

which would ensure that the disposal of LLRW would not present an unacceptable risk to future generations by minimizing radiation doses from the end of the compliance period until 10,000 years. The minimization process would be designed to ensure that radiological doses are maintained below 5 millisieverts (500 mrem) per year, or to a level that is reasonably achievable based on technological and economic considerations. The use of a protective assurance period with a minimization target rather than a dose limit would recognize the uncertainty in estimating future social patterns, living conditions, and environmental conditions in and around a disposal facility. The standard for the second tier is more similar to ALARA or optimization than a strict dose limit. The types of questions a licensee, license applicant, or regulator may consider when applying this approach would include but are not limited to:

• What are the projected doses?

• What other technologies are available to reduce those projected doses (

e.g.

different wasteforms, engineered covers)?

• If the doses are projected to be above 5 mSv/yr (500 mrem/yr), can they be reduced using technology in an economically justifiable manner?

• Could the waste stream be disposed at a different site? Is this site not suitable for this waste (

i.e.,

excess instability)?

The third tier of the approach is the

performance period.

The performance period would be used to evaluate the performance of the site after the protective assurance period and ensure that disposal system's ability to mitigate long-term risks associated with the disposal of long-lived LLRW is evaluated. The performance period would only apply if a facility is projected to contain sufficient long-lived radioactivity that could pose an unacceptable risk beyond 10,000 years.

(b) Uncertainty informed approach: This approach would provide decision points and regulatory limits that would consider major sources of uncertainty associated with the projection of radiological risk from the disposal of LLRW. This approach would be divided into three timeframes—compliance period, assessment period, and performance period—and is referred to as the Compliance, Assessment, and Performance approach (CAP).

The

compliance period

would be defined as the period of time when the disposal facility performance could be estimated quantitatively with relative confidence. Societal uncertainties, though large, would not prevent the performance calculations from providing meaningful information.

The

assessment period

would be the period of time after the compliance period where performance of the disposal facility would be assessed quantitatively and the results would be interpreted semi-quantitatively considering the increasing uncertainties in natural and engineered system components. The assessment period would be used to evaluate the relative performance of natural and engineered barriers.

The

performance period

would be the period of time after the assessment period where performance of the disposal facility would be evaluated qualitatively or quantitatively, as appropriate, because numerous and significant sources of uncertainty could significantly influence the results.

The objective of the CAP approach is to balance the need to consider radiological risks to future generations, even over long periods of time, with the uncertainties that could impact the interpretation of the results of the performance calculations. For LLRW inventories with long-lived radionuclides and with in-growth of more mobile progeny, the CAP approach is one way to ensure that the long-term risks would be incorporated into decision making. This three-tiered approach would ensure that the potential long-term radiological risks are communicated to decision makers while properly reflecting the uncertainties associated with the calculations. In the NRC's “Technical Analysis Supporting Definition of Period of Performance for Low-level Waste Disposal,” examples were given for defining the tiers and providing associated dose limits, however, specific values for each variable were not selected.

Design- and control-based approach: The NRC considered an approach to managing long-lived LLRW that requires periodic review and reassessment (

e.g.,

perpetual institutional control, monitoring, and maintenance), as is done with facilities that dispose of industrial metals. Currently, 10 CFR part 61 contemplates that involvement of a disposal site operator will follow a well-defined timeline. The more open-ended process associated with the disposal of industrial metals is viewed as a disadvantage to adoption of this type of approach.

Under current 10 CFR part 61, after satisfactory disposal site closure, licenses are transferred to the State or Federal Government, one of which is required to own the disposal site. A 5-year period during which the licensee would remain at the disposal site to ensure that the site is stable and ready for institutional control is required, though the Commission would be able to prescribe longer periods of time to demonstrate that the disposal site is stable, if warranted.

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The disposal site is transferred to the State or Federal Government after this period.

7

10 CFR 61.29.

3. NRC Proposed Option

The NRC proposed option is an approach to analyses timeframes that is based on a three-tiered conceptual framework. The proposed option includes a compliance period of 1,000 years applicable to both a performance assessment used to demonstrate compliance with 10 CFR 61.41 and to an intruder assessment used to demonstrate compliance with 10 CFR 61.42.

The second tier of the proposed option includes a 10,000 year protective assurance period, during which doses, as estimated by technical analyses, would be minimized. The objective of the minimization process would be to keep doses below 500 mrem/yr or to a level that is reasonably achievable based on technological and economic considerations. Should doses exceed the minimzation target, changes to the disposal site design, inventory limits, or alternative methods of disposal would be needed to ensure doses are minimized to avoid unacceptable consequences unless those changes can be shown to not be technically or economically practical. Given the significant uncertainties inherent in these long timeframes, the performance assessment should reflect changes in features, events, and processes of the natural environment such as climatology, geology, and geomorphology only if scientific information compelling such changes from the compliance period is available. The NRC is not proposing that features, events, and processes that are dynamic be arbitrarily fixed as static. Rather that

the scope of the features, events, and processes considered does not need to be expanded unless information is available to do so.

