Reforming and Modernizing the NRC's Radiation Protection Framework

NUCLEAR REGULATORY COMMISSION

10 CFR Parts 19, 20, 34, 35, 40, 50, 53, 61, 71, and 72

[NRC-2025-1140]

RIN 3150-AL47

Reforming and Modernizing the NRC's Radiation Protection Framework

AGENCY:

Nuclear Regulatory Commission.

ACTION:

Proposed rule.

SUMMARY:

The U.S. Nuclear Regulatory Commission (NRC) is proposing to amend its regulations that govern its standards for protection against radiation. These proposed revisions would address section 5(b) of Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” and would reflect the NRC's experience and other developments in the field of radiation protection since the NRC's last major revisions to these standards in 1991. In addition, the NRC is issuing for public comment draft implementing guidance.

DATES:

Comments must be submitted electronically using

https://www.regulations.gov

by 11:59 p.m. Eastern Time on August 31, 2026.

ADDRESSES:

Submit your comments, identified by Docket ID NRC-2025-1140, at

https://www.regulations.gov.

If your material cannot be submitted using

https://www.regulations.gov,

call or email the individual listed in the

FOR FURTHER INFORMATION CONTACT

section of this document for alternate instructions.

Do not include any personally identifiable information (such as name, address, or other contact information) or confidential business information that you do not want publicly disclosed. All comments are public records; they are publicly displayed exactly as received, and will not be deleted, modified, or redacted. Comments may be submitted anonymously.

Follow the search instructions on

https://www.regulations.gov

to view public comments.

You can read a plain language description of this proposed rule at

https://www.regulations.gov/docket/NRC-2025-1140.

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:

Caylee Kenny, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001; telephone: 301-415-7150; email:

Caylee.Kenny@nrc.gov.

SUPPLEMENTARY INFORMATION:

Executive Summary

A. Need for the Regulatory Action

The NRC is proposing revisions to its Standards for Protection Against Radiation to address section 5(b) of Executive Order (E.O.) 14300 and to support national policy objectives stated therein. The revisions to the NRC's Standards for Protection Against Radiation reflect the agency's reconsideration of its use of the linear no-threshold (LNT) model for assessing health effects from radiation exposure and its application of the “as low as is reasonably achievable” (ALARA) principle that is predicated on LNT. Additionally, the proposed revisions reflect the agency's consideration of shifting to a regulatory framework that uses predominately determinate radiation limits to protect from deterministic and stochastic health effects of radiation exposure. The intent of these revisions is twofold and directed at enabling the safe use of nuclear technology while maintaining reasonable assurance of adequate protection from the health effects of radiation exposure and reflecting on several decades of experience since the last major revisions to the NRC's Standards for Protection Against Radiation. In particular, as further discussed below, the proposed revisions would (1) address unnecessary conservatism and excessive subjectivity in regulatory requirements as they relate to protection from very low doses of radiation, and (2) apply the NRC's considerable regulatory experience to incorporate flexibility and acceptable alternatives in the regulations while maintaining reasonable assurance of adequate protection from the health effects of radiation exposure.

The NRC has determined that certain aspects of its radiation protection standards allow for excessive subjectivity that leads to overly conservative assessments, and thus, are in tension with the NRC's Principles of Good Regulation (see SECY-25-0031, “Mission Statement Implementation Guidance” (ML25106A351)), in particular, the “Efficiency,” “Clarity,” and “Reliability” principles. Therefore, the NRC is proposing changes to its regulations and guidance to reduce subjectivity and unnecessary burden on applicants and licensees and to increase flexibility associated with the licensing and use of nuclear technology while maintaining reasonable assurance of adequate protection of public health and safety. Specifically, the NRC has determined that the LNT model may lead to conservative implementation of radiation protection measures at low doses. Consequently, the NRC proposes to remove references to the ALARA principle, which rests on the LNT model's assessment of risks from very low doses of radiation, from its regulations; instead, the NRC would apply a less-subjective, graded approach to managing doses below regulatory limits.

Since the proposed changes would predominantly affect regulations in title 10 of the

Code of Federal Regulations

(10 CFR) part 20, “Standards for Protection Against Radiation,” they would impact all categories of NRC licensees, and, to the extent that the affected regulations are required for an adequate and compatible Agreement State program, these proposed changes would impact Agreement States. In addition, the proposed changes would support the safe use and deployment of nuclear technologies while continuing to maintain reasonable assurance of adequate protection of individuals and are founded on a holistic consideration of the NRC's regulatory experience and the current state of science using a weight of scientific evidence decision-making approach, as described in E.O. 14303, “Restoring Gold Standard Science.”

B. Major Provisions

Major provisions of the proposed rule are the following:

1. Remove ALARA requirements from the regulations in 10 CFR Chapter I, and apply a graded approach to dose management framework that involves determinate thresholds for radiation protection, methods for dose management, and acceptable dosimetry methods.

2. Establish a process, called the planned occupational dose limit extension, whereby individuals can exceed certain annual occupational dose limits as long as certain actions are taken and the resultant doses are maintained below multiyear limitations.

3. Introduce a reporting threshold for required monitoring results related to occupational dose limits.

4. Replace unplanned overexposure reporting criteria for public and occupational effective dose limits with a 5-year dose assessment.

5. Allow for variances in public dose limits and/or accessible dose rates on a case-by-case basis, with the implementation of adequate controls.

6. Enable the optional use of modern dose modeling/calculation methods.

7. Apply a 10-rem design-basis accident acceptance criterion to consequence analyses in Regulatory Guide (RG) 1.183 and retire the use of the “well-within” and “small fraction of” standards.

8. Allow licensees to use NRC-approved devices for respiratory protection and certain deviations for these devices without separate licensing actions.

9. Introduce revised threshold/constraint for control of radiological effluents to ensure ample margin with the public dose limit and support of environmental policy objectives, while providing a burden reduction and flexibilities for licensees.

C. Costs and Benefits

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

• Cost savings to the industry of approximately $9.53 million/year at a 7 percent discount rate.

• Cost savings to the Agreement State regulators of approximately $244,000/year at a 7 percent discount rate.

• Cost savings to the NRC of approximately $704,000/year at a 7 percent discount rate.

• The draft regulatory analysis also includes a qualitative discussion of factors that were not quantifiable, including precise cost savings and benefits, if the NRC adopts the rule.

The draft regulatory analysis finds that this proposed rule provides cost savings while maintaining exposure to ionizing radiation within safe limits.

For more information, please refer to the draft regulatory analysis cited in the Availability of Documents section.

Table of Contents

I. Obtaining Information and Submitting Comments

A. Obtaining Information

B. Submitting Comments

II. Executive Order 14300: Ordering the Reform of the Nuclear Regulatory Commission

III. Background

IV. Discussion

V. Specific Requests for Comments

VI. Availability of Guidance

VII. National Environmental Policy Act

VIII. Regulatory Flexibility Certification

IX. Regulatory Analysis

X. Backfitting and Issue Finality

XI. Cumulative Effects of Regulation

XII. Plain Writing

XIII. Paperwork Reduction Act

XIV. Coordination With NRC Agreement States

XV. Compatibility of Agreement State Regulations

XVI. Voluntary Consensus Standards

XVII. Incorporation by Reference—Reasonable Availability to Interested Parties

XVIII. Executive Orders

A. Executive Order 12866: Regulatory Planning and Review (as Amended by Executive Order 14215, Ensuring Accountability for All Agencies)

B. Executive Order 14154: Unleashing American Energy

C. Executive Order 14192: Unleashing Prosperity Through Deregulation

D. Executive Order 14267: Reducing Anti-Competitive Regulatory Barriers

E. Executive Order 14270: Zero-Based Regulatory Budgeting To Unleash American Energy

XIX. Availability of Documents

I. Obtaining Information and Submitting Comments

A. Obtaining Information

Please refer to Docket ID NRC-2025-1140 when contacting the 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 Website:

Go to

https://www.regulations.gov

and search for Docket ID NRC-2025-1140.

•

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

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

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

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

PDR.Resource@nrc.gov.

For the convenience of the reader, instructions about obtaining materials referenced in this document are provided in the “Availability of Documents” section.

•

NRC's PDR:

The PDR, where you may examine and order copies of publicly available documents, is open by appointment. To make an appointment to visit the PDR, please send an email to

PDR.Resource@nrc.gov

or call 1-800-397-4209 or 301-415-4737, between 8 a.m. and 4 p.m. Eastern Time, Monday through Friday, except Federal holidays.

•

Public Meeting:

The NRC will conduct a public meeting to describe the proposed amendments and answer questions from the public on this proposed rule. The NRC will publish a notice of the location, time, and agenda of the meeting on the NRC's public meeting website within 10 calendar days of the meeting. Stakeholders should monitor the NRC's public meeting website for information about the public meeting at:

https://www.nrc.gov/public-involve/public-meetings/index.cfm.

B. Submitting Comments

Comments must be submitted using

https://www.regulations.gov

by 11:59 p.m. Eastern Time on August 31, 2026. Please include Docket ID NRC-2025-1140 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

https://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. Executive Order 14300: Ordering the Reform of the Nuclear Regulatory Commission

On May 23, 2025, President Donald J. Trump signed Executive Order (E.O.) 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” which requires the NRC to take a number of actions to help provide the American people with safe, abundant nuclear energy. Section 2, “Policy,” of E.O. 14300 sets forth the policy of the United States to (a) reestablish the United States as the global leader in nuclear energy; (b) facilitate increased deployment of new nuclear reactor technologies; (c) facilitate the expansion of American nuclear energy capacity from approximately 100 gigawatts (GW) in 2024 to 400 GW by 2050; (d) employ emerging technologies to safely accelerate the modeling, simulation, testing, and approval of new reactor designs; (e) support the continued operation of, and facilitate appropriate operational extensions for, the current

nuclear fleet, as well as the reactivation of prematurely shuttered or partially completed nuclear facilities; and (f) maintain the United States' leading reputation for nuclear safety. Section 5, “Reforming and Modernizing the NRC's Regulations,” of E.O. 14300 requires the NRC to undertake a review and wholesale revision of its regulations and guidance documents as guided by the policies set forth in section 2 of the E.O. This rulemaking addresses section 5(b) of E.O. 14300, which requires the NRC to “reconsider reliance on the linear no-threshold (LNT) model for radiation exposure and the `as low as reasonably achievable' standard, which is predicated on LNT,” and states, “[i]n reconsidering those limits, the NRC shall specifically consider adopting determinate radiation limits.” A fulsome explanation of how this rulemaking addresses section 5(b) of E.O. 14300 is provided next.

III. Background

Introduction

The NRC is proposing revisions to its standards for protection against radiation to address section 5(b) of Executive Order (E.O.) 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” to support the national policy objectives stated in that E.O. and to improve the regulation of the civilian nuclear energy industry, consistent with the aims of the Accelerating Deployment of Versatile, Advanced Nuclear for Clean Energy Act of 2024 (ADVANCE Act). All NRC licensees are subject to the NRC's radiation protection requirements set forth in title 10 of the

Code of Federal Regulations

(10 CFR) part 20, “Standards for Protection Against Radiation.” These requirements are designed to protect both members of the public and occupational workers from harm that could be caused by exposure to radiation resulting from a licensee's use of radioactive materials. The proposed revisions to the NRC's standards for protection against radiation reflect the agency's reconsideration, based on current scientific knowledge and regulatory experience, of its use of the linear no-threshold (LNT) model for assessing health effects from radiation exposure and its use of the “as low as is reasonably achievable” (ALARA) principle that is predicated on the LNT model. Additionally, the proposed revisions reflect the agency's consideration of shifting to a regulatory framework that uses predominately determinate radiation limits to protect from deterministic and stochastic health effects of radiation exposure. These proposed revisions are twofold and reflect the NRC's several decades of experience since the last major revisions to 10 CFR part 20 and would enable the safe use of nuclear technology while maintaining reasonable assurance of adequate protection from the health effects of radiation exposure. Specifically, the proposed revisions would (1) address unnecessary conservatism and excessive subjectivity associated with regulatory requirements as they relate to protection from very low doses of radiation, and (2) incorporate flexibility and acceptable alternatives in the regulations.

At present, there are several factors, such as global competition in the development of advanced, energy-intensive technologies like artificial intelligence, that—combined with a national emergency in energy production as described in E.O. 14156, “Declaring a National Energy Emergency”—demand urgent action by the NRC to ensure that the NRC continues to enable the safe use of nuclear technology while maintaining reasonable assurance of adequate protection of the public health and safety. Historically, when establishing or revising its standards for protection against radiation, the NRC, as well as its predecessor, the Atomic Energy Commission (AEC), has stated that the standards are subject to change, considering factors such as the development of new scientific knowledge or further regulatory experience (see 22 FR 549, Jan 29, 1957 and 56 FR 23360, May 21, 1991).

As a result of its consideration of current scientific knowledge and regulatory experience, the NRC has determined that certain aspects of its standards for protection against radiation allow for excessive subjectivity that leads to overly cautious assessments regarding radiological risk and methods to mitigate that risk, and that some aspects of the standards are susceptible to selective or inconsistent enforcement. Such an outcome is inconsistent with the NRC's Principles of Good Regulation, in particular, the “Efficiency,” “Clarity,” and “Reliability” principles. Specifically, correcting over-conservatisms in the NRC's regulatory framework would help ensure that the NRC's regulatory activities are consistent with the degree of risk reduction achieved, and increasing objectivity would help ensure that regulated entities and the public are more readily able to understand NRC requirements and plan activities accordingly. Moreover, a more objective regulatory framework would contribute to increasing accountability for the NRC in fairly administering its radiation protection standards and lend stability to nuclear regulation. Therefore, the NRC is proposing changes to its regulations and guidance that reduce subjectivity in the implementation and enforcement of the NRC's regulations, reduce unnecessary burden on licensees, and increase flexibility associated with the licensing and use of nuclear technology, all while maintaining reasonable assurance of adequate protection of the public health and safety.

Since the proposed changes would predominantly affect regulations in 10 CFR part 20, they would apply to all categories of NRC licensees. To the extent that the affected regulations must be adopted for an Agreement State to maintain an adequate and compatible Agreement State program, these proposed changes would impact Agreement States. The proposed changes would support the safe use and deployment of nuclear technologies while continuing to maintain reasonable assurance of adequate protection of individuals. The proposed changes are based on a comprehensive evaluation of the NRC's regulatory experience and the current state of scientific knowledge using a weight of scientific evidence decision-making approach, as described in E.O. 14303, “Restoring Gold Standard Science.”

Radiation Protection Standards

Current Standards for Protection Against Radiation

The NRC's standards for protection against radiation in 10 CFR part 20 were last significantly revised in 1991 (56 FR 23360, May 21, 1991), with minor revisions being implemented since that time. For example, the NRC introduced changes in areas such as license termination criteria and respiratory protection in 1997 (62 FR 39058, July 21, 1997) and 1999 (64 FR 54543, October 7, 1999), respectively. In short, the 1991 revisions culminated with the Commission adopting, with some exceptions, the 1977 recommendations from International Commission on Radiation Protection (ICRP) Publication 26. These revisions marked a significant departure from the approach to radiation protection that the NRC and its predecessor, the AEC, had followed since the 1950s. The most significant technical change was the adoption of the concept of “effective” dose, a concept that uses a series of correction factors to translate the risk associated with any type of radiation exposure to a dose as if it were given to the entire body. Effective dose is particularly

important for predicting and limiting the stochastic effects of radiation exposure (

i.e.,

health effects, such as cancer, whose occurrence is random in nature). As described in the proposed rule for the 1991 revisions of 10 CFR part 20 (51 FR 1092, May 21, 1991), prior to those revisions, regulatory limits were derived from implicit judgements on health effects associated with the use of licensed materials; but in the 1991 revisions, these limits were derived from an increased understanding of the risk of health effects from radiation exposure. For example, the 1991 revisions set the occupational limit for stochastic effects such that the risk of a worker dying from cancer that resulted from occupational exposure to radiation was roughly equivalent to the mortality risk experienced by workers in industries not involving radiation exposures.

As described in the NRC's 1991 final rule, the radiation protection standards were revised based on the following key assumptions: (1) within the range of exposure conditions usually encountered in radiation work, there is a linear relationship, without threshold, between dose and the probability of stochastic health effects (such as latent cancer and genetic effects) occurring; (2) the severity of each type of stochastic health effect is independent of dose; and (3) nonstochastic radiation-induced health effects (

i.e.,

health effects whose occurrence is not random in nature, but rather is based on exceeding an empirically determined threshold dose) can be prevented by limiting exposures so that doses are below the thresholds for their induction. The first and second assumptions imply that the potential health risk associated with radiation exposure is proportional to the dose received and that there is an incremental health risk associated with even small doses. Additionally, the second assumption implies that the severity of a stochastic health effect is not related to the radiation dose received by an individual. Finally, the third assumption implies that there are some health effects for which there is a threshold, meaning that the health effect does not occur if the dose to an individual remains below that threshold value. For such nonstochastic effects (now known as tissue effects), determinate limits are appropriate because the threshold for the effects can be reliably established through observation or experimentation, and thus, a limit can be established below which the effect would not occur.

As it relates to stochastic effects, when the NRC issued its 1991 revisions, the Commission observed, based on studies available at the time, that “there is an increased incidence of certain cancers associated with radiation exposure at high doses and high dose rates. However, whether these effects occur at very low doses and, if they occur, whether their occurrence is linearly proportional to dose are not firmly established.” Therefore, the NRC determined that as a policy matter, in the absence of convincing evidence that there is a dose threshold or that the health effects of low levels of radiation are fully understood, the LNT model for cancers and genetic effects was appropriate for formulating radiation protection standards and planning radiation protection programs.

Developments in Radiation Protection Relevant to the NRC's Radiation Protection Regulatory Framework

ICRP Publication 26

The ICRP is an independent organization of members in all fields of radiation protection. It publishes recommendations and guidance regarding radiation protection.

In ICRP Publication 26, the ICRP provided its 1977 recommendations. This was a watershed event in the field of radiation protection. Prior to these recommendations, much of radiation protection was based on limiting the external exposure to individuals and limiting the amount of intake of radioactive materials to radionuclide-specific maximum concentration levels. With the 1977 recommendations, the ICRP introduced the distinction between stochastic health effects and nonstochastic health effects, and it also introduced several new quantities for measuring radiation dose (

i.e.,

equivalent dose and effective dose). Thereafter, the primary focus of radiation protection became protection from those effects that show a threshold and thus whose occurrences are not random in nature (

i.e.,

nonstochastic, or tissue, effects) and protection from those effects that do not show a threshold and whose occurrence is random in nature (

i.e.,

stochastic effects), as opposed to the older approach that essentially focused on protection from internal and external exposures. In ICRP Publication 26, to assess the level of risk, the health effects of internal and external exposures were combined into the concept of effective doses, a quantity that is weighted for types of radiation and organs irradiated, as applicable. This system was largely adopted by the NRC in its 1991 revisions to 10 CFR part 20 and has served as the basis for the NRC's radiation protection regulatory framework ever since.

ICRP Publication 60

At the time that the NRC was developing its 1991 revisions to 10 CFR part 20, the ICRP was in the process of revising its 1977 recommendations. This culminated with the issuance of ICRP Publication 60 in which the ICRP introduced several refinements to the 1977 methods for calculating doses and recommended revised limits for members of the public and occupationally exposed individuals. As it pertains to the recommended public dose limits, the ICRP initially published its new recommendations in 1985. During the development of its 1991 revisions to 10 CFR part 20, which occurred throughout the 1980s, the NRC integrated the new ICRP recommendations for exposure of members of the public into the 1991 rule.

With regard to the occupational dose limit for stochastic effects, the ICRP reduced its recommended limit from 5 rem/year (50 mSv/year) to 2 rem/year (20 mSv/year) averaged over 5 years, not to exceed 5 rem (50 mSv) in any single year. The NRC decided not to follow this recommendation in the 1991 rule for exposure of workers, based on the NRC's regulatory experience. With ICRP Publication 60, the ICRP also introduced changes to several quantities that are significant to dosimetry calculations. For example, the radiation weighting factor was introduced to replace the quality factor in the conversion of absorbed dose to equivalent dose (called dose equivalent in ICRP Publication 26). This change improved the accuracy of calculations because, rather than calculating the biological effects at a given point in an organ as was done with the quality factor, the radiation weighting factor provides values that are averaged over an entire organ. Additionally, several subsequent supporting publications for ICRP Publication 60 (

e.g.,

ICRP Publication 67) sought to improve the biokinetic models used to calculate doses and to provide updated derived limits, like annual limits on intake and radionuclide-specific dose conversion factors.

ICRP Publication 103

The most recent updates to the ICRP's comprehensive recommendations for a system of radiological protection, as of 2026, are contained in ICRP Publication 103, published in 2007. In ICRP Publication 103, the ICRP maintained its recommended dose limits and maintained justification, limitation, and optimization as the fundamental principles of radiation protection.

Additionally, the ICRP updated its recommended tissue weighting factors and its recommended methodology for accounting for detrimental impacts on overall health, and it provided a framework for demonstrating radiological protection of the environment. The NRC has not incorporated the recommendations in ICRP Publication 103 as requirements into its regulations; however, as explained in the sections describing the proposed regulations at § 20.1010 and at Appendix H to 10 CFR part 20, the NRC proposes in this rulemaking to allow applicants and licensees to use dosimetry modeling approaches that differ from those underlying the current 10 CFR part 20, including those that result from ICRP Publication 103.

NCRP 180 and Commentaries 26 and 27

The National Council on Radiation Protection and Measurements (NCRP) is a technical organization dedicated to the development of recommendations that pertain to public policy involving radiation protection. The NCRP holds a Congressional Charter under Public Law 88-376 to support radiation protection by providing independent analysis, information, and recommendations.

The NCRP's latest major set of recommendations for managing exposure to ionizing radiation is provided in NCRP 180, published in 2018. NCRP 180 is largely consistent with the recommendations in ICRP Publication 103 and reflects advances in the understanding of the biological effects of ionizing radiation that have accrued since the NCRP published its last major set of recommendations in 1993. In NCRP 180, the NCRP concluded that the consensus understanding of radiation effects has not changed in a way that significantly impacts recommended numeric protection criteria from the 1990s—which are consistent with the NRC's current regulations—except potentially in the case of dose to the lens of the eye. Specifically, the NCRP recognized that there is a growing body of evidence that health effects to the lens of the eye may occur at lower dose levels than previously estimated, potentially impacting currently accepted threshold values. Additionally, the NCRP observed that some research indicates that vision-impairing cataracts might be better characterized as a stochastic health effect rather than a tissue effect (

i.e.,

a nonstochastic effect that is subject to a threshold). On this topic, NCRP Commentary 26 (2016) recognizes that available data does not yet support a quantitative estimate of a new threshold value.

Separately, the current observations from the ICRP, in ICRP Publication 118, concluded that a nominal threshold of 50 rad (0.5 Gy) for the lens of the eye is appropriate. NCRP Commentary 26 provides updated guidance on radiation dose limits for the lens of the eye, reflecting new scientific evidence on cataract formation at lower doses. The commentary recommends reducing the occupational dose limit for the lens of the eye from 15 rem/year (150 mSv/year) to 5 rem/year (50 mSv/year). This recommendation aligns with international recommendations, including those from the ICRP. However, at the time of this rulemaking, these findings are preliminary and the recommendations are conservative in nature, especially when considering that the current annual limit on dose to the lens of the eye is already less than half of the new nominal threshold observed by the ICRP. Further research in this area may merit reconsideration of the current occupational dose limit for the lens of the eye in the future.

Recent Rulemaking Activity Pertaining to 10 CFR Part 20

In April 2002, the NRC staff commenced an effort to update 10 CFR part 20 to align with what would become the ICRP Publication 103 recommendations. With SECY-01-0148, “Processes for Revision of 10 CFR part 20 Regarding Adoption of ICRP Recommendations on Occupational Dose Limits and Dosimetric Models and Parameters” (ML011580363), the staff presented the Commission with options and recommendations for agency action in response to radiation protection-related information that had been developed since the last major revisions to 10 part 20 in 1991. In response, the Commission directed the staff to coordinate with other Federal agencies to ensure that a coherent approach would be applied to the use of updated radiation protection-related information and to monitor the work of the ICRP as it develops what would become ICRP Publication 103.

In December 2008, after the release of ICRP Publication 103, the NRC staff, in SECY-08-0197, “Options to Revise Radiation Protection Regulations and Guidance with Respect to the 2007 Recommendations of the International Commission on Radiological Protection” (ML091310193), recommended that the NRC's radiation protection framework be amended to align with ICRP Publication 103. As part of that recommendation, the staff observed that rulemaking would not begin immediately because information required for developing the technical basis for the rulemaking and the regulatory analysis was not available at the time. In response, the Commission directed the staff to “immediately begin engagement with stakeholders and interested parties to initiate development of the technical basis for possible revision of the NRC's radiation protection regulations, as appropriate and where scientifically justified, to achieve greater alignment with the 2007 recommendations of the [ICRP] contained in ICRP Publication 103.”

In April 2012, after much stakeholder engagement regarding potential changes to the NRC's radiation protection regulatory framework, the NRC staff, in SECY-12-0064, “Recommendations for Policy and Technical Direction to Revise Radiation Protection Regulations and Guidance” (ML121020108), communicated to the Commission policy recommendations and the technical basis for revisions to that framework. In response, the Commission approved the development of a regulatory basis for the revision of 10 CFR part 20 and 10 CFR part 50, Appendix I to align those regulations with the most recent methodology and terminology for dose assessment. However, the Commission disapproved the staff recommendations to develop a basis for reducing the limit on occupational total effective dose equivalent and to eliminate the use of traditional units in favor of International System of Units (SI) for radiological measurement. The Commission also directed the staff to continue discussions with stakeholders regarding dose limits for the lens of the eye and for the embryo/fetus. Finally, the Commission directed the staff to continue discussions with stakeholders on alternative approaches regarding radiological protection for individuals at or near the dose limit.

Subsequently, in July 2014, the NRC staff published an advance notice of proposed rulemaking (ANPR) (79 FR 43284, July 25, 2014) to obtain input on its proposed approach to the rulemaking. In response to the ANPR, the NRC received 90 individual comments and about 3,000 form letters. The staff assessed that most of the comments were not supportive of the revision to 10 CFR part 20 in large part because of doubts regarding the safety benefits of the proposed changes when weighed against the costs of implementing the proposed changes.

Finally, in December 2016, as described in SECY-16-0009, “Recommendations Resulting from the Integrated Prioritization and Re-Baselining of Agency Activities” (ML16028A189), and its accompanying

Federal Register

notice (81 FR 95410), as part of an agencywide reprioritization initiative, the NRC discontinued this rulemaking activity—having concluded that, “the current NRC regulatory framework continues to provide adequate protection of the health and safety of workers, the public, and the environment.”

Petition for Rulemaking Regarding the Linear No-Threshold Model and Standards for Protection Against Radiation

In February 2015, the NRC received three petitions for rulemaking (PRMs) requesting that the NRC amend 10 CFR part 20 to discontinue the use of the LNT model as the primary scientific basis for the NRC's radiation protection standards. The NRC published a

Federal Register

notice docketing the PRMs (80 FR 35870, June 23, 2015) and requested public comments. The PRMs sought several specific changes to the regulations, such as the increase of the occupational dose limit from 5 rem to 10 rem; the removal of the concept of ALARA based on the assertion that radiation exposure is beneficial at low doses; the increase of the public dose limit so that it would match the proposed occupational dose limit; and the ending of the use of lower dose limits for pregnant women, an embryo/fetus, and children under 18 years of age.

Upon consideration of the PRMs and associated comments from the public and other governmental agencies and the relevant positions of authoritative scientific bodies, the NRC denied the PRMs. In its denial (86 FR 45923, August 17, 2021), the NRC reviewed the scientific basis for its current regulatory framework and the relevant recent research in the area. A key basis asserted by the PRMs was the concept of hormesis (

i.e.,

that low doses of radiation are beneficial to humans), and that, because of this, the NRC's regulatory framework should be revised to reflect the beneficial nature of low dose exposures for workers and members of the public.