The third tier of the proposed option includes a performance period of undefined duration during which a licensee must demonstrate that effort has been made to minimize releases to the extent reasonably achievable. This metric for the third tier would afford the flexibility for consideration of long-term radiological doses, cost-benefit type of analyses, and concentration and fluxes of radionuclides in the environment. The duration is undefined to allow for consideration of site- and waste-specific factors as well as different methods to demonstrate that the requirements have been met. This approach was informed by the views expressed by various members of the public about the consideration of long-term uncertainties. Conditions have been established to determine when the performance period analyses should be performed, therefore risk-informing the approach. In order to determine if performance period analyses are necessary, it is proposed that a licensee or license applicant compare LLRW disposal site-averaged concentrations of long-lived radionuclides to values provided in the proposed table A of 10 CFR 61.13(e). This requirement would ensure that the analyses are performed only when dictated by the radiological characteristics of the LLRW or if necessitated by site-specific conditions. The concentration values are primarily, but not solely, based on the Class A LLRW concentration values from table 1 of 10 CFR 61.55. Unlike the existing table 1, the proposed table A includes non-transuranic long-lived isotopes, as well as transuranic long-lived isotopes. It is appropriate to include the non-transuranic isotopes in the performance period analyses if they could potentially be disposed of in significant concentrations and quantities. The radiological risk is estimated using the dose conversion factors of individual isotopes at the concentration provided (10 nanoCuries per gram (nCi/g)). The dose conversion factors for all isotopes have variability; there are different values of dose conversion factors for different solubility classes of an isotope as well as different values of dose conversion factors for different isotopes. When deriving the 10 nCi/g concentration value for transuranic isotopes in Class A LLRW, the NRC applied the same conversion of concentration to dose for all of these isotopes. The dose conversion factors for non-transuranic isotopes are generally comparable to the transuranic isotopes, and the NRC believes it is appropriate to simplify the variability similar to what was done in the original rulemaking. This simplification results in a single concentration value for all long-lived alpha emitting radionuclides rather than a table of values for different isotopes. The concentrations provided in the proposed table A of 10 CFR 61.13(e) are only used to determine if performance period analyses are necessary. As explained in detail in the draft guidance document, the complexity of the analyses would be driven by the projected impacts. The results of the performance period analyses would determine if any resultant actions are necessary (

e.g.,

establish inventory limits).

The specification of certain LLRW for which the performance period calculations apply to eliminates the need for all licensees or license applicants to develop performance period analyses. However, the language “or if necessitated by site-specific conditions” is needed because it is difficult to determine an absolute threshold for all sites below which the projected radiological risk, especially for 10 CFR 61.41, would be acceptably low. The risk to the public from the land disposal of LLRW can be driven by many variables, including but not limited to, concentration of LLRW, quantity of LLRW, disposal facility design, hydrogeology, release pathways, and receptor location and behavior. It is technically challenging to reduce this multi-dimension problem into one-dimension (

i.e.,

concentrations) in a risk-informed manner. The approach proposed in this rule attempts to address this issue by providing disposal site-averaged concentrations for which the long-term radiological risk is expected to be suitably low for most facilities, but would afford flexibility for additional analyses if warranted by site-specific conditions. The draft guidance document describes the types of conditions that may warrant performance period analyses even with the disposal of low concentrations of long-lived LLRW.

The reasons for selecting this option are:

• The tiered analysis that is required allows for tailoring of the analysis to the problem.

• The 1,000 year compliance period, appropriate for the disposal of short-lived LLRW, would ensure consistency among Agreement State regulators.

• By providing a 1,000-year compliance period, it would limit speculation and limit the impact of uncertainties on the compliance period decision making.

• By providing a protective assurance period, it would ensure that radiological impacts are minimized up to 10,000 years after closure. The miminization process would strive to maintain doses below 5 mSv/yr (500 mrem/yr) thereby providing protection to the public from the disposal of long-lived LLRW.

• By providing a goal rather than a limit for the second tier (

i.e.,

between 1,000 and 10,000 years), it would recognize the uncertainty about future society and environmental characteristics and allow consideration of economic and technological arguments to justify that doses are minimized to a level that is reasonably achievable. It may be economically and technically justifiable to reduce doses well below the target.

• Selective constraints are provided while affording regulatory flexibility, where warranted.

H. Why are the 1,000-year compliance period and 10,000-year protective assurance period appropriate?

The NRC's perspective is that impacts should be reliably calculated for the compliance period. The NRC is proposing to manage the increasing uncertainties associated with long timeframes by limiting the timeframe of the analyses and the scope of the analyses. Licensing decisions should be based on information that is reasonable, reliable, and knowable based on current understanding. The proposed approach limits the consideration of uncertainties associated with long timeframes.

One of the factors underlying the proposed approach was the DU LLRW stream. The DU radiological characteristics are somewhat unique in that DU is very long-lived and there is potentially a large quantity of DU that needs to be disposed. In addition, the hazard of DU increases over very long periods of time because of the slow decay of uranium and the in-growth of progeny. The time at which the concentration of radionuclides in the LLRW is within one order of magnitude of the peak concentration is sensitive to the assumed isotopic mass fractions in the initial LLRW. For depleted uranium this time is approximately 10,000 years or longer. The recommended approach is suitable for depleted uranium because though the impacts after 1,000 years would not be part of a compliance decision, they would be considered in the licensing process and a licensee must demonstrate that the impacts have been minimized after 1,000 years.

Performing analyses that ensure public health and safety are protected

when disposing of long-lived LLRW, and considering the information from the analyses in the decision-making process, is a risk-informed approach. However, it is not a risk-informed approach to disregard potential long-term impacts in the decision-making process because of large uncertainties without applying other regulatory requirements to ensure public health and safety will be protected. It would also not be a risk-informed approach to apply expensive and burdensome requirements on the present generation to offset hypothetical and unknown risks to generations long into the future. The proposed three-tiered approach balances these competing influences by having a 1,000-year compliance period, followed by site-specific technical analyses (minimization) for the period up to 10,000 years, and additional analyses beyond 10,000 years, when sufficient quantities and concentrations of long-lived LLRW would be disposed of. In the analyses performed in 2008 as part of the development of SECY-08-0147, the NRC staff estimated that concentrated, long-lived LLRW (

e.g.,

DU) could be disposed of in the near-surface but only in either limited quantities or under certain conditions. Without specifying regulatory requirements to either identify when the conditions for disposal are appropriate or to prevent disposal under inappropriate conditions, there may be instances when the performance objectives will not be met. Most other concentrated, long-lived LLRW in significant quantities may need some type of restrictions for near surface disposal. The proposed approach is to use site-specific technical analyses to identify what restrictions are necessary. Because waste disposal is a proposed future action, when all else fails or is too uncertain, inventory limits can be used to mitigate future risks.

I. Why is a 5 milliSievert per year (500 mrem per year) target appropriate for dose minimization during the protective assurance period?

Given the significant uncertainties inherent in demonstrating compliance with the performance objectives over a very long timeframe and to ensure a reasonable analysis, the analyses would be required to demonstrate that the annual dose should be minimized below 5 mSv (500 mrem) or a level that is supported as reasonably achievable based on technological and economic considerations from the end of the compliance period through 10,000 years. This 500 mrem/yr minimization target was chosen to limit releases to values that have been previously established by the NRC in 10 CFR part 20. For example, paragraph (e) in 10 CFR 20.1403, “Criteria for license termination under restricted conditions,” and paragraph (d) in 10 CFR 20.1301, “Dose limits for individual members of the public,” require annual dose limits of 5 milliSievert (500 mrem) in limited cases. This approach is designed to provide a target for minimization that takes into account the significant uncertainties over these long periods of time. As discussed in the guidance document, the minimization process most likely will result in projected impacts that are significantly lower then this mimization target. The NRC is seeking feedback on the proposed approach, especially with regard to whether a 5 milliSievert (500 mrem) annual dose goal is appropriate for the protective assurance period and whether it is appropriate to consider alternative, higher levels based on technological and economic considerations.

J. What are waste acceptance criteria (WAC)?

The NRC's current WAC can be found in subpart D of 10 CFR part 61, which specifies technical requirements for land disposal facilities for commercial LLRW. The technical requirements specify the classes and characteristics of LLRW that are acceptable for near-surface disposal, as well as other requirements. Currently, 10 CFR 61.55 provides the primary criteria related to LLRW acceptance and identifies the classes of LLRW acceptable for near-surface disposal (

i.e.,

the LLRW classification system). Section 61.56 identifies the minimum characteristics for all classes of LLRW and characteristics intended to provide stability of certain LLRW (

i.e.,

Class B and Class C LLRW). Additionally, 10 CFR 61.52(a) specifies requirements for near-surface LLRW disposal facility operation, including segregation and intruder barrier requirements for various classes of LLRW. Section 61.58 currently allows for other provisions for the classification and characteristics of LLRW on a case-by-case basis if, after evaluation, the Commission finds reasonable assurance of compliance with the performance objectives.

The LLRW classification system is well integrated with the requirements for LLRW characteristics and disposal facility operation. This integration stemmed from the generic nature of the original regulatory basis for 10 CFR part 61. The integrated requirements are intended to ensure that the performance objectives are met.

In addition to reviewing other regulatory approaches, the NRC also considered the original regulatory basis for 10 CFR part 61 in the development of the proposed revisions to 10 CFR 61.58. The principle basis used for setting the current 10 CFR part 61 classification limits, LLRW characteristic requirements, and operational requirements was limiting exposures to a potential inadvertent intruder at a reference LLRW disposal facility. Other considerations, such as long-term environmental impacts, LLRW disposal facility stability, institutional control costs, and financial impacts to small entities, were also considered. The NRC developed the LLRW classification system in 10 CFR part 61 from an analysis performed in 1981 of a representative LLRW disposal facility that was operated consistent with then-current practices and considered a projected set of LLRW streams (46 FR 38081; July 24, 1981). Specifically, the LLRW class limits were derived from an analysis that considered a combination of factors including radionuclide characteristics and concentrations, the wasteform, the methods of emplacement, and to some extent, the site characteristics. These factors influenced the concentration of radionuclides transferred from the disposed LLRW to the access points for the intruder scenarios. These factors are dependent upon the LLRW disposed, methods of emplacement, engineering design, and site characteristics, which can vary from facility to facility.

For example, one of the factors the NRC considered is site characteristics, which plays a role in the movement of radionuclides between environmental media (

e.g.,

soil to air). The movement of radionuclides depend on the environmental conditions at the location of the LLRW disposal facility. The reference LLRW disposal facility used in the original regulatory basis was not intended to represent any particular location, but rather, it was used to reflect the typical environmental conditions within its region. The NRC chose the southeastern region because, at the time, most of the LLRW was produced in the eastern portion of the nation and was projected to be disposed regionally. Today, only one of the four operating LLRW disposal sites is located in the eastern United States; the other three are located in the arid or semi-arid western United States. The Southeastern region was selected for the reference facility location because the environmental characteristics of the reference LLRW disposal facility were

expected to be conservative compared to more arid site locations.

Regardless of whether the assumptions regarding the LLRW, operational practices, facility design, or site characteristics of the reference LLRW disposal facility are consistent with current facilities, the NRC believes that the 10 CFR part 61 LLRW classification system remains protective of public health and safety for the LLRW streams that were analyzed in the development of the regulations because of the reasonably conservative nature of the analysis used to develop the LLRW classification system. However, inconsistency between actual site conditions and practices at an LLRW disposal facilities and the generic assumptions used to develop the LLRW classification system may cause the radionuclide concentration limits to be either overly restrictive or permissive. If radionuclide concentration limits are overly restrictive based on actual site characteristics, facility design, and operational practices, the LLRW classification system would ensure the safe disposal of LLRW, but it would impose unnecessary regulatory burdens on licensees and LLRW generators. Whereas, if the generic concentration limits at a LLRW disposal facility are overly permissive based on actual site characteristics, facility design, and operational practices, the LLRW classification system alone may not adequately ensure the protection of public health and safety. If the Commission found that the LLRW classification requirements were overly permissive at a particular disposal facility, it could impose additional requirements to ensure that the 10 CFR part 61 performance objectives would be met. Therefore, it's the 10 CFR part 61 performance objectives that ultimately ensure protection of public health and safety. However, the inconsistency between the generic assumptions and current practices highlights the need for flexibility to develop site-specific WAC. The site-specific WAC would provide assurance that public health and safety can be protected, while offering the possibility for the relief of unnecessary regulatory burdens for facilities with superior site characteristics, design, and operational practices. The specifics of WAC background information, other regulatory approaches regarding LLRW acceptance practices, technical considerations, and public comments are discussed further in Section 5.2, “Flexibility for Site-Specific Waste Acceptance Criteria,” of the regulatory basis document issued in December 2012.