The NRC ultimately denied the PRMs, noting, “There is scientific uncertainty and no compelling evidence as to whether the hormesis concept is valid for application to radiation protection requirements. None of the national and international authoritative scientific advisory bodies . . . support the hormesis concept as a regulatory model for radiation protection” (86 FR 45923). With respect to the argument in the PRMs that the concept of ALARA should be removed from the NRC's regulations, the NRC described the intended implementation of ALARA as involving the concept of reasonableness (

i.e.,

“making `every reasonable effort' to implement ALARA . . . to the `extent practical' ”). Notwithstanding public comments regarding the PRMs, which argued that the NRC's implementation of ALARA has led to excessive costs to licensees and has inhibited the growth and innovation of the nuclear sector, the denial explained that compliance with the ALARA requirement is based on whether the licensee has incorporated reasonable measures to track and, if necessary, to reduce exposures—not whether exposures and doses represent an absolute minimum or whether the licensee has used all possible methods to reduce exposures.

While this description of the ALARA requirement remains true today, the NRC recognizes that there have been challenges in the implementation of the ALARA requirement, namely a lack of clarity of when dose reduction is deemed sufficient, excessive subjectivity, and susceptibility for selective or inconsistent enforcement. For example, there is wide variance within the U.S. nuclear industry in how much a given licensee is willing to spend to reduce radiation exposure and regulatory experience indicates that, in general, these industry-determined benchmarks significantly exceed the value promulgated by the NRC in NUREG-1530. Accordingly, the direction in section 5(b) of E.O. 14300 provides an opportunity for the Commission to correct the implementation issues associated with ALARA, consistent with the “Efficiency,” “Clarity,” and “Reliability” principles of the NRC's Principles of Good Regulation.

NRC Response to E.O. 14300 Section 5(b)

The NRC considers its current standards for protection against radiation to be science-based to the extent that adequate methods and analyses have been applied in the works that have been referenced in the development of the NRC's regulations and guidance. However, as has been known for many decades, the uncertainty associated with dosimetric models and methods increases significantly in the low dose range. This is largely because these models and methods rely in part on extrapolations from high-dose and high-dose-rate data as the primary basis for estimation of radiation-related risk at low doses. Such extrapolations of epidemiological data do not fully account for what is known to be a complex, and likely adaptive, cellular response to doses in the low dose range—which includes levels common to NRC-licensed activities—thus, a degree of scientific judgement is used to account for these effects.

Difficulties with using epidemiological data to estimate radiation-related risk at low doses can be attributed to multiple factors. For example, there is difficulty in conducting epidemiological studies with sufficient statistical power to control for confounding factors such as lifestyle choices (

e.g.,

smoking and diet) and population health in order to distinguish between cancers caused by very low level radiation and the large baseline cancer rate to which humans are subjected. For example, Table 12-4 of the BEIR VII Phase 2 report shows that 20 percent of the U.S. population is expected to die from solid cancers (

i.e.,

excluding blood cancers like leukemia). This large baseline cancer rate essentially introduces a signal-to-noise problem with the “signal,” or the fatal cancers from very low doses of radiation, are masked by the large “noise,” from the baseline fatal cancer rate. From a radiobiological perspective, there are unknowns involving cellular defense mechanisms and how these mechanisms modify the long-term health effects of radiation exposure. The scientific community has sought to address these uncertainties in part by adjusting the slope of the linear approximation of the dose-response relationship through the use of a dose and dose rate effectiveness factor (DDREF). However, the appropriate value of the DDREF is itself subject to uncertainty and is the result of scientific judgement. More importantly, the implementation of the DDREF has not had a practical impact on recommended radiation limits or upon curtailing practices that seek to reduce radiation risk by minimizing exposures even to very low doses.

Thus, while the methods used to establish the basis for the NRC's radiation protection standards are sound, and while these standards are protective of the public health and safety, there are uncertainties associated with the methods and resulting recommendations within consensus-based standards, including their exact degree of conservatism. Regulatory experience, though, has demonstrated that the primary issue is not the standards themselves, but their implementation. For example, those standards that go beyond what is necessary for reasonable assurance of adequate protection and that can be interpreted as requiring continuous dose reductions even to very low doses of radiation have often been applied

without a reasonable stopping point. In these instances, the radiation protection standards have led to outcomes that are overly conservative. As a practical matter, such over conservatism can significantly undervalue the benefits of activities when compared to their risks, sometimes at great economic costs or stifling of innovation.

Reconsideration of LNT and ALARA

The LNT model of radiation protection has led to confusion regarding the risks associated with low doses of radiation exposure and to unintended consequences as it relates to the costs associated with radiation protection at levels common to NRC-licensed activities. This model is used to account for the stochastic nature of some radiogenic health effects. It combines knowledge from epidemiological data from atomic bomb survivors and other cohorts and radiobiological research results to establish a relationship between the amount of radiation dose that a human receives and the health outcome, in particular cancer. The ICRP describes how epidemiological data from high doses are used to predict risk at very low doses:

The LNT model receives considerable, although not decisive, support from epidemiological studies of radiation-related cancer risk, in the same sense that the risk of mortality and morbidity from all solid cancers combined in the LSS [Life Span Study] is proportional to radiation dose down to about 100 mGy [10,000 mrad], below which statistical variation in baseline risk, as well as small and uncontrollable biases, increasingly tend to obscure evidence concerning any radiation-related risk. This uncertainty is the main reason why it is generally impossible to determine, on epidemiological grounds alone, that there is, or is not, an increased risk of cancer associated with radiation exposures of the order of a few tens of mSv [1 mSv = 100 mrem] and below. Risk estimates for such exposures are obtained through the use of mathematical models that assume a simple relationship,

e.g.,

linear, linear-quadratic, or linear with a dose and dose rate effectiveness factor (DDREF) between risk at higher doses, where epidemiological data tend to be informative, and at doses so low that direct epidemiological observation is uninformative (ICRP Publication 103, paragraph A179).

The radiation dose response relationship is commonly accepted to be linear with changes in slope at lower doses, represented by the DDREF, indicating less health impact per unit dose at lower doses. To date, no threshold has been established in this model, meaning that as the dose decreases to zero, the corresponding risk follows proportionally to zero. However, this lack of a threshold and the proportional relationship between dose and health response are commonly distilled to mean that even the lowest dose will increase the risk of cancer. While this conclusion is technically consistent with the LNT model, it is overly simplistic and leads to confusion because it discounts the effect of known biological responses to cellular upsets and the margins of error associated with slope factors and cancer coefficients that, at low levels of dose, include zero health effects as a possibility.

The NRC recognizes that the quantitative estimation of health risk at very low doses presents longstanding scientific challenges. The NRC acknowledges that advances in radiobiology have identified mechanisms such as DNA damage response and repair, dose-rate effects, and adaptive cellular responses that complicate simple linear extrapolation. However, the NRC finds that no consensus-supported, regulation-ready alternative model to the LNT model exists at this time. In the absence of such a suitable replacement, the NRC has taken this opportunity to address the LNT model's inherent limitations by carefully examining its unintended impact on ALARA practices.

Because of the LNT model's limitations in the very low dose region of the model (sometimes referred to as linear to zero), the radiation protection community has taken a layered precautionary approach, traditionally seeking to minimize radiation exposure in order to minimize the risk of stochastic health effects. Initially, the intent of this practice was to reduce dose “as low as practicable,” as described in ICRP Publication 1, the 1959 “Recommendations of the International Commission on Radiological Protection.” Subsequently, it was recast to emphasize reasonable approaches to dose reduction, first as “as low as is reasonably achievable” and then as the present-day practice of “optimization.” However, regulatory experience corroborates the observations in E.O. 14300 regarding the negative consequences of relying on subjective interpretations of reasonableness as it relates to risks from and protective measures for very low doses of radiation. The root of the matter is that there is a difference between eliminating all risks and recognizing when a risk exists but is extremely small, or even within the margin of error that includes zero risk, and that further risk reduction is not reasonable.

The ALARA principle is an outgrowth of applying the LNT model. That is, because the LNT model does not recognize a threshold below which stochastic health effects do not occur, there is an implication that dose should be minimized to also minimize the risk of health effects. However, properly understood, the ALARA principle recognizes that, unless all dose is eliminated, some risk may remain but that the level of that risk should be balanced by the reasonableness of further dose reduction measures. In contrast, over-conservatism in the application of the LNT model at very low doses combined with the potential for enforcement action for noncompliance renders implementation of the model susceptible to rote attempts at dose reduction rather than an approach tempered by a measured consideration of the reasonableness of those reductions. In essence, the reasonableness test that is supposed to be inherent to ALARA-related decision-making has gradually become an expectation that if a means of dose reduction is available, regardless of its reasonableness in relation to the total dose and the amount of reduction, it should be applied without further consideration. In practice, this has at times resulted in significant economic costs and operational and licensing inefficiencies without commensurate public health and safety gains.

This seemingly singular focus on minimizing the risk associated with very low doses is at odds with the long-standing radiation protection recommendations that established these principles in the first place. Notably, as far back as 1977, the ICRP observed that in the choice of alternative practices, radiation risk estimates should be used only with great caution and with explicit recognition of the possibility that the actual risk at low doses may be lower than that implied by a deliberately cautious assumption of linear proportionality of risk with dose.

As observed in E.O. 14300, the ALARA principle as used in the NRC's regulations has lost its intended focus on reasonableness. Instead, as a practical matter, its unbalanced application may very well contribute to more societal harm than the potential harm from the extremely low levels of radiation typical of NRC-licensed activities by hindering the consideration of nuclear technology for energy production and other uses. Therefore, while the NRC recognizes that there is insufficient evidence to refute the use of the LNT model when considering the stochastic health effects of radiation exposure, it also recognizes that the NRC's implementation of the ALARA principle as part of its use of the LNT model—in particular, the nonthreshold

aspect of the model—has led to regulatory burden that is not commensurate with the resulting public health and safety benefit and that is not consistent with the original intent of the ALARA principle.

In light of the foregoing, one purpose of this rulemaking is to restore to the NRC's regulations the original intent of the ALARA principle, which is to ensure that dose reductions below the dose limits are only required to the extent that they are reasonable and are supportive of compliance with those dose limits. The NRC proposes to do this by retiring the use of ALARA terminology in the NRC's regulations; utilizing selected aspects of the linear dose response model in favor of a strict adherence to the LNT model and its emphasis on the lack of a threshold for stochastic effects; and defining required dose management practices below dose limits, which will enable clearer and more objective decision-making regarding dose situations typical of NRC-licensed activities. Stated another way, the NRC proposes to continue to use the linear dose response model, as it continues to be the most appropriate model upon which to base a radiation protection framework; however, the NRC proposes to also detail how licensees should apply a graded approach to dose management to ensure clarity in how doses below the dose limits are to be controlled.

Through this rulemaking, the NRC proposes a complete discontinuation of the use of ALARA terminology in its regulations and guidance. The NRC has concluded that simply issuing a clarification of the intent of the ALARA principle would not be effective in achieving an enduring resolution of the issues associated with the NRC's current implementation of the ALARA principle. As previously discussed, the NRC's current implementation of the ALARA principle allows for excessive subjectivity in the expectations for dose reduction measures, oftentimes resulting in overly conservative outcomes. The proposed rule changes seek to minimize the subjectivity associated with radiation safety decision-making at the low doses typical of NRC-licensed activities. However, these rule changes will not require any changes to licensees' current practices; instead, the rule changes would clarify what is required for compliance but would not preclude licensees from choosing to do more. Therefore, in addition to providing dose limits that are sufficient for the adequate protection of workers and the public, the NRC's regulations would include requirements that are triggered at dose levels below those dose limits to ensure that the dose limits are not exceeded and that radiological hazards are adequately surveyed and controlled. These dose levels would be the basis for a graded approach to dose management.

With the recognition that the NRC's radiation protection regulatory framework is conservative as described previously, the NRC intends as an additional purpose of this proposed rulemaking to provide additional flexibility and to remove from its regulations overly cautious requirements pertaining to radiological matters. Combined with the proposed retirement of the term ALARA, the proposed changes that would enable licensee flexibility would support the NRC's mission statement by enabling the development of nuclear energy in the United States while maintaining reasonable assurance of adequate protection.

For example, the NRC proposes to reduce certain reporting requirements for radiological monitoring and certain exposure situations in excess of limits. Additionally, the NRC proposes to allow licensees to use dosimetry methods that differ from the systems that serve as the basis for certain provisions in the regulations without needing an approved exemption from those regulations. This proposed change would allow licensees to use modern approaches to dosimetry without incurring the burden and costs of an exemption request.

As it relates to public dose limits, the proposed changes would allow applicants and licensees to apply for higher limits for members of the public who enter the controlled area of a facility and to apply for higher limits for members of the public at large. The controlled area of a facility is defined in 10 CFR 20.1003 as “an area, outside of a restricted area but inside the site boundary, access to which can be limited by the licensee for any reason.” In essence, the controlled area is land that a licensee (or applicant) owns or leases (or will own or lease during the period of the license) and thus where it can legally control occupancy and impose other radiation protection measures, as necessary. Regarding occupational dose limits, the proposed changes would allow licensees to manage occupational doses using a multi-year average dose within acceptable limits without having to implement burdensome provisions associated with planned special exposures when managing the dose limits on an annual basis alone. And, again, these proposed changes would not affect current licensees that desire to continue using their existing practices. These proposed changes are described in greater detail in Section IV.

In accordance with accepted practice in the field of radiation protection, the NRC would continue to emphasize the fundamental radiation protection principles of justification, limitation, and optimization as the guideposts within its radiation protection regulatory framework. However, consistent with International Atomic Energy Agency (IAEA) General Safety Requirements Part 3 (GSR Part 3), “Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards”—which provides internationally accepted standards to ensure the protection of people and the environment—under the revisions proposed by this rule, compliance with the NRC's regulations would be taken as evidence of the application of those principles in the United States. Specifically, the principle of justification—ensuring that decisions resulting in radiation exposure do more good than harm—is satisfied by the NRC's enacting legislation, NRC regulations, and the licensing process, which ensures that licensed activities are conducted for the general welfare of the American public as authorized by law. The principle of limitation—the regulatory body establishing and enforcing dose limits—is satisfied by the dose limits in the radiation protection standards reflected in the NRC's regulations. These limits continue to be sufficient to provide reasonable assurance of adequate protection of the public health and safety and the graded approach to dose management requirement proposed in this rulemaking ensures that these limits are not exceeded. The principle of optimization—the process for ensuring that the likelihood and magnitude of exposures and the number of individuals exposed are as low as reasonably achievable, with economic, societal, and environmental factors taken into account—is satisfied by licensees complying with the precautionary requirements in the NRC's regulations, and, as applicable, applying prescribed practices when doses are below regulatory limits to maintain doses within those limits. To minimize subjectivity in implementing the principle of optimization and to avoid the overly cautious practices that resulted from the NRC's previous use of the term ALARA throughout its regulations and guidance, the NRC proposes to provide implementation guidance for a graded approach to dose management below regulatory limits.