In addition to considering the original regulatory basis for 10 CFR part 61, the NRC also performed a review of other regulatory approaches, domestic and international, regarding LLRW acceptance practices to develop the proposed revisions to 10 CFR 61.58. In general, practices vary but are constrained between specification of criteria by the regulatory agency and development of site-specific WAC by LLRW disposal facility operators. In all cases, the regulatory authority maintains oversight of disposal, including approval of the LLRW acceptance requirements.

1. Options Considered

The NRC considered three options for revising the regulatory framework associated with waste acceptance criteria for the near-surface disposal of LLRW. In the first option, the NRC considered maintaining the current approach for determining LLRW acceptability, namely the generic LLRW classification system. The NRC staff also considered a second option, in which the current LLRW classification system is replaced with criteria allowing flexibility for licensees or license applicants to determine site-specific WAC. Finally, the NRC considered a third option that would add flexibility to establish site-specific WAC to the existing LLRW classification system. These options are summarized as follows:

Option 1.

No change from current approach.

The regulations in 10 CFR part 61 currently provide general criteria for LLRW acceptability for near surface disposal through the classification and LLRW characteristics requirements set forth in 10 CFR 61.55 and 10 CFR 61.56. Because of the conservative nature of the assumptions used in the original 10 CFR part 61 regulatory basis to develop the LLRW classification, the LLRW classification system is expected to be protective of public health and safety as long as LLRW disposal facilities operate within the regulatory basis of the original 10 CFR part 61 regulations.

However, new practices that differ from the assumptions of the original analyses create uncertainty regarding the protectiveness of the LLRW classification system. For instance, new LLRW streams that were not considered during the development of 10 CFR part 61 are being considered for disposal (

e.g.,

large quantities of concentrated DU and LLRW resulting from the production of medical isotopes). Also, current LLRW disposal facility design and operational practices can differ from the generic assumptions employed in the development of the LLRW classification system (

e.g.,

disposal of LLRW containers in concrete vaults).

Currently, 10 CFR part 61 allows for alternative provisions for LLRW acceptability (

i.e.,

LLRW classification and characterization) on a case-by-case basis through 10 CFR 61.58. Section 61.58 allows the Commission, either upon request or upon its own initiative, to authorize alternate provisions for classification or characteristics of LLRW. The requirements for LLRW classification and characteristics are found in 10 CFR 61.55 and 10 CFR 61.56, respectively. Such alternative provisions could be authorized after an evaluation showing that the specific LLRW disposal facility, and disposal method being proposed, would provide reasonable assurance of compliance with the performance objectives. Agreement States that regulate LLRW facilities would apply their own regulatory provisions in these situations.

At present, only one of the four Agreement States that has an operating near-surface LLRW disposal facility has adopted a corresponding regulation to 10 CFR 61.58. Currently, Agreement States are not required to adopt 10 CFR 61.58, therefore, the Agreement State compatibility designation for 10 CFR 61.58 must be changed in order to require Agreement States to adopt an alternative provision for LLRW classification and characteristics. Agreement State compatibility designation for 10 CFR 61.58 is discussed further in Section VI, “Agreement State Compatibility,” of this notice.

Option 2.

Site-specific waste acceptance approach.

Another possible approach to provide flexibility for licensees or license applicants to determine site-specific WAC would be for the NRC to abandon the existing LLRW classification system and replace it with requirements for developing site-specific WAC from the results of the site-specific technical analyses. This approach would require LLRW disposal facilities to define the acceptability of LLRW. In defining LLRW streams with acceptable radionuclide concentrations or activities and wasteforms, LLRW disposal facilities would be required to use the results of the site-specific technical analyses set forth in the proposed 10 CFR 61.13. Under the site-specific LLRW acceptance approach, licensees and license applicants would also need to develop strategies for characterizing LLRW and methods to certify that LLRW meets acceptance criteria that are commensurate with the

analyses used to derive the site-specific WAC.

Removal of the current LLRW classification system from 10 CFR part 61 would present challenges because the LLRW classification requirements are well integrated with other requirements of 10 CFR part 61. For instance, license requirements for the operation of a LLRW disposal facility may reference the LLRW classes of 10 CFR 61.55. Therefore, complete replacement of the LLRW classification system would likely expand the effect of the rule revisions beyond the intended scope of this rulemaking.

Further, removal of the LLRW classification system from 10 CFR part 61 would not result in total abandonment of the system because the classification of LLRW is referenced in the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985). The Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985) establishes Federal and State responsibilities for the disposal of LLRW based on the LLRW classification system in 10 CFR part 61 as it existed on January 26, 1983. Specifically, Section 3 of the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985) states that the responsibilities of each State shall include the disposal of LLRW generated within the State (other than by the Federal Government) that consists of, or contains, Class A, Class B, or Class C LLRW, as defined by 10 CFR 61.55, in effect on January 26, 1983. Likewise, the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985) states that the Federal Government responsibilities shall include LLRW with concentrations of radionuclides that exceed the Class C limits established in 10 CFR 61.55 in effect on January 26, 1983.

Because the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985) relies on 10 CFR part 61 as it existed in 1983, removing the LLRW classification system from 10 CFR part 61 would not change the assignment of responsibilities for the disposal of commercial LLRW to the States and Federal Government. Therefore, the existing LLRW classification system would remain relevant to assigning responsibilities to the States and Federal Government, regardless of its presence in 10 CFR part 61.

Removal of the LLRW classification system from 10 CFR part 61, however, may create confusion among stakeholders about how responsibility is assigned. One possible approach to avoid confusion would be to maintain a version of the LLRW classification system in an appendix to 10 CFR part 61, for the sole purpose of aiding in the determination of Federal and State responsibilities for the disposal of LLRW. Alternatively, the LLRW classification requirements could be included in appendix G to 10 CFR part 20, where LLRW is manifested for shipment. The purpose of appendix G to 10 CFR part 20 is to address the various regulatory information needs for the transfer and disposal of LLRW. These informational needs, which were identified in the Statement of Consideration that accompanies the final rule (60 FR 15664) include, among others, access to information needed for assessments to demonstrate compliance with the performance objectives in 10 CFR part 61. This includes information necessary for the States and Compacts to carry out their responsibilities. Therefore, preserving the LLRW classification requirements in appendix G to 10 CFR part 20 would minimize confusion for shippers to provide accurate information that allows the States and Compacts to carry out their responsibilities.

The NRC is assuming that changes to the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985) will not be made to accommodate any revisions to the 10 CFR part 61 regulations. Instead, as previously noted, the NRC has developed a proposal that would implement this option without requiring changes to the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985).

Option 3.

Hybrid waste acceptance approach.

A third approach that the NRC considered would be to allow licensees or license applicants to develop site-specific WAC from the results of the technical analyses or from the requirements of the existing LLRW classification system. This proposed approach would still require licensees or license applicants to determine the acceptability of LLRW. In defining LLRW streams with acceptable radionuclide concentrations or activities and wasteforms, licensees or license applicants would be allowed to use either the results of the site-specific technical analyses set forth in 10 CFR 61.13, or the LLRW classification requirements in 10 CFR 61.55. Beyond the radionuclide limits and acceptable LLRW characteristics, licensees or license applicants would, as discussed previously in the site-specific waste acceptance approach, need to develop strategies for characterizing LLRW and methods to certify that LLRW meets acceptance criteria.

For licensees that choose to develop WAC based on the LLRW classification system in 10 CFR 61.55, this approach would not result in a significant additional burden to their current operating practices since they are currently using acceptance practices with essentially the same type of criteria. Licensees typically develop these site-specific WAC from the existing 10 CFR part 61 requirements and the NRC guidance.

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These licensees would still be required to demonstrate through the technical analyses set forth in 10 CFR 61.13 that they will meet the performance objectives. The required analyses may demonstrate that additional mitigation should be performed for certain LLRW streams, particularly those that were not considered in the development of the LLRW classification system.

8

NRC, “Branch Technical Position on Concentration Averaging and Encapsulation”, January 17, 1995, Division of Waste Management.

Because the hybrid waste acceptance approach would not alter the LLRW classification requirements in 10 CFR part 61, the approach also would maintain consistency between the LLRW classification requirements in 10 CFR part 61 and the assignment of Federal and State responsibilities in the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985), for the disposal of commercial LLRW. For instance, States may choose to permit the acceptance of LLRW designated as a Federal responsibility (

e.g.,

greater-than-Class-C LLRW) under the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985), if the results of the site-specific technical analyses demonstrate that greater-than-Class-C LLRW would be acceptable for disposal at a specific disposal facility. Further, under the existing 10 CFR part 61 regulations, though States are responsible for disposal of LLRW with concentrations less than the upper limits for Class C, some States have exercised flexibility to further limit disposal of certain LLRW for which they are responsible at specific LLRW disposal facilities. The NRC proposes not to alter this flexibility under this proposed approach. In all cases, the regulatory authority maintains oversight of disposal, including approval of the LLRW acceptance requirements.

The NRC also considered whether licensees and license applicants should have the flexibility to consider alternative active institutional control periods to derive site-specific WAC, under both the site-specific waste acceptance and hybrid waste acceptance approaches. To allow this flexibility when developing site-specific WAC, the NRC would need to revise 10 CFR 61.59 to permit licensees or license applicants

to develop site-specific WAC for periods beyond 100 years.

During the original development of 10 CFR part 61, in NUREG-0782, “Draft Environmental Impact Statement (EIS) on 10 CFR part 61 `Licensing Requirements for Land Disposal of Radioactive Waste' ” (ADAMS Accession No. ML052590348), the NRC considered a range of time periods for active institutional controls but decided that 100 years is an appropriate period for determining how long the government would be able to ensure custodial care for a near-surface disposal facility. When the public commented that longer times would be appropriate, the NRC determined that, while the longevity of government may reasonably be assumed to extend beyond 100 years, the limit is tied to the possibility of bureaucratic error, which is more difficult to assess. For example, the government could, at some future date, unintentionally permit activities on the site as a result of an incomplete records search. The NRC indicated that it saw no compelling reason to abandon a 100-year institutional control period. Further, the institutional control period is a regulatory component of defense-in-depth by limiting the period of time over which oversight would need to be effective. Federal regulations for disposal of a variety of waste, including municipal and hazardous wastes, allow for a wide range of institutional control periods. International approaches for LLRW disposal vary for the period over which institutional controls are assumed to function, but generally they are limited to 300 years or less. Therefore, allowing unlimited flexibility would appear to be inconsistent with current international practice regarding the longevity of institutional controls.

Since the 100-year time duration is an integral assumption in the analyses that originally derived the radionuclide concentration limits set forth in 10 CFR 61.55, the hybrid waste acceptance approach would also need to maintain the current 100-year limit for licensees or license applicants that continue to use the LLRW classification system. The NRC maintains its earlier assessment and sees no new compelling reason to consider a revision to 10 CFR 61.59. Therefore, the NRC proposes to maintain the 100-year limit set out in 10 CFR 61.59.

2. NRC Proposed Option

In the proposed rule, the NRC is proposing the hybrid waste acceptance approach (Option 3) as the regulatory LLRW acceptance framework for the near-surface disposal of LLRW. The hybrid waste acceptance approach provides a framework for the use of either the generic LLRW classification system specified in 10 CFR 61.55 or the results of the technical analyses required in 10 CFR 61.13. Either approach, when combined with the other revisions recommended for this rulemaking, would provide reasonable assurance that public health and safety would be protected. The hybrid waste acceptance approach would provide a framework for determining LLRW acceptability at a disposal facility while achieving the following:

• Providing flexibility to develop site-specific WAC;

• minimizing revisions to 10 CFR part 61;

• maintaining consistency with the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985);

• limiting additional regulatory burden on licensees and license applicants;

• providing States flexibility to exercise their regulatory authority within a national framework; and

• maintaining consistency with the range of domestic and international practices for the disposal of LLRW.