This approach would ensure that the risk of stochastic effects is adequately controlled by ensuring that regulatory dose limits are not exceeded.

In sum, with this rulemaking, the NRC proposes to use the linear dose response model as a partial basis for its regulations and guidance but would remove from its practices the excessive conservatisms and potential for disproportionate enforcement that result from the LNT model and its emphasis on the lack of a threshold for stochastic effects. This is consistent with the NRC's continued determination that the dose limits are sufficient to provide reasonable assurance of adequate protection of the public health and safety.

Consideration of Determinate Dose Limits

As part of its response to E.O. 14300 section 5(b), the NRC considered whether to propose shifting its radiation protection regulatory framework to be based on a set of determinate dose limits. Determinate dose limits currently exist in the NRC's regulations for nonstochastic effects (tissue effects) because research has revealed that these effects do not occur below a threshold dose value. Thus, a regulatory dose limit can be derived from this threshold dose value by adding margin to the threshold value, and there would be high confidence that no health effects would occur should doses remain within that limit. Such is the case, for example, with the skin dose limit in 10 CFR 20.1201(a)(2)(ii).

Theoretically, a radiation protection regulatory framework based on determinate limits, for both nonstochastic and stochastic effects, could essentially apply a “go/no-go” regulatory approach that would deemphasize radiation protection precautions in lieu of verifications that a licensee is maintaining dose values below the applicable dose limit. In order to move to such a regulatory framework, a basis would be required to establish determinate dose limits for stochastic health effects.

At present, there is no scientific consensus establishing a threshold below which stochastic health effects do not occur. As described in SECY-12-0064, as it relates to stochastic effects, “It is unlikely there might be a threshold level of exposure below which biological response does not occur. Such a threshold could only occur if DNA repair processes were totally effective in that dose range or if a single radiation track were unable to produce an effect. The cellular processes such as apoptosis and cellular differentiation that can protect against later phases of tumorigenesis are judged to be efficient but can be bypassed; there is no reason to believe that those defenses act differently on spontaneous and radiation-induced tumors or have specific dose dependencies.”

Additionally, more recent analysis of datasets focusing on lower doses levels (

i.e.,

10 rem or less) in “Issues in Interpreting Epidemiologic Studies of Populations Exposed to Low-Dose, High-Energy Photon Radiation” (2020), concludes that the totality of scientific evidence suggests that even if a threshold for stochastic health effects existed it would not be higher than 1 rem, which is significantly below the current occupational dose limit of 5 rem per year for stochastic health effects. Such analyses reflect the evolving understanding of stochastic health effects and indicate challenges with establishing a defensible determinate threshold for these types of effects.

Furthermore, as described in ICRP Publication 103 and supporting publications such as ICRP Publication 118, “ICRP Statement on Tissue Reactions/Early and Late Effects of Radiation in Normal Tissues and Organs—Threshold Doses for Tissue Reactions in a Radiation Protection Context,” there is growing evidence that other health effects such as cataracts may show stochastic behavior, or that the threshold for the effect, if one exists, is lower than originally understood. Therefore, the NRC, after consideration of the available information, concludes that establishing a determinate regulatory dose limit for both stochastic and nonstochastic health effects and adopting a corresponding “go/no-go” regulatory approach is not currently supported by scientific evidence.

Accordingly, the NRC reaffirms its position that the linear dose response model is the most appropriate available consensus model for formulating radiation protection standards and planning radiation protection programs. However, to address deficiencies in the implementation of that model in its current radiation protection regulatory framework, the NRC proposes to provide clarity and increased objectivity to radiation protection decisions by identifying a series of threshold doses that guide actions below the stochastic dose limits. This graded approach to dose management below stochastic dose limits is aligned with the NRC's overall risk-informed approach to regulation. The general purpose of this approach is to ensure that the NRC's radiation protection regulatory framework remains in harmony with scientific consensus while being responsive to the observations in E.O. 14300 regarding the deficiencies associated with the LNT model and the implementation of the ALARA principle in the United States. The graded approach to dose management is described further in Section IV.

Summary of NRC Response to E.O. 14300 Section 5(b)

In summary, as directed by E.O. 14300 section 5(b), the NRC is reconsidering its use of the LNT model and its use of the ALARA principle. The NRC recognizes that there are limitations to the accuracy of the LNT model at very low doses, however, the NRC has also not identified a suitable alternative model. Nevertheless, it may be possible to improve how the NRC addresses the inherent limitations of the LNT model. Therefore, the NRC is proposing changes to how the LNT model is implemented in its regulations and guidance. These changes, as proposed in this rulemaking, are intended to minimize subjectivity regarding radiation protection at low doses and to make sure that the required management of dose below regulatory dose limits is subject to a more objective reasonableness standard.

Additionally, the NRC considered the use of determinate dose limits for stochastic health effects and determined that the scientific understanding of stochastic health effects does not support the establishment of such limits at this time. Instead, consistent with the original intent of the ALARA principle, the changes proposed in this rulemaking would adopt a graded approach to dose management by identifying a series of dose-based levels that would guide radiation protection decisions below regulatory dose limits.

Further, the NRC is proposing several changes to its regulations to enable flexibility and to remove overly cautious requirements, which would support the E.O. 14300 objective of enabling the development of nuclear energy in the United States while maintaining reasonable assurance of adequate protection. The changes proposed as part of this rulemaking would apply regulatory experience and licensee feedback on operational challenges to address key deficiencies in the application of the NRC's current radiation protection standards, while remaining consistent with the current scientific understanding of the health effects of radiation exposure. These changes would represent a rebaselining of applicable regulations and guidance to reduce the subjectivity that has developed over time in the implementation of the NRC's radiation

protection standards with the intent of achieving the original aims of the ALARA principle; specifically, ensuring that the management of dose below applicable dose limits is subject to an objective reasonableness standard that uses sound radiation protection principles.

Should these changes be implemented, the NRC determined that prior licensing decisions—including environmental reviews, license amendments, and approvals—that involved ALARA would remain valid because of their inherently conservative nature (

i.e.,

because of the prior implementation of the ALARA principle, they would be at least as protective as the proposed revised regulations). This is true because compliance with regulatory dose limits is sufficient to provide reasonable assurance of adequate protection for individuals and ALARA practices seek to establish reasonable margin to the limits and limit the overall risk of health effects that are stochastic in nature. Moreover, the proposed regulatory changes define what is reasonable in order to remove subjectivity on the part of licensees—so if licensees had come to these conclusions on their own, the NRC could have accepted their approaches as being commensurate with the ALARA principle at the time.

Additionally, the proposed changes are designed such that existing radiation protection programs that are compliant with the current requirements would be compliant with the proposed new requirements. Accordingly, the proposed changes would not affect current licensees that desire to continue using their existing programs.

Finally, the NRC determined that the proposed changes would maintain a radiation protection regulatory framework that is in harmony with the United States' commitments to the international community. For example, both Article 15 of the Convention on Nuclear Safety (CNS) and GSR Part 3, which serves as a standard for how countries can meet their obligations under the CNS, include the ALARA principle, with the latter discussing ALARA in its description of the concept of optimization. The graded approach to dose management proposed in this rulemaking meets the description of optimization in Requirement 11 of GSR Part 3 and, therefore, also satisfies CNS Article 15. As explained in this rulemaking, the NRC is proposing to remove references to the ALARA principle in its regulations and guidance in order to definitively move away from overly conservative practices that have developed over time in the name of ALARA and, through strictly applying the concept of optimization, return to the original intent of the ALARA principle.

IV. Discussion

Description of Proposed Changes to the Regulations

Definitions

The NRC is proposing to remove the definition of “ALARA” because that term would no longer be used within the NRC's radiation protection regulatory framework. In its place, the proposed rule would add the term “graded approach to dose management.” This term would be defined as an approach whereby progressively increasing radiation protection measures are required as prospective, or actual, radiation doses exceed determinate dose thresholds to provide reasonable assurance that the applicable regulatory limit is not exceeded. This definition reflects the NRC's determination that its regulatory dose limits are sufficient to provide reasonable assurance of adequate protection of the public health and safety and that the proposed graded approach to dose management requirement ensures that these limits are not exceeded.

The graded approach to dose management serves the purpose of ensuring that dose limits are not exceeded in large part by relying on existing precautionary regulatory requirements (

e.g.,

radiation worker training, radiological monitoring, signage and posting) to control doses below the limits. Additionally, the graded approach to dose management entails that as doses increase and become closer to the dose limits (

i.e.,

at specified determinate thresholds), increasingly more rigorous radiation protection measures would be required to ensure that the dose limits are not exceeded. NRC guidance would provide one acceptable means for establishing a graded approach to dose management, including appropriate determinate thresholds and corresponding radiation protection measures (

e.g.,

shielding, additional work planning) that are considered reasonable for the circumstances.

As discussed further in this document, the NRC is also proposing to allow the use of alternative dosimetry methods as reflected in new proposed sections of its regulations, specifically, 10 CFR 20.1010 and the associated Appendix H to 10 CFR part 20. This change necessitates that several clarifying statements be added to the definitions section of 10 CFR part 20 (

e.g.,

to the definition of airborne radioactivity area) and to other applicable sections of part 20 to account for the potential that a licensee might use alternative methods and/or alternative derived operational values such as annual limits on intakes, labeling criteria, and derived air concentrations.

Additionally, the term “dosimetry method (or system)” and its definition is proposed to be added as described later in this section. With the proposed allowance of alternative dosimetry methods, the NRC determined that it would also be necessary to provide definitions for certain terms related to dosimetry concepts that have been introduced as part of modern methodologies (

e.g.,

ICRP Publication 60). Therefore, the terms “committed effective dose”, “committed equivalent dose”, “effective dose”, “equivalent dose”, “radiation weighting factor”, and “total effective dose” and their definitions are proposed to be added to 10 CFR 20.1003.

A key difference between the dosimetry methods currently incorporated in the NRC's regulations and the newer, alternative dosimetry methods proposed to be allowed as part of this rulemaking involves a distinction between the quality factor and the radiation weighting factor. In using a radiation weighting factor to convert from an absorbed dose to an equivalent dose, the newer, alternative dosimetry methods more accurately capture the health effect on entire organs versus at a single point in the organ as is done when the quality factor is used to develop dose equivalent. Therefore, while the dosimetry methods currently incorporated in the NRC's regulations remain acceptable, the NRC is proposing to include the potential for licensees to use newer, alternative dosimetry methods.

The definitions for the terms “nonstochastic effect” and “stochastic effect” are proposed to be revised to reflect updated scientific understanding and to align the NRC definition with the Department of Energy (DOE) definition, respectively. The definition for the term “nonstochastic effect” would be amended to include the alternative term “tissue effect” to reflect modern terminology and to delete cataracts as an example of the effect in consideration of recent research that indicates that this health effect may be stochastic in nature. The definition for the term “stochastic effect” would be amended to be consistent with the DOE definition for the term in 10 CFR 835.2, which, in turn, closely matches the definition in ICRP Publication 103.

Additionally, the definition for the term “Quarter” is proposed to be revised to correct a typo; the word “consecutive” in this definition is currently misspelled.

Units of Radiation Dose

The NRC is proposing to add language to § 20.1004 to account for the potential that, with the proposed addition of the option to use alternative dosimetry methods, licensees and applicants may determine values of equivalent dose/dose equivalent and total effective dose equivalent/total effective dose and effective dose equivalent/effective dose using different dosimetry systems. As stated in paragraph 31 of ICRP Publication 60:

It is appropriate to treat as additive the weighted quantities used by the [ICRP] but assessed at different times, despite the use of different values of weighting factors. The [ICRP] does not recommend that any attempt be made to correct earlier values. It is also appropriate to add values of dose equivalent to equivalent dose and values of effective dose equivalent to effective dose without any adjustments. If values of weighting factors other than those recommended by the [ICRP] are used, this fact should be clearly stated, and the values should be explicitly given when the quantities are introduced. These weighted quantities should not be added to the [ICRP's] quantities.

The proposed new § 20.1004(e)(3) would address the possibility that a licensee or applicant may apply a custom dosimetry system with the approval of the NRC, which would be required to include provisions, and supporting justification, for tracking dosimetric quantities similar to the approach that is described in paragraph 31 of ICRP Publication 60.

Alternative Dosimetry Methods

The proposed rulemaking would define the term “dosimetry method (or system)” as “an approach for calculating the biological effects of ionizing radiation exposure in humans. The approach provides a repeatable method of converting from fundamental knowledge of radioactive decay to biological effects, typically through modeling and a series of conversion and correction factors for types of radiation emitted and interactions with tissues, organs, and the environment.” Dosimetry methods are essential to radiation protection because they provide the tools necessary to translate how the physical phenomenon of the energy imparted by radioactive decay results in an impact and potential hazard to public health and safety.

The current radiation protection standards in 10 CFR part 20 use dosimetry methods that are based, with some exceptions, on ICRP Publication 26 (and supporting publications like ICRP Publication 30), which contains the 1977 recommendations of the ICRP. Other NRC regulations and certain license conditions make use of different dosimetry methods. For example, the requirements for technical specifications regarding effluents from nuclear power reactors at 10 CFR 50.36a apply dosimetry methods established in ICRP Publication 1. Additionally, some licensees have applied for NRC approval to use derived limits that are based on more recent dosimetry methods, in particular with respect to internal dose calculations of inhaled radionuclides. The NRC has approved the use of those methods on a case-by-case basis, concluding that their use provides reasonable assurance of adequate protection of the health and safety of workers and the public and complies with applicable regulatory requirements.