The implementation of the hybrid waste acceptance approach would require revisions to 10 CFR part 61 that allow land disposal facilities flexibility to establish site-specific WAC based either on the LLRW classification system specified in 10 CFR 61.55 or the results of the analyses required in 10 CFR 61.13 for any land disposal facility. The use of the LLRW classification system would be limited to a near surface disposal facility because the LLRW classification requirements were originally developed as technical requirements for disposal in a near-surface LLRW disposal facility. The revisions would specify the minimum content of the WAC and the proposed 10 CFR 61.52(a)(12) would limit the disposal facility to disposing only LLRW that meet the WAC.

The revisions would also require licensees or license applicants to develop approaches and methods for generators to characterize LLRW, to certify that LLRW meets acceptance criteria in order to demonstrate compliance with the WAC, and to annually review the content and implementation of the LLRW acceptance program. Requiring licensees and license applicants to specify acceptable methods to characterize LLRW, ensures that generators appropriately characterize the LLRW and that the data are sufficient to demonstrate that the disposal facility's WAC are met. Certification requirements ensure an appropriate administrative process developed by the licensees or license applicants is used by generators to demonstrate that the WAC are met, that necessary records are maintained, and that certified LLRW is managed to maintain its certification. Resource burdens associated with administrative and recordkeeping processes used to demonstrate compliance with disposal facility's WAC requirements are further discussed in Section X, “Paperwork Reduction Act Statement,” of this document and the accompanying draft regulatory analysis.

Additionally, implementation of the hybrid waste acceptance approach requires revisions to specific manifesting requirements specified in sections I, II, and III of appendix G to 10 CFR part 20 and the related guidance in NUREG/BR-0204, “Instructions for Completing NRC's Uniform Low-Level Radioactive Waste Manifest” (ADAMS Accession No. ML071870172), that provide information considered important for demonstrating compliance with the performance objectives and for States and Compacts to carry out their responsibilities under the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985). The proposed revisions to appendix G to 10 CFR part 20 ensure that specific manifesting requirements, which were previously linked directly to the LLRW classification requirements, are revised to maintain consistency with the proposed requirements for LLRW acceptance in 10 CFR part 61. The proposed revisions to appendix G to 10 CFR part 20 also ensure that information important for States and Compacts to carry out their responsibilities under the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985) will continue to be reported.

K. What other changes are proposed?

The NRC is proposing additional changes to the 10 CFR part 61 regulations to facilitate implementation and better align the requirements with current health and safety standards. These changes would include: (1) Adding new definitions to 10 CFR 61.2, “Definitions,” and updating concepts in 10 CFR 61.7; (2) implementing changes to appendix G to 10 CFR part 20, to conform to proposed LLRW acceptance requirements; (3) modifying site suitability requirements in 10 CFR 61.50, to be consistent with the proposed analyses framework; and (4) Updating the dose calculation system used in 10 CFR part 61.

1. Adding New Definitions to 10 CFR 61.2 and Updating Concepts in 10 CFR 61.7

Currently, 10 CFR 61.2 defines common terms used in 10 CFR part 61 and 10 CFR 61.7 provides conceptual information for the disposal facility LLRW classification and near-surface disposal, and licensing process for LLRW disposal facilities. These concepts include descriptions of: (a) The parameters for near-surface disposal in engineered facilities and the layout of land and buildings necessary to carry out the disposal; (b) the safety objectives for near-surface LLRW disposal, which emphasize the stability of the wasteforms and disposal sites; and (c) the licensing processes that the licensees or license applicants go through during the preoperational, operational, and site closure periods.

The NRC proposes to add definitions and concepts to 10 CFR 61.2 and 10 CFR 61.7, respectively, to support the site-specific technical analyses and LLRW acceptance requirements. These terms and concepts are needed to provide consistency and facilitate implementation of the proposed 10 CFR part 61 regulations.

The NRC is proposing to add definitions for “compliance period,” “defense-in-depth,” “intruder assessment,” “long-lived waste,” “performance assessment,” “performance period,” “protective assurance period,” and “safety case” to facilitate implementation of the proposed requirements for site-specific analyses. The definitions for the various analyses and time periods are necessary to support the requirements for the performance objectives and technical analyses. Three specific definitions deserve to be discussed in greater detail are “long-lived waste” because the proposed performance period analyses are only necessary for the disposal of long-lived LLRW, “defense-in-depth” because licensees will be required to demonstrate how the disposal facility relies upon multiple independent and redundant layers, and “safety case” because the requirements are central to demonstrating that public health and safety will be adequately protected at present and in the foreseeable future.

The performance period analyses are designed to be completed if a facility will be disposing of long-lived LLRW. The proposed “long-lived waste” definition contains three components. The first component is a radionuclide that does not decay sufficiently over the compliance period. The reason the NRC is expressing this as a percentage of initial activity of a radionuclide that remains after 10,000 years, instead of a half-life value such as 3,000 years as suggested by some members of the public, is to ensure that stakeholders understand that the “long-lived waste” definition is conditional on the analyses framework. If the analysis framework were to be changed in the future or if a different framework was used, for instance, in a different country, a half-life of 3,000 years may or may not be appropriate. The second component is a long-lived radionuclide parent that produces short-lived radionuclide progeny. The second component is designed to ensure that the analysis includes radionuclide progeny, such as those resulting from the uranium decay series. The third component is a short-lived radionuclide parent that results in long-lived radionuclide progeny. Examples would include the curium decay series or the isotope Am-241 which produces Np-237, a long-lived radionuclide that can be fairly mobile in the environment. The inventory of LLRW at the time of disposal can differ considerably from the inventory at future times. The “long-lived waste” definition is designed to take this into account.

The concept of defense-in-depth has been implicitly used in LLRW regulations in the past, but it has not previously been explicitly defined in 10 CFR part 61. Defense-in-depth is implicitly provided through the various regulatory requirements. For instance, while 10 CFR 61.59 imposes land ownership and institutional control requirements that are intended to limit the potential for intrusion into a closed disposal facility, licensees may not take credit for these protections beyond 100 years when assessing whether the performance objectives will be met. The NRC's defense-in-depth approach to risk management ensures that safety is not wholly dependent on any single element of the design, construction, maintenance or operation of a regulated facility. With the potential disposal of DU and other long-lived LLRW in shallow land disposal facilities, defense-in-depth takes on additional importance and it is now being defined and explicitly used in this proposed revision to 10 CFR part 61 to provide assurance that safe disposal can be achieved in light of the significant uncertainties associated with projecting doses far into the future. Defense-in-depth for a land disposal facility includes, but is not limited to, the use of remote siting, consideration of waste forms and radionuclide content, engineered features, and natural geologic features of the disposal site.

Regarding the proposed definition for “safety case,” licensing decisions are based on whether there is reasonable assurance that the performance objectives can be met. The technical analyses are used to demonstrate that the performance objectives can be met. These analyses together with defense-in-depth protections and the supporting evidence and reasoning for the strength and reliability of these analyses and protections form the “safety case” for licensing a LLRW facility. The safety case must make a convincing conclusion that public health and safety will be adequately protected from the disposal of LLRW (including long-lived LLRW). A clear case for the safety of a disposal facility would also enhance communication among stakeholders.

2. Implementing Changes to Appendix G to 10 CFR Part 20 to Conform to Proposed LLRW Acceptance Requirements

Appendix G to 10 CFR part 20 imposes manifest requirements on shipments of LLRW consigned for disposal. The purpose of the requirements in appendix G to 10 CFR part 20 is to address various regulatory information needs for the transfer of LLRW. These information needs, which were identified in the Statement of Consideration accompanying the current regulations (60 FR 15664), include access to information needed for the analyses to demonstrate compliance with the performance objectives and that the States and Compacts believe is necessary to carry out their responsibilities. In particular, manifests for LLRW shipments must identify the LLRW classification and certify that the LLRW is “. . . properly classified, described, packaged, marked, and labeled . . . .” Therefore, the NRC is proposing changes to these requirements to conform to the proposed addition of the LLRW acceptance requirements in 10 CFR 61.58.

To meet these needs, the requirements in appendix G to 10 CFR part 20 require shippers to properly classify, describe, package, mark, and label LLRW that will be transferred and is intended for disposal. Further, shippers must certify that these actions have been completed in accordance with the applicable requirements, including those in 10 CFR part 61 for LLRW classification (

i.e.,

10 CFR 61.55), characteristics (

i.e.,

10 CFR 61.56), and labeling (

i.e.,

10 CFR 61.57). Therefore, the NRC is also proposing to amend the regulations at appendix G to 10 CFR part 20 to conform to the flexibility afforded by the proposal to determine site-specific WAC.

Specifically, sections I.C.12 and I.D.4 of appendix G to 10 CFR part 20 currently require the shipper of LLRW consigned to a LLRW disposal facility to identify the LLRW classification per 10 CFR 61.55 and to state if it meets the structural stability requirements of 10 CFR 61.56(b) on the uniform manifest. Because the proposed revisions to 10 CFR 61.58 allow a licensee or license applicant to use the classification system to develop site-specific WAC, shipping manifest requirements related to LLRW classification will be retained so that States and Compacts continue to receive information allowing them to carry out their responsibilities as defined by the Low-Level Radioactive Waste Policy Act of 1980 (as amended in 1985).

Information on LLRW acceptability at a disposal facility is essential to demonstrate compliance with the performance objectives. Therefore, the NRC proposes adding a requirement to section II of appendix G to 10 CFR part 20 to specify in the uniform manifest whether the LLRW being shipped to a disposal facility conforms to the facility's WAC. The addition of this requirement would also require a revision of NRC Form 541, “Uniform Low-Level Radioactive Waste Manifest-Container and Waste Description,” to conform to this new requirement and the accompanying guidance NUREG/BR-0204, Revision 2.

Further, the proposed requirements for LLRW acceptance would require revisions to the certification requirements of section II of appendix G to 10 CFR part 20. Section II requires LLRW generators, processors, or collectors to certify that the transported LLRW is properly classified. Since the proposed 10 CFR part 61 requirements would require licensees and license applicants to develop criteria for LLRW acceptability using either the existing LLRW classification system or the results of site-specific analyses, this certification requirement would be updated so that shippers are certifying that LLRW consigned to a disposal facility meets the facility's waste acceptance criteria for LLRW acceptability.

The proposed 10 CFR part 61 requirements for LLRW acceptability would also require revisions to section III of appendix G to 10 CFR part 20. Section III of appendix G to 10 CFR part 20 imposes requirements on the control and tracking of LLRW transferred to a disposal facility. Specifically, current sections III.A.1 through 3 and III.C.3 through 5 require the LLRW to be classified according to 10 CFR 61.55 and meet the LLRW characteristics requirements in 10 CFR 61.56. The container must be labeled with the appropriate LLRW class, and the licensee who transfers the LLRW must implement a quality assurance program to assure compliance with 10 CFR 61.55 and 10 CFR 61.56. Since the proposed 10 CFR part 61 requirements would require licensees or license applicants to develop criteria for LLRW acceptability using either the existing LLRW classification system or the results of site-specific technical analyses, these requirements would be revised so that shippers are preparing, labeling, and providing quality assurance in accordance with the disposal facility operator's criteria for LLRW acceptability.

3. Modifying the Site Suitability Requirements in 10 CFR 61.50 To Be Consistent With the Proposed Analyses Framework

The site suitability requirements in 10 CFR 61.50 specify the minimum characteristics a disposal site must possess to be acceptable for use as a near-surface disposal facility. The primary factors considered for disposal site suitability are isolation of LLRW—which is dependent on the radiological characteristics of the LLRW—and disposal site features that ensure that the long-term performance objectives of subpart C of this part are met, as opposed to short-term convenience or benefits. The concept of site characteristics is explained in 10 CFR 61.7. Site characteristics should be considered in terms of the indefinite future, take into account the radiological characteristics of the LLRW, and be evaluated for at least a 500-year timeframe. Site characteristics and site suitability requirements play an integral role in ensuring that the site is appropriate for the type of LLRW proposed for disposal. When the site suitability requirements were originally developed, it was envisioned that LLRW would primarily contain short-lived radionuclides with low concentrations of long-lived radionuclides. The NRC developed the LLRW classification framework around this concept. However, the regulation at 10 CFR 61.55(a)(6) allows long-lived LLRW not currently listed in table 1 or 2 of 10 CFR 61.55 to be disposed in the near surface as Class A LLRW.