Through a proposed new regulation and a proposed new associated appendix, § 20.1010 and Appendix H to 10 CFR part 20, respectively, the proposed rulemaking would give licensees and applicants the option to voluntarily use specific, alternative, dosimetry methods, without requiring a separate, case-by-case NRC review and approval, to demonstrate compliance with the NRC's radiation protection standards in 10 CFR part 20.

The NRC determined that allowing the use of alternative dosimetry methods based on specific, identified publications would offer flexibility to licensees and applicants, increase efficiency in licensing, operations, and the administration of radiation protection programs, and bring the NRC's radiation protection regulatory framework more in line with current recommendations, while maintaining reasonable assurance of adequate protection of the public health and safety. The NRC determined that this change would maintain the effectiveness of its radiation protection regulatory framework because the specific, alternative, dosimetry methods that would be preapproved for use are appropriate for the scope of activities subject to 10 CFR part 20, are technically adequate and have been published by expert, standards-setting organizations, and provide sufficient transparency regarding associated assumptions and uncertainties. The use of dosimetry methods other than these specific methods would still require case-by-case review and approval by the NRC, and acceptability criteria for requests to use such methods are proposed to be added to the NRC's regulations to streamline that process.

To these ends, the proposed new regulation, § 20.1010, would reference a listing of generically approved alternative dosimetry methods in a proposed new Appendix H to 10 CFR part 20, and it would also provide the criteria for the NRC's approval of a method that is not listed in Appendix H. The methods proposed for inclusion in Appendix H have been promulgated primarily by the ICRP, but the listing of generically approved methods would also include methods published by other consensus-setting organizations. Finally, Appendix H would list the conditions, if any, on the use of these generically approved methods. In the future, the NRC expects to update Appendix H as appropriate, including as more methods become available.

The application of alternative dosimetry methods should be described and controlled within a licensee's radiation protection program, as is required by the existing regulation at § 20.2102, such that dose assessments can be evaluated and, if necessary, reconstructed by a knowledgeable third party (

e.g.,

NRC inspector). These programs should ensure that dosimetric quantities are determined in accordance with relevant standards and, once determined, are summed in accordance with the proposed regulation at § 20.1004(e)(3).

Documents Incorporated by Reference for Proposed § 20.1010 and Appendix H to 10 CFR Part 20

Reasonable availability of documents

—As part of this rulemaking, the NRC is proposing to incorporate by reference (IBR) documents from the American National Standards Institute/American Nuclear Society (ANSI/ANS) and the International Commission on Radiological Protection (ICRP). Upon approval from the Office of the Federal Register, the documents will be available for inspection at the NRC. Contact the NRC at NRC Technical Library, Two White Flint North, 11545 Rockville Pike, Rockville, Maryland 20852; telephone: 301-415-7000; email:

Library.Resource@nrc.gov.

Material from ANSI/ANS is available for purchase from the ANSI website:

https://webstore.ansi.org/.

Material from the ICRP is available to the public for free viewing online at the ICRP publication website:

https://www.icrp.org/page.asp?id=5.

IBR Summaries

—The NRC is proposing to IBR the following documents into proposed Appendix H to 10 CFR part 20 for use as

preapproved alternative dosimetry methods per proposed § 20.1010:

ANSI/ANS, 2020. Photon and Neutron Fluence-to-Dose Conversion Coefficients. ANSI/ANS-6.1.1-2020. La Grange Park, IL: American Nuclear Society—

ANSI-ANS 6.1.1-2020 (reaffirmed 2025) provides coefficients for converting photon and neutron particle fluence to effective dose based on ICRP Publication 116 data. Separate data are used for cranial and caudal irradiation geometries. Effective dose conversion coefficients are provided in tabular form for incident monoenergetic photons having energies from 10 keV to 10 GeV and for neutrons with energies from 0.001 eV to 10 GeV. Finally, an analytical model is provided for evaluating exposures to both photon and neutron fields in the form of a fourth order polynomial with tabulated numerical coefficients corresponding to exposure geometry and energy.

ICRP, 1990. Age-dependent Doses to Members of the Public from Intake of Radionuclides—Part 1. ICRP Publication 56. Ann. ICRP 20 (2)—

ICRP Publication 56 provides an analytical framework for calculating age-dependent committed dose equivalents and effective dose equivalents to members of the public from ingestion and inhalation of radionuclides. The framework incorporates biokinetic and dosimetric models that account for physiological differences from infancy through adulthood and applies the dose calculation methods consistent with ICRP Publications 26 and 30. This report provides organ-specific dose coefficients for 18 radionuclides across six age groups (3 months, 1, 5, 10, and 15 years, and adult) using age-specific anatomical data (

e.g.,

organ masses, bone surface areas) and biokinetic parameters (

e.g.,

gastrointestinal absorption fractions, retention half-times, tissue distribution). ICRP Publication 56 is the first in a series of five reports that also includes ICRP Publications 67, 69, 71, and 72 that provides radionuclide-specific, age-dependent, dose coefficients for members of the public.

ICRP, 1993. Age-dependent Doses to Members of the Public from Intake of Radionuclides—Part 2 Ingestion Dose Coefficients. ICRP Publication 67. Ann. ICRP 23 (3-4)—

ICRP Publication 67 is part two of a series of five reports (

i.e.,

ICRP Publications 56, 67, 69, 71, and 72) that provides radionuclide-specific, age-dependent, ingestion and inhalation dose coefficients for members of the public. This report provides ingestion dose coefficients for 13 radionuclides using the framework described in ICRP Publication 56, but with tissue weighting factors from ICRP Publication 60. Additionally, the report updates age-specific, biokinetic models for the alkaline earth elements, lead, and selected transuranic radionuclides for incorporation of ICRP Publication 60 tissue weighting factors and methods and updated understanding of human biokinetics, as applicable. Lastly, the report provides recalculated ingestion dose coefficients for the radioisotopes covered by ICRP Publication 56 using the ICRP Publication 60 tissue weighting factors and methods.

ICRP, 1994. Dose Coefficients for Intakes of Radionuclides by Workers. ICRP Publication 68. Ann. ICRP 24 (4)—

ICRP Publication 68 provides dose coefficients for occupational intakes—inhalation and ingestion—of radionuclides, that applied the tissue and radiation weighting factors from ICRP Publication 60. The report incorporates the revised Human Respiratory Tract Model from ICRP Publication 66 and updated systemic biokinetic models in ICRP Publications 56 and 67. Additionally, the report addresses excretion pathways, gastrointestinal tract modeling, and provides effective dose rates for inert gases and soluble/reactive vapors.

ICRP, 1995. Age-dependent Doses to Members of the Public from Intake of Radionuclides—Part 3 Ingestion Dose Coefficients. ICRP Publication 69. Ann. ICRP 25 (1)—

ICRP Publication 69 is part three of a series of five reports (

i.e.,

ICRP Publications 56, 67, 69, 71, and 72) that provides radionuclide-specific, age-dependent, ingestion and inhalation dose coefficients for members of the public. This report provides ingestion dose coefficients for five radionuclides not covered in ICRP Publication 67.

ICRP, 1995. Age-dependent Doses to Members of the Public from Intake of Radionuclides—Part 4 Inhalation Dose Coefficients. ICRP Publication 71. Ann. ICRP 25 (3-4)—

ICRP Publication 71 is part four of a series of five reports (

i.e.,

ICRP Publications 56, 67, 69, 71, and 72) that provides radionuclide-specific, age-dependent, ingestion and inhalation dose coefficients for members of the public. This report provides inhalation dose coefficients for the radionuclides covered in ICRP Publications 56, 67, and 69 and for calcium and curium. Additionally, the report provides biokinetic models for calcium, curium, and decay products for selected radionuclides. Finally, the report provides an approach for determining absorption types in cases where material-specific, absorption type is not known.

ICRP, 1995. Age-dependent Doses to Members of the Public from Intake of Radionuclides—Part 5 Compilation of Ingestion and Inhalation Coefficients. ICRP Publication 72. Ann. ICRP 26 (1)—

ICRP Publication 72 is part five of a series of five reports (

i.e.,

ICRP Publications 56, 67, 69, 71, and 72) that provides radionuclide-specific, age-dependent, ingestion and inhalation dose coefficients for members of the public. This report provides a compilation of age-dependent committed effective dose coefficients for members of the public from intakes by ingestion and inhalation of the 31 elements covered in ICRP Publications 56, 67, 69, and 71, as well as for the 60 elements covered in ICRP Publication 68 for workers.

ICRP, 2010. Conversion Coefficients for Radiological Protection Quantities for External Radiation Exposures. ICRP Publication 116. Ann. ICRP 40(2-5)—

ICRP Publication 116 provides fluence-to-dose conversion coefficients for effective dose and organ absorbed doses from external radiation exposures, based on ICRP Publication 103 recommendations and using official computational phantoms representing the Reference Adult Male and Reference Adult Female. The report covers a broad range of radiation types and various irradiation geometries and includes coefficients for organ-specific doses, eye lens, skin, and skeletal tissues. The report includes annexes with extensive tabulated coefficients, dose-response functions, and guidance for aircraft crew dosimetry.

ICRP, 2015. Occupational Intakes of Radionuclides: Part 1. ICRP Publication 130. Ann. ICRP 44(2)—

ICRP Publication 130 provides an introduction to a series of reports that include information for calculating doses from occupational intakes of radionuclides. This report includes sections on control of occupational exposures, biokinetic models (including a revision to the human respiratory tract model that was published in ICRP Publication 66), dosimetric models, monitoring methods and programs, and general aspects of retrospective dose assessment. ICRP Publication 130 is part one of a series of five reports that also includes ICRP Publications 134, 137, 141, and 151 that provides dose coefficients for occupational intakes of radionuclides by inhalation and ingestion. This information in this series of reports was meant to replace the dose coefficients for occupational dose calculations found in ICRP Publications 30 and 68 by implementing the ICRP's recommendations in ICRP Publication 103.

ICRP, 2016. Occupational Intakes of Radionuclides: Part 2. ICRP Publication

134. Ann. ICRP 45(

3/4

), 1-352—

ICRP Publication 134 is part two of a series of five reports (

i.e.,

ICRP Publications 130, 134, 137, 141, and 151) that provides dose coefficients for occupational intakes of radionuclides by inhalation and ingestion. As part of this report series, the ICRP published an electronic database (available at

https://www.icrp.org/

) that contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions that apply to scenarios involving inhalation, ingestion, and direct input to blood. This report provides data on several individual elements and their radioisotopes, including information on chemical forms encountered in an occupational setting, decay information, and reference parameter values for input into biokinetic models. Additionally, this report provides several corrections that are applicable to ICRP Publication 130.

ICRP, 2017. Occupational Intakes of Radionuclides: Part 3. ICRP Publication 137. Ann. ICRP 46(

3/4

)—

ICRP Publication 137 is part three of a series of five reports (

i.e.,

ICRP Publications 130, 134, 137, 141, and 151) that provides dose coefficients for occupational intakes of radionuclides by inhalation and ingestion. As part of this report series, the ICRP published an electronic database that contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions that apply to scenarios involving inhalation, ingestion, and direct input to blood. This report provides data on several individual elements and their radioisotopes, including information on chemical forms encountered in an occupational setting, decay information, and reference parameter values for input into biokinetic models. Additionally, this report provides background information for dosimetry of radon progeny and dose coefficients in the electronic database referenced above.

ICRP, 2019. Occupational Intakes of Radionuclides: Part 4. ICRP Publication 141. Ann. ICRP 48(

2/3

)—

ICRP Publication 141 is part four of a series of five reports (

i.e.,

ICRP Publications 130, 134, 137, 141, and 151) that provides dose coefficients for occupational intakes of radionuclides by inhalation and ingestion. As part of this report series, the ICRP published an electronic database that contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions that apply to scenarios involving inhalation, ingestion, and direct input to blood. This report provides data on several individual elements and their radioisotopes, including information on chemical forms encountered in an occupational setting, decay information, and reference parameter values for input into biokinetic models. Additionally, this report provides several corrections that are applicable to ICRP Publication 137.

ICRP, 2020. Dose Coefficients for External Exposures to Environmental Sources. ICRP Publication 144. Ann. ICRP 49(2)—

ICRP Publication 144 provides the technical basis for the calculation of external dose-rate coefficients for environmental exposure of members of the public, as well as a tabulation of coefficients. The calculations include modeling of environmental radiation fields, computation of organ and effective dose-rate coefficients for exposures to monoenergetic photons and electrons, and the use of these data to calculate dose-rate coefficients. The report provides tables of dose-rate coefficients for selected radionuclides for use in determining external doses from submersion in water, submersion in air (1 meter above ground), and for radionuclides distributed at a depth of 0.5 g/cm

2

in soil. The supplementary material that accompanies the report provides external dose-rate coefficients for 1,252 radionuclides of the 97 elements whose decay information is provided in ICRP Publication 107. Additionally, this report provides dosimetry information for the skeleton and the skin.

ICRP, 2022. Occupational Intakes of Radionuclides: Part 5. ICRP Publication 151. Ann. ICRP 51(1-2)—

ICRP Publication 151 is part five of a series of five reports (

i.e.,

ICRP Publications 130, 134, 137, 141, and 151) that provides dose coefficients for occupational intakes of radionuclides by inhalation and ingestion. As part of this report series, the ICRP published an electronic database that contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions that apply to scenarios involving inhalation, ingestion, and direct input to blood. This report provides data on several individual elements and their radioisotopes, including information on chemical forms encountered in an occupational setting, decay information, and reference parameter values for input into biokinetic models. Additionally, this report provides effective dose rate coefficients for several radionuclides that apply to the submersion exposure pathway of occupationally exposed individuals, and it provides a description of how the contribution to dose from progeny is accounted for in this series of reports.