In the proposed revision, it is recognized that not all LLRW may decay to relatively innocuous levels within 500 years and so a technical analysis would be required to determine if site-specific restriction of disposal of LLRW is necessary. The regulation at 10 CFR 61.50 would be revised to clarify the interpretation of site characteristics. The site suitability characteristics have not been changed, but have been reorganized to distinguish the hydrological site characteristics from other characteristics. The hydrological site characteristics have been separated to clarify that for 500 years the hydrological site characteristics must be met regardless of the results of any technical analyses. Historically, most of the problems encountered in LLRW disposal resulted from water impacting the LLRW disposal system. A site that is unlikely to satisfy the hydrological site characteristics (

e.g.,

disposal of LLRW in the zone of water table fluctuation, flooding) in the next 500 years is unlikely to be defensibly characterized and modeled. If the site cannot be defensibly characterized and modeled, the radiological risk from the disposal of LLRW cannot be reliably projected. The short-lived radionuclides that are disposed of can result in significant impacts if they are improperly managed. Therefore, the hydrological site characteristics are treated differently than the other site characteristics. After 500 years for hydrological characteristics and for all timeframes for other characteristics, it is appropriate to consider if the characteristics will limit the ability of the licensee or applicant to meet the 10 CFR part 61 subpart C performance objectives. Historically, the other characteristics have not been associated to a significant degree with problems encountered in LLRW disposal. Therefore it is anticipated that it is less likely that the other characteristics will be associated with performance issues compared to the hydrological characteristics. The proposed revisions to 10 CFR 61.50 clarify the requirements for site suitability. Stability is a cornerstone of waste disposal. Future instability of a waste disposal site may provide the basis to limit or prohibit disposal of certain types of waste if the stability of the disposal site cannot be ensured. Future instability of a disposal facility may prohibit accurate characterization and performance assessment modeling.

4. Updating the Dose Calculation System Used in 10 CFR Part 61

Currently, 10 CFR 61.41 requires that concentrations of radioactive material released to the general environment “not result in an annual dose exceeding an equivalent of 0.25 mSv (25 mrem) to the whole body, 0.75 mSv (75 mrem) to the thyroid, and 0.25 mSv (25 mrem) to any other organ of any member of the public.” The objective of modeling in a performance assessment that would be

used to evaluate compliance with 10 CFR 61.41 is described in NUREG-1573, and provides estimates of doses to humans from radioactive releases from an LLRW disposal facility after it has been closed.

Currently, 10 CFR part 20 provides for the use of current NRC health physics practices for NRC licensees. In May 1991, the NRC updated 10 CFR part 20 based on a dosimetric modeling and effective dose equivalent approach described in the International Commission on Radiological Protection (ICRP) Publications 26 and 30.

9

In 1991, the 10 CFR part 20 standards were updated to the total effective dose equivalent (TEDE) approach, consistent with the Federal radiation protection guidance signed by the President on January 20, 1987 (56 FR 23360), for occupational exposure to implement the ICRP recommendations found in Publication 26. The current 10 CFR part 61 dose limits, and several others within the regulations, stem from a method of calculating and limiting doses that date back to the late 1950s and were based on recommendations in ICRP Publication 2.

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The NRC proposes to revise the 10 CFR part 61 regulations to require licensee to use the dose calculation methodology found in ICRP Publication 26 and allow the use of more up-to-date ICRP recommendations for dosimetry modeling purposes.

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ICRP, “Recommendations of the International Commission on Radiological Protection,” Annals of the ICRP, Vol. 1, No. 3, 1977, (ICRP Publication 26); ICRP, “Limits for Intakes of Radionuclides by Workers,” Annals of the ICRP (Part 1), Vol. 2, Nos. 3-4, 1979, (ICRP Publication 30).

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ICRP, “Report of ICRP Committee II on Permissible Dose for Internal Radiation (1959), with Bibliography for Biological, Mathematical and Physical Data,” Health Physics, Vol. 3, [1959], (Reprinted in 1975 as ICRP Publication 2).

The topic of using updated dosimetry has been raised before. In the matter of the NRC's site-specific regulations for a geologic repository for high-level radioactive waste at Yucca Mountain, for example, the Commission was aware of the potential for future updates to the ICRP's recommendations that might be available following promulgation of its regulations in 10 CFR part 63, “Disposal of High-Level Radioactive Wastes in a Geologic Repository at Yucca Mountain, Nevada.” As a consequence, rather than index the site-specific regulations to a particular version of the ICRP, the Commission alternatively allowed the DOE to use “. . . the most current and appropriate . . .” dosimetry in its performance assessment calculations, without specifying which particular version or edition of that guidance to employ. Any updated radiation and organ or tissue weighting factors, however, would need to have been incorporated by the U.S. Environmental Protection Agency (EPA) into Federal radiation protection guidance. The Commission also stated that, “Additionally, as scientific models and methodologies for estimating doses are updated, the DOE may use the most current and appropriate (

e.g.,

those accepted by the ICRP) scientific models and methodologies to calculate the TEDE. The weighting factors used in the calculation of the TEDE must be consistent with the methodology used to perform the calculation” (74 FR 10828; March 13, 2009). The specific language in current 10 CFR 63.102(o), “Concepts,” reads, in part, as follows:

After the effective date of this regulation, the Commission may allow [a licensee] to use updated factors, which have been issued by consensus scientific organizations and incorporated by EPA [U.S. Environmental Protection Agenc

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