References to the ALARA Principle

As part of this rulemaking, the NRC is proposing to remove references to the ALARA principle from its regulations and guidance. While the implementation of the ALARA principle based on the NRC's current regulatory language has generally led to low overall radiation doses, over time it has also resulted in overly cautious dose reduction efforts beyond what are reasonable and lacking clear alignment with actual risk or benefit. As E.O.14300 observes, implementing the ALARA principle in this manner has resulted in over-conservatism likely to the detriment of nuclear technology development because it leads to an overemphasis on the reduction of risks that the state-of-knowledge identifies as being minimal. The ALARA principle has also been superseded by the concept of optimization in the system of radiation protection recommended by the ICRP. As discussed previously in this document, in response to E.O. 14300, the NRC reconsidered the use of the ALARA principle in its regulations and determined that in order to return to the original intent of the ALARA principle and to align with the more recent concept of optimization, the appropriate approach would be to replace the ALARA principle with a requirement for a graded approach to dose management. To this end, the NRC proposes to remove all instances of the term ALARA from its regulations and to specify that the original intent of the ALARA principle will be achieved through the use of a new graded approach to dose management.

The concept of optimization is defined in the 2022 IAEA Nuclear Safety and Security Glossary as, “The process of determining what level of protection and safety would result in the magnitude of individual doses, the number of individuals (workers and members of the public) subject to exposure and the likelihood of exposure being as low as reasonably achievable, economic and social factors being taken into account (ALARA).” Requirement 11 of the IAEA's GSR-3 states that, “The government or the regulatory body shall establish and enforce requirements for the optimization of protection and

safety, and registrants and licensees shall ensure that protection and safety is optimized.” Further details regarding the regulatory body's responsibilities pertaining to optimization include establishing requirements for optimization, requiring documentation addressing optimization, and the administration of constraints (or thresholds) on dose, or risk, as appropriate. The 2022 IAEA Nuclear Safety and Security Glossary describes the purpose of constraints as boundaries in defining the range of options in optimization.

As discussed previously in this notice, in order to address the problems of subjectivity and over-conservatism that were introduced over time through the implementation of the references to the ALARA principle throughout the NRC's regulations, the NRC proposes removing these references and replacing them with a requirement for a graded approach to dose management, which would essentially be an application of the concept of optimization that, below the dose limits, relies on various existing regulatory requirements as well as licensees' individual radiation protection programs to manage dose. NRC guidance would provide an acceptable approach for this. The graded approach to dose management would rely on a series of threshold doses below the regulatory dose limits and dose management actions to be taken at each threshold dose. These threshold doses and dose management actions would generally correspond to existing requirements in 10 CFR part 20 or other regulations and, therefore, should already be incorporated within the radiation protection programs of existing licensees to a degree “commensurate with the scope and extent of licensed activities” as is currently required by § 20.1101.

For any occupational exposure scenario, compliance with 10 CFR part 20 would provide both optimization and reasonable assurance of adequate protection from radiation exposure up to and including planned special exposure events and the proposed planned occupational dose limit extensions. For example, licensees are required to conduct surveys, control access to certain areas, store material appropriately, and use signs, postings, and labels to warn workers of radiological hazards. These provisions are in effect for the full spectrum of radiological hazards that a licensee could encounter during the course of its licensed activities, and thus, these provisions form the first set of dose management actions below the regulatory dose limits that would be credited as part of a graded approach to dose management.

Under a graded approach to dose management, additional dose management actions would apply as radiological hazards increase and move closer to the applicable regulatory dose limit. The dose levels corresponding to dose management actions are threshold doses in that they represent determinate boundaries above which a specific action is required and below which they are inapplicable (

i.e.,

there is no subjectivity to when a specific dose management action should be taken). Examples of these progressively increasing, threshold doses for occupational exposure are: expected doses of 100 mrem/year, 500 mrem/year, and 5 rem/year. Specifically, above an expected dose of 100 mrem/year, licensees are required to provide instructions to workers (

i.e.,

radiation worker training) per 10 CFR 19.12; above an expected dose of 500 mrem/year, or, more specifically, 10 percent of the applicable limit, licensees are required to monitor doses to individual workers per 10 CFR 20.1502; and above an expected dose of 5 rem/year (

i.e.,

the regulatory dose limit), licensees can exercise the proposed new planned occupational dose limit extension of § 20.1205 or the existing planned special exposure process of § 20.1206, if the situation requires higher dose.

The NRC is developing guidance to further explain and provide acceptable approaches for implementing the graded approach to dose management, including alternative radiation protection measures not already set out in the NRC's regulations that would help ensure that dose limits are not exceeded. The NRC's guidance would explain that it would be acceptable for radiation protection measures under the graded approach to dose management to be supported by a comparison of the cost of the radiation protection measure (

e.g.,

shielding, additional workers, robotics) to a reasonably calculated cost-basis of an averted person-rem. The proposed guidance would provide that one example of a reasonable cost-basis standard is provided in NUREG-1530, “Reassessment of NRC's Dollar Per Person-Rem Conversion Factor Policy.” Specifically, in that guidance document, the NRC establishes the cost of an averted person-rem by multiplying a value of a statistical life coefficient—a factor that corresponds to society's willingness-to-pay for small reductions in a particular mortality risk—by a cancer mortality risk coefficient. The nominal cost of an averted person-rem under this standard is $5,200 (in 2014 dollars). Taken together, this means that it would be acceptable for considering under the graded approach to dose management whether additional radiation protection measures are reasonable based on a need to spend $5,200 to avoid a person-rem of exposure. Consequently, if a radiation protection measure were more costly than that, the licensee would have an acceptable cost-justified basis for not implementing the measure and instead accruing the dose as long as that dose is within the regulatory dose limits or, if applicable, the licensee complies with the provisions regarding planned occupational dose limit extensions or planned special exposures. In this manner the graded approach to dose management would maintain occupational dose below the regulatory dose limits while replacing the subjectivity of the current ALARA-based regulations with objective cost-benefit analyses. This guidance would be issued subsequent to this rulemaking as part of the NRC's planned two-phased approach to issuing guidance associated with this rulemaking, see Section VI, “Availability of Guidance,” for more information.

As part of this rulemaking, the NRC also proposes to require a graded approach to dose management with respect to public dose in place of the existing implementation of the ALARA principle. The objective is to maintain a layered protective approach to potential public dose as a precautionary measure. Public dose differs from occupational exposure in several key respects. First, the dose to individual members of the public is generally calculated based on an exposure scenario, whereas occupationally exposed individuals are usually monitored. For example, with respect to nuclear power plant effluents, the member of the public is assumed to be a hypothetical maximally exposed individual who represents the maximum exposure regarding food consumption, occupancy, and other usage in the vicinity of the plant site. Another example is that for a waiting room in a medical facility, the facility may conduct area monitoring and assume conservative occupancy of the waiting room. Another difference between public dose and occupational dose is that the dose limit itself is much lower for the public than for occupationally exposed individuals (

i.e.,

100 mrem/year vs. 5,000 mrem/year, respectively), and the public dose limit represents a very low level of risk. Specifically, as described in Table 12-4 of the BEIR VII report, the average lifetime risk of dying from cancer is 20 percent, and a lifetime (

i.e.,

70 years) of

exposure at the public dose limit of 100 mrem/year would conservatively result in an addition of only 0.35 percent to that average lifetime risk. Importantly, the public dose limit is based on the risk of cancer mortality to a large population that is assumed to be exposed at the full limit for a lifetime. However, as just mentioned in the nuclear power plant effluent and medical waiting room examples, in practice, licensees calculate bounding doses to smaller subsets of the population and use the parameters in those calculations to control doses (

e.g.,

reducing effluents from power plants or installing shielding around medical equipment). This means that the actual dose to the average member of the public from NRC licensed activities is assuredly below the limit, and thus, that that individual faces an even smaller risk than the already small risk that is assumed by a lifetime of exposure at the limit.

Because of these inherent conservatisms, the NRC would explain in guidance that one acceptable way of managing dose below the public dose limit—which management would be required under the proposed new graded approach to dose management—is to perform cost-benefit analyses using the assumptions of NUREG-1530, or equivalent assumptions, for any doses to members of the public that are projected to be greater than or equal to 25 percent of the public dose limit (

i.e.,

25 mrem/year). In addition, this approach to managing public dose would also be acceptable because the existing precautions in 10 CFR part 20 (

e.g.,

waste disposal regulations in subpart K) or other regulations intended to limit public dose (

e.g.,

10 CFR 50.36a) are sufficient to manage doses to the public within the public dose limits as required by § 20.1101. Stated another way, the assumptions in the calculation of public dose and in the public dose limit itself, in combination with already-existing NRC requirements related to dose management, make it so that it is acceptable to comply with the proposed new graded approach to dose management by not analyzing projected public doses below 25 mrem/year and by performing a cost-benefit analysis for projected public doses greater than or equal to 25 mrem/year. This approach would essentially reestablish the original intent of the ALARA principle of minimizing dose below limits to the extent that doing so is reasonably achievable and would ensure that dose limits are not exceeded. Again, as with the implementation of the proposed new graded approach to dose management for occupational dose, whereas the NRC's proposed guidance provides one way by which a licensee can satisfy that requirement for public dose, licensees may propose other ways to satisfy the requirement.

Effluents

The NRC's regulations include requirements for maintaining control over the release of radioactive material to the environment during normal reactor operations. For example, under § 50.34a and § 50.36a, the NRC requires nuclear power plant licensees to include in their facilities measures to control radiological effluents to the environment—including via monitoring and control systems—and to have in their licenses technical specifications to control the release of effluents. For power reactors, Appendix I to 10 CFR part 50 provides numerical design objectives regarding effluents. These design objectives are translated into performance criteria that are reflected in plant-specific technical specifications. In these requirements, effluents are quantified using the calculated dose that a member of the public would receive when exposed to the effluents under limiting conditions,

i.e.,

the hypothetical maximally exposed individual who represents the maximum exposure regarding food consumption, occupancy, and other usage in the vicinity of the plant site.

A similar requirement regarding air emissions for licensees not subject to § 50.34a and § 50.36a is provided in § 20.1101(d). These requirements were added to the NRC's regulations to provide design objectives and constraints to ensure that radioactive effluents (and thus the resulting public doses) would be maintained consistent with the ALARA principle. Additionally, the NRC has used these types of regulations to meet environmental protection-related obligations under the Clean Air Act (CAA) and to demonstrate compliance with the environmental protection standards for nuclear power operations under 40 CFR part 190. In NUREG-0543, the NRC describes how a licensee would be in compliance with the dose-based requirement in 40 CFR part 190, if the licensee maintains effluents below the numerical criteria of Appendix I to 10 CFR part 50.

In the context of the CAA, the NRC has historically worked with the U.S. Environmental Protection Agency (EPA) to develop effluent standards that are sufficiently low to support EPA determinations and to ensure that NRC licensees are not subjected to redundant regulation from multiple agencies (see,

e.g.,

42 FR 2858, 54 FR 51654, and 61 FR 65120). As part of the development of the current air emissions constraint in § 20.1101(d), the NRC ensured that the value of that constraint would be such that the Administrator of the EPA could determine that the constraint provided “ample margin of safety,” as is required under Section 112(d)(9) of the CAA. This “ample margin” determination is explained in the proposed and final rules that promulgated the National Emissions Standards for Hazardous Pollutants (NESHAPs) for radionuclides (54 FR 9612 and 54 FR 51654, respectively). EPA supported its determination that the NRC's regulations would satisfy the “ample margin” statutory requirement with studies of air emissions from NRC and Agreement State licensees. In total, these studies considered air emissions from 412 facilities on an annualized basis. EPA found that air emissions from most facilities do not result in doses exceeding 1 mrem/year with a small percentage of facilities approaching, but none exceeding, 10 mrem/year.

As part of its response to E.O. 14300, the NRC reconsidered risk analyses that are based on the LNT model and the implementation of the ALARA principle, as described elsewhere in this proposed rule. As it pertains to doses to members of the public, the NRC maintains that there is reasonable assurance that public health and safety is adequately protected at all doses below the NRC's current regulatory dose limit of 100 mrem/year. Dose reduction below this limit in and of itself is not necessary for ensuring the public health and safety; instead, as clarified by this proposed rulemaking, dose reduction serves the purpose of ensuring that ample margin exists to the regulatory dose limit and thus ensures that the limit is not exceeded. Regarding the contribution of effluents to public dose, this margin to the dose limit is maintained by the requirements in the NRC's regulations that pertain to the monitoring and control of effluents and by licensees' actions to manage dose, which could include performing cost-benefit analyses to support decision making on additional measures for controlling doses below the dose limits.

Accordingly, the NRC is proposing revisions to radionuclide emissions standards in 10 CFR 50.34a, 10 CFR 50.36a, 10 CFR part 50 Appendix I, and 10 CFR 20.1101(d) because it has determined that they are excessively cautious and overly burdensome. Specifically, the NRC is proposing to increase its radionuclide emissions standards from the current regulatory constraint in 10 CFR 20.1101(d) of 10 mrem per year to 25 mrem per year. The

NRC's position is that this would remove excess conservatisms while continuing to provide an adequate basis to EPA that the NRC's regulatory framework provides “ample margin of safety to protect the public health” under section 112(d)(9) of the CAA. To illustrate, in its proposed NESHAP rule for radionuclides, the EPA characterized the maximum lifetime risk of fatal cancer from natural background radiation from all sources, including naturally occurring radon, as approximately 1x10

−2

, or 1 case per 100 people. Using a current, widely accepted, and likely conservative cancer risk coefficient of 5x10

−4

per rem (see NCRP 180, Section 4.1), an individual receiving a dose of 10 mrem per year, the current regulatory constraint in 10 CFR 20.1101(d), for 70 years would experience an excess fatal cancer risk of 3.5x10

−4

, or about 0.04 cases per 100 people. If the dose to that individual were raised to 25 mrem per year, the proposed new regulatory constraint, for 70 years, the individual would experience an excess fatal cancer risk of 8.7x10

−4

, or about 0.09 cases per 100 people. When compared to the baseline lifetime risk of fatal cancer of approximately 0.2 (

e.g.,

as provided in Table 12-4 of the BEIR VII report), or 20 cases per 100 people, the risks of these environmental levels of radiation exposure, at both 10 mrem per year and 25 mrem per year, are a small fraction and well below the 100 mrem per year public dose limit.

In addition to reconsidering its current radionuclide emissions standards through a risk perspective, the uncertainties associated with risk estimates based on extrapolations from high-dose and high-dose-rate data provide additional support for the NRC's position that its proposed increase to its radionuclide emissions standards would remove excess conservatisms while still providing reasonable assurance of adequate protection of the public health and safety and would also continue to support EPA's determination that the NRC's standards provide an ample margin of safety under the CAA. Adjustments in the slope of the dose response curve, such as is done with the DDREF, are helpful in the extrapolation of high-dose/high-dose-rate data to low doses; however, there is subjectivity and potential conservatism associated with this adjustment. Additionally, there is evidence for adaptive cellular response, which would mitigate the health effects of exposures at low doses, especially those resulting from effluents. The NRC determined that these uncertainties were undervalued in the establishment of the radionuclide emissions standards that the NRC currently uses.

The NRC's proposed approach to the regulation of effluents would involve allowing licensees to continue using the existing effluent constraints of 10 mrem per year or allowing licensees to use a new constraint of 25 mrem per year TEDE or TED, as applicable. Regardless of the constraint used by a licensee, if the licensee demonstrates that its effluents are below the 25 mrem per year level, it would only be required to collect and retain effluent data on an annual basis and in a format that can be inspected by the NRC. If a licensee releases effluents greater than or equal to the 25 mrem per year constraint, that licensee would be required to collect and retain effluent data and submit relevant reports to the NRC on an annual basis until levels are returned to below the 25 mrem per year constraint. Additionally, such a licensee would be required to evaluate and consider implementing cost-justified corrective actions to restore effluent levels to below the 25 mrem per year constraint. NRC guidance would provide that one acceptable method for performing this evaluation would be to use the dollar per person rem value from NUREG-1530. If a cost analysis demonstrates that corrective actions are not justified, the licensee could propose a new constraint that would support continued operations in a cost-justified manner, but this new constraint would be required to be below the public dose limit. A similar approach would be taken during the licensing of a new facility,

i.e.,

a constraint higher than the regulatory constraint, but lower than the public dose limit, could be proposed as needed to support operations in a cost-justified manner. These changes are being proposed to §§ 20.1101(d), 50.34a, and 50.36a and to appendix I to 10 CFR part 50. To avoid disruptions to existing licensees, the NRC is proposing these changes such that existing effluent programs will remain compliant with the NRC's requirements, as amended, and that licensees can adopt changes on a voluntary basis.

The NRC understands that its radionuclide emissions constraint relates to EPA's ample margin determination under section 112(d)(9) of the CAA. According to CAA section 112(d)(9), the EPA must consult with NRC prior to a new or revised ample margin determination. The NRC's proposed position is that the proposed change to its radionuclide emissions constraint could continue to provide an adequate basis to EPA for such a determination.

Additionally, the NRC is proposing to revise paragraph C of Section IV of Appendix I to 10 CFR part 50 to add “§ 52.110” to the applicability of the provisions in that paragraph. This is an editorial change to make paragraph C consistent with the applicability specified in the introductory paragraph of Section IV.

Planned Occupational Dose Limit Extension

In the NRC's current regulations, planned special exposures (PSEs) (see 10 CFR 20.1206) allow occupationally exposed individuals to receive doses in excess of the applicable limit to a maximum of twice the applicable limit in one year, provided that certain criteria are met (

e.g.,

documentation tracking lifetime dose and remaining bank of PSE-dose). There is a cap on PSE-dose of five times the applicable limit over the lifetime of an individual. To ensure compliance with this lifetime cap, a licensee must ascertain the lifetime exposure history of an individual prior to conducting a PSE of that individual. Additionally, a PSE is viewed as a tool to be used only during exceptional circumstances. As such, PSEs involve additional reporting and recordkeeping requirements when compared to routine occupational exposures. Since the NRC added the regulations allowing for PSEs in the 1991 revisions to 10 CFR part 20, PSEs have not been used by licensees, as demonstrated through a lack of reports having been submitted to the NRC per § 20.2204.

The NRC has determined that the administrative burden associated with PSEs (

e.g.,

determination of lifetime exposure histories and additional reporting requirements) combined with the characterization of a PSE as a tool to be used only in exceptional circumstances is not commensurate with the radiological risk involved with exposures at occupational levels. Additionally, the increased administrative burden associated with PSEs likely dissuades licensees from viewing PSEs as a viable option for occupational dose management. Given this background and to enable flexibility in the balancing of occupational exposure with operational needs, the NRC is proposing to codify in 10 CFR 20.1205 a new process for allowing workers to receive doses in excess of applicable annual limits: the planned occupational dose limit extension (DLE). This optional process would make available to licensees a method to manage a justified, pre-planned exceedance of annual occupational limits for workers, provided that an

adequate decision-making process is applied to support its use and that the overall dose is limited within specified multi-year average values and annual limits are limited to twice the applicable limit. Although the NRC is also maintaining the current PSE process in its regulations, the proposed new planned occupational DLE would be less burdensome for licensees to implement while still maintaining occupational doses, and thus the underlying risk, within acceptable values.

The proposed new planned occupational DLE would allow licensees to access, in the current year, occupational dose that was not given to a worker in previous years. Dose limits generally serve two purposes: (1) to avoid nonstochastic/deterministic effects, also called tissue effects, and (2) to manage stochastic risk to an acceptable level. Nonstochastic/deterministic effects, or tissue reactions, are effects that are only seen once a threshold is exceeded and their severity is dependent upon the dose received. Protraction of dose reduces the risk of nonstochastic/deterministic effects especially at doses below the threshold because the body is able to heal the biological damage resulting from the dose received. Stochastic effects are random in nature; they are not subject to a threshold and the severity of the health effect is independent of the dose received. Currently accepted models assume that for stochastic effects the likelihood/risk of an adverse health effect occurring increases proportionately with dose. Each of the NRC's occupational dose limits functions to limit the risk of adverse health effects associated with radiation exposure to levels that have been determined to be acceptable for routine occupational situations.

Occupationally exposed individuals rarely approach even small fractions of applicable dose limits (see NUREG-0713) because of licensees' existing dose management efforts, which are generally founded on ALARA practices. In general, the fact that the risk from radiation exposure has been made negligible because of these dose management efforts is a net benefit. However, it is likely that these measures have resulted from overly conservative decision-making. Additionally, some licensees use locally developed administrative limits to maintain margin to occupational dose limits. Occasionally, normally during maintenance periods, licensees may encounter the need for workers to be exposed to doses in excess of annual limits but still within the standards for protecting against the health effects of radiation exposure (

e.g.,

long-term averages with respect to lifetime doses). In these cases, in part to avoid the added burden of PSE use, licensees employ additional measures (

e.g.,

shielding) or use additional workers to spread out the dose so as to maintain individual doses below limits. However, these actions may increase the cost and the time associated with the work in a manner that is not commensurate with the risk associated with the dose.

To encourage more reasonable decision-making regarding doses at levels corresponding to occupational exposures, consistent with the original intent of the ALARA principle and the proposed graded approach to dose management, the NRC is proposing to add to its regulations the planned occupational DLE process to allow licensees to periodically exceed applicable dose limits for an individual worker provided that certain criteria are met. The NRC proposes to define the dose allowed for a planned occupational dose limit extension as the occupational exposure that was unused by the individual over the most recent 5-year period. For example, for the TEDE limit of § 20.1201(a)(1), this would mean the dose available is equal to the product of 5 years and 5 rem TEDE, totaling 25 rem TEDE, minus the actual annual TEDE received by the individual in the current year and the preceding 4 years. A similar approach can be used to determine the allowable dose for a planned occupation dose limit extension of the deterministic limits, with the exception of the lens dose limit. Licensees would be able to apply this allowable dose, or “retrospective dose,” up to a total dose of twice the applicable annual dose limit in the current year. Thus, the annual limit for the planned occupational dose limit extension would be consistent with the dose that is allowed through the planned special exposure, with the exception of lens dose.

The safety basis for the proposed new planned occupational dose limit extension process relies on the fact that annual dose limits are derived with the intent to limit total lifetime exposure to an individual worker and to preclude deterministic effects. However, because total lifetime exposure is not a practical value to measure, radiation protection standards prescribe annual stochastic limits that are essentially fractionated lifetime totals. Therefore, the annual stochastic limits in and of themselves should not be viewed as demarcations of safety or thresholds above which health effects are expected. Instead, they are regulatory tools to manage the long-term risks of exposure. As such, these limits can safely be exceeded to a certain extent in the short-term, provided that long-term doses continue to be controlled adequately. When an occupationally exposed individual receives an annual dose below the annual limit, that individual is experiencing a smaller risk than was originally assumed to be acceptable for a radiation worker in developing the annual dose limits. In general, this is a positive outcome, primarily because of the corresponding reduction in risk that is associated with reductions in dose inherent to the statistical nature of stochastic effects. However, this also means that there often exists unused retrospective dose that could be safely used, provided that an adequate decision-making process is applied to support its use and that the overall dose is limited within specified multi-year average values. Deterministic effects would not result from the planned occupational dose limit extension process because those effects are only seen when certain thresholds are exceeded, and the restrictions on the planned occupational dose limit extension process would maintain doses below those thresholds.

The proposed new planned occupational dose limit extension process, as described in § 20.1205, would allow a licensee to authorize an individual worker to receive a dose in excess of annual occupational dose limits provided that (1) the licensee does not authorize a dose that would cause the individual to receive twice the applicable annual dose limit in a year, and (2) sufficient retrospective dose is available to the individual. This process would also entail limitations and reporting and recordkeeping requirements. For example, approval of a planned occupational dose limit extension for an adult worker must be in writing before the exposure occurs; the individual must be informed of the purpose of the planned operation, estimated doses and their associated risks, and measures taken to manage doses; and the licensee must determine the occupational exposure of the individual during the current and preceding four years (see 10 CFR 20.1205). Furthermore, declared pregnant women and minors would not be allowed to participate in planned occupational dose limit extensions. Additionally, because of the uncertainty associated with the health risks of lens dose, as discussed previously in this document, the NRC has decided to exclude exceeding the annual lens dose limit from the proposed new planned

occupational dose limit extension process; however, licensees could still use the current PSE process, which will remain in the NRC's regulations (including the required lifetime dose determination), in situations that involve a need to exceed the annual lens dose limit. Finally, the requirement to implement a graded approach to dose management would also apply to the management of the doses received during planned occupational dose limit extensions such that unnecessary occupational exposure would be avoided and radiation protection practices would be employed commensurate with the risks involved.

Public Dose Limits

The NRC is not proposing to change its current public dose limit, which is 100 mrem per year. The NRC considered several recommendations to change the public dose limit. As described previously, the 2015 PRMs requested an increase in the public dose limit based, in part, on the assertion that radiation exposure is beneficial. Additionally, the Idaho National Laboratory—a U.S. National Laboratory dedicated to energy research and development—recently suggested in a public report (“Reevaluation of Radiation Protection Standards for Workers and the Public Based on Current Scientific Evidence,” INL/RPT-25-85463, Revision 0, July 2025) that the public dose limit be raised, in part, to increase public acceptance of radiation exposure.

The NRC regulates the civilian use of radioactive materials in a manner that provides reasonable assurance of adequate protection of the public health and safety. Although the current public dose limit is sufficient to provide reasonable assurance of adequate protection of the public health and safety, the NRC understands that it is a generic limit and, thus, may be overly conservative in certain, specific circumstances. The NRC also recognizes that a number of factors may weigh in favor of allowing a higher public dose limit on a case-by-case basis when such conservatisms are specifically identified and accounted for, including why such an allowance would remain protective of the public health and safety. As discussed previously, in response to E.O. 14300 section 5(b), the NRC reexamined its approach to radiation protection and recognizes that there are inherent limitations in the LNT model, particularly at low doses, that could be better addressed in the NRC's rules. One example is the decision in the NRC's 1991 rulemaking to disallow exceptions to the public dose limit for new applicants. Upon reexamination, such a limitation is not needed for reasonable assurance of adequate protection of public health and safety and is also inconsistent with the principles of the E.O.s discussed in this document concerning enabling the use of nuclear power, particularly in light of the declared energy emergency in E.O. 14156. Taken together, these factors weigh in favor of the NRC reconsidering whether exceptions to the generic public dose limit of 100 mrem per year may be allowed. Therefore, although it is not proposing to change its current public dose limit or define specific exceptions to that limit, the NRC is proposing revisions to the regulations in § 20.1301 that would allow a licensee or an applicant to request alternative public dose limits on a sufficiently supported, case-by-case basis.

First, in § 20.1301(b), the NRC is proposing a path to enable a licensee or applicant to request prior NRC authorization for a public dose limit in excess of 100 mrem per year for members of the public who have access to controlled areas. Such requests may be on a generic basis (

e.g.,

for a design). A controlled area, as defined in § 20.1003, is an area, outside of a restricted area but inside the site boundary, to which access can be limited by the licensee for any reason. The NRC's current regulations extend the public dose limit to all areas within the site boundary. However, this approach may be excessively restrictive if dose is appropriately managed in the controlled areas. This is because members of the public do not maintain a lifetime of continuous occupancy in spaces within the controlled area boundary of licensed facilities. Instead, members of the public typically access these spaces on a temporary basis for such non-occupational-exposure purposes as tours, awaiting for or accompanying those receiving medical treatments, or work activities separate from those of the facility like making deliveries to/from the facility. Further, it is reasonable to assume that the majority of these individuals will be adults and that the time of exposure of any children will be small when compared to the lifetime of exposure that is considered when determining acceptable risks for stochastic health effects.

Therefore, the NRC is proposing to amend its regulations to provide that, as long as a licensee or applicant establishes appropriate dose management measures (

e.g.,

signage, information briefings and area monitoring to ensure compliance with the proposed higher annual dose limit), a higher public dose limit within the controlled area may be approved on a case-by-case basis. The NRC's case-by-case review would consider such things as the likely cumulative exposure of a member of the public under the proposed new dose limit given the time that the member of the public is expected to be within the controlled area and the effectiveness of the proposed dose management measures.

Second, in § 20.1301(d), the NRC is proposing to remove references to ALARA, to remove the upper limit on the annual dose limit for a member of the public that may be requested (which is currently set at 500 mrem per year), and to specify the information that is required in an application by a licensee or applicant for prior NRC authorization, on a case-by-case basis, for a public dose limit in excess of 100 mrem per year. The regulation at § 20.1301(d) was originally intended to provide a process for facilities existing at the time of the regulatory changes implemented in 1991 that found it difficult to meet the then newly enacted public dose limit of 100 mrem per year (see 56 FR 23360). However, the NRC now proposes to clarify that any licensee or applicant can apply for a higher public dose limit by providing the information required by the regulation, which the NRC will review on a case-by-case basis. Specifically, such an application must: (1) demonstrate the need for and the expected duration of operations in excess of the public dose limit; (2) describe the licensee's program to assess and control dose within the proposed higher limit; and (3) provide a supporting basis for the proposed higher limit, including why it remains protective of the public health and safety. Such a request for a higher public dose limit for the unrestricted area would require a more detailed analysis than a request for a higher public dose limit for the controlled area because of the lack of control that a licensee can exert over the unrestricted area and the presumably larger population that could potentially be subject to the proposed higher doses. Because of the statistical nature of stochastic health effects, the larger the population that receives a given dose, the larger the potential health impact. Therefore, it is likely that the NRC would generally reserve approvals for higher public dose limits that are limited in duration and/or demonstrated to have limited population impacts.

In their applications, in order to demonstrate that the requested higher public dose limit remains protective of the public health and safety, licensees and applicants could apply the critical

group or representative person concepts described in ICRP Publication 101, and earlier ICRP references, to perform prospective dose assessments. Determinate or probabilistic assessments, or a combination of both, could be used to support the request. Habit data and physiological characteristics should be representative of the affected population and not overly conservative in terms of assumptions. Additionally, licensees and applicants may consider the use of dose constraints, additional environmental monitoring, and land use censuses as part of their programs to assess and control dose within the proposed higher dose limits.

In addition to the proposed changes to allow requests for NRC authorization, on a case-by-case basis, for higher public dose limits in the controlled area and in the unrestricted area, the NRC is proposing two other changes to the requirements at § 20.1301: (1) changes to the limits that apply to caregivers of patients who cannot be released, and (2) deletion of the short-term dose rate limit for external sources in the unrestricted area.

First, the NRC is proposing to allow higher doses to members of the public who visit and/or care for medical patients who cannot be released under the provisions of § 35.75. Limits that apply to patient release are contained in 10 CFR part 35. The NRC has long permitted a member of the public to receive up to 500 mrem at the Authorized User's (AU) discretion under § 20.1301(c). Additionally, the NRC has approved several exemptions to this regulation as described in Regulatory Issue Summary (RIS) 2006-18, “Requesting Exemption from the Public Dose Limits for Certain Caregivers of Hospital Patients.” These exemptions allowed a caregiver to receive up to 2 rem, by default, with the flexibility to increase that amount if it was too low for a particular case. Similar to these previously issued exemptions, the NRC proposes to revise § 20.1301(c) to include a 2-rem limit for a caregiver and a 500-mrem limit for a non-caregiver member of the public per administration regimen. These limits are independent of the patient release regulations in 10 CFR 35.75, and doses accrued by caregivers or non-caregiver members of the public from exposure to a patient prior to release do not contribute to the patient's release evaluation. The guidance in RIS 2006-18 and the exemption process remain available to licensees should they desire to pursue authorization, on a case-by-case basis, to exceed the proposed new 2-rem limit for caregivers.

Amending the regulations to allow caregivers to receive up to 2 rem without a licensee requesting and having approved an exemption increases licensee flexibility, reduces regulatory cost and burden, and enables licensees to provide more timely care to patients while maintaining the public health and safety. The justification for the higher limit to the caregiver (

i.e.,

2 rem instead of 100 mrem) is that it is beneficial, or possibly essential, to the wellbeing of the patient for caregivers to have access to the patient and may, therefore, be considered an element of the patient's medical treatment. Caregivers are usually members of the patient's family or someone close to the family or the patient. Caregivers receive no financial compensation for the comfort or support that they provide a patient and knowingly consent to being exposed above the public dose limit.

Additionally, the higher dose limit is temporary and would not significantly impact the caregiver's lifetime fatal cancer risk. Similarly, the justification for the higher limit to the non-caregiver (

i.e.,

500 mrem instead of 100 mrem) is that the higher dose limit is temporary and would not significantly impact the individual's lifetime fatal cancer risk. A non-caregiver being exposed in a situation relevant to § 20.1301(c) is likely also a family member or a friend of the patient, thus their access to the patient provides relief during medical treatment. In ICRP Publication 60—which provided the ICRP's first set of comprehensive recommendations after the recommended public dose limit was changed to its current value—the ICRP stated in paragraph 192 that, “Since the detriment is a function of the accumulation of dose over many years, it would be unduly restrictive to require the controls to be related rigidly to annual dose limits. Some flexibility in the limits is desirable.” Accordingly, with this proposed rulemaking the NRC is proposing to exercise this flexibility as it relates to patient care.

Second, the NRC is proposing to delete the short-term dose rate limit in the unrestricted area of 0.002 rem in any hour in § 20.1301(b) because it serves no safety purpose that is not already achieved by the public dose limit of 100 mrem per year. This is because a member of the public could receive the full 100 mrem annual public dose instantaneously and this fact in and of itself would have minimal safety impact. The actual concern in such a hypothetical case would be that a source that could provide such a high dose rate would most assuredly result in an exceedance of the annual public dose limit in a short period of time and it is that exceedance that would require appropriate corrective actions and not the exceedance of any rate limit in receiving the dose. Licensees can voluntarily include short-term dose rate limits within their radiation protection programs for the purposes of dose management or to facilitate investigations of abnormal conditions; however, these are not necessary in addition to the annual public dose limit for the protection of the public health and safety. Therefore, the NRC is proposing to delete § 20.1301(a)(2) and the provision in § 20.1302(b)(2)(ii) that references 2 mrem in an hour.

License Termination Criteria

The NRC is proposing to revise the license termination criteria in 10 CFR part 20 subpart E to make conforming changes based on the discontinuation of the use of ALARA terminology in the NRC's regulations and guidance. Specifically, the NRC is removing the terms “as low as reasonably achievable” and “ALARA” from subpart E and replacing them, as appropriate. As explained previously in this document, the NRC's regulations and guidance would continue to use justification and optimization analyses to satisfy the original intent of the ALARA principle of, in this instance, reducing residual radioactivity to levels where further reductions would not be justified for both unrestricted and restricted use. The NRC intends for licensees to continue providing a combination of qualitative and quantitative analyses consistent with the guidance in NUREG-1757, volume 2, appendix N to satisfy the requirement to justify such reductions in residual radioactivity.

Additionally, the NRC is proposing to include a reference to § 20.1406(c) to its radiological criteria for unrestricted use at § 20.1402 to emphasize that the reduction in residual radioactivity may be justified by actions already taken by the licensee to minimize contamination. For example, licensees may be able to take credit for performing dismantlement and remediation activities in a way that minimizes the introduction of contamination to the environment in the analysis to demonstrate that further reductions are not justified. The NRC's proposed reference to this requirement would provide additional flexibility in the justification analysis required to comply with the proposed radiological criteria for unrestricted and restricted use.

With respect to restricted use, under § 20.1403 and § 20.1404, the NRC is proposing to increase clarity for licensees to demonstrate compliance with the proposed requirement that

further reductions in residual radioactivity necessary to comply with the provisions of § 20.1402 would not be justified. Currently, licensees must demonstrate that such reductions either would result in net public, or environmental harm or are consistent with ALARA. The NRC is proposing to introduce significantly more clarity by updating the requirement to include an explicit option to provide a cost-benefit analysis.

Finally, the NRC is making the language in 10 CFR part 20 subpart E consistent by using the broader term “traffic accidents” throughout instead of sometimes using the narrower term “deaths from transportation accidents.” The term “traffic accidents” encompasses the term “deaths from transportation accidents.”

Respiratory Protection

The NRC is proposing to make changes to its respiratory protection regulations to enable more efficient authorizations of respiratory equipment and their use. Currently, licensees are required to obtain individual authorization from the NRC in order to: (1) use respiratory equipment that has not been authorized by the National Institute for Occupational Safety and Health (NIOSH), and (2) use assigned protection factors (APFs) in excess of those specified in 10 CFR part 20. Through this rulemaking, a licensee would be allowed instead to reference approvals that the NRC has already issued to other licensees to use non-NIOSH certified equipment and/or to exceed the APFs in 10 CFR part 20; provided that the conditions in the safety evaluations used by the NRC to justify such approvals are applicable to that licensee. Effectively, this would mean that the NRC would only have to review and approve the use of new equipment or APFs once, and subsequent licensees could avail themselves of those approvals to the extent that they apply in their cases. This change would facilitate the use of modern equipment while minimizing risk and administrative burden because regulatory experience has shown that these reviews have not significantly differed once a precedent is established. In cases where the conditions of prior approvals would not apply or where licensee use of the equipment would not be within the scope of what the NRC considered in its safety evaluation, the licensee would have to individually apply for authorization as the regulations currently require.

Doses Received by a Member of the Public Due to Byproduct Material Administered for Medical Purposes

The NRC is proposing changes to 10 CFR part 35 regarding the release of patients who have been administered byproduct material. The first proposed change would add to 10 CFR 35.2 the definitions of “caregiver” and “administration regimen.” The proposed definition of “caregiver” is an adult who provides the patient with support or comfort for non-commercial gains following administration of byproduct material. The proposed definition of “administration regimen” is the course of administrations of a given radiopharmaceutical or brachytherapy source as intended by the authorized user. The second proposed change would amend 10 CFR 35.75 to add a provision to allow a consenting caregiver, who has been educated on the risks of radiation exposure, to receive up to 5 rem (

i.e.,

the occupation dose limit of 10 CFR 20.1201) per patient administration regimen. The dose limit to the general public would remain at 0.5 rem; however, the rule would be revised to specify that this limit is per administration regimen instead of per release. The third proposed change would amend 10 CFR 35.2075 to remove the requirement to keep records of dose evaluations for individual releases that meet certain criteria. Instead, the proposed change would require licensees to develop, implement, and maintain a written procedure for ensuring that a member of the public is not likely to exceed the established limits. The licensee would be required to retain this procedure for the duration of the license. Additionally, the proposed change would remove the requirement to document each instance where instructions are given to a breastfeeding patient.

In 2002, the NRC adopted the current dose-based criteria used in 10 CFR 35.75. At that time, the patient release framework was developed to address brachytherapy implants and single administration therapies (

e.g.,

I-131 therapy for conditions of the thyroid). Also at that time, other applications of byproduct material use in medicine did not involve quantities that would warrant concern regarding the release of patients. The medical landscape has evolved substantially since the current 10 CFR 35.75 was put in place. Namely, radiopharmaceuticals are increasingly being administered over a series of administrations as a matter of protocol, instead of all at once. With the proposed changes to 10 CFR 35.75, the NRC intends to adapt its patient release framework to better address the evolving use of byproduct material in medicine. While the limit for dose received by an individual member of the public is 0.5 rem per patient administration regimen, the NRC is proposing to introduce flexibility through the identification of a caregiver, who is eligible to receive up to the occupational dose limit (

i.e.,

5 rem) per patient administration regimen. Individuals identified as caregivers (

e.g.,

spouses, parents) are likely to receive the most dose as a result of a given patient release due to high duration or close contact activities, such as co-sleeping. Other members of the public are unlikely to receive a dose on the same order of magnitude as these potential caregivers. This is reflected in DG-8061 (the proposed revision 2 to Regulatory Guide (RG) 8.39) by using an assumed occupancy factor of 0.25 at 1 meter for a general member of the public (also referred to as a bystander) and an assumed occupancy factor of 1 at 1 meter for a caregiver in the tables provided. RG 8.39 contains additional information regarding patient-specific calculations for added flexibility, including lower occupancies for both caregivers and other members of the public.

The NRC is also proposing to change the recordkeeping requirements for patient release outlined in 10 CFR 35.2075 to better align with common practice. Most patients are likely to fall into certain categories that a licensee has previously determined to be compliant with release in accordance with 10 CFR 35.75. It is unnecessarily burdensome for licensees to retain the bases of release for individual patients who are released in such a way. As such, the NRC is proposing to instead require licensees to develop, implement, and maintain a written procedure for releasing patients in accordance with 10 CFR 35.75. The NRC is also proposing to remove the requirement to individually document when a breastfeeding patient has been given instructions following administration of byproduct material. The procedures required by the proposed 10 CFR 35.75 should detail the process for ensuring compliance for all patients who have been administered byproduct material, including situations where licensees provide instructions to patients who are breastfeeding. This change is intended to alleviate the burden associated with prescriptive recordkeeping requirements and to instead focus on the need to maintain a robust patient release program that enables the treatment of

patients while protecting members of the public.

For patients who cannot be released under 10 CFR 35.75, the NRC is proposing to amend 10 CFR 20.1301 to incorporate into that rule flexibilities introduced in RIS 2006-18. The proposed changes to 10 CFR 20.1301(c) would permit licensees, without having to apply for an exemption, to allow a caregiver, newly defined in the proposed changes to 10 CFR part 35, to receive up to 2 rem while providing care to a patient who cannot be released under 10 CFR 35.75. Any receipt of dose in excess of 2 rem would still require an application for an exemption and case-by-case prior approval by the NRC.

In 2002, the NRC amended 10 CFR part 20 to allow some visitors of patients who cannot be released under 10 CFR 35.75 to receive up to 500 mrem. At that time, the NRC acknowledged that, because visitors are often family members or close friends of patients, there is a substantial benefit that outweighs the risk of additional exposure. However, as the medical use of byproduct material has changed, it has come to the NRC's attention that a limit of 500 mrem is insufficient and overly cautious for some situations. While RIS 2006-18 does not set a maximum dose for which a licensee may apply for an exemption, 2 rem is the established initial dose limit for the outlined exemption. The NRC has already deemed a limit of 2 rem adequately protective for situations where a caregiver is necessary while a patient is hospitalized, provided that the licensee justifies the use of the exemption. The proposed rule would therefore eliminate the need for licensees to apply for an exemption for caregiver doses up to 2 rem. For caregiver doses in excess of 2 rem, licensees may still refer to RIS 2006-18. Note that caregiver doses received prior to the patient's release do not contribute to the 5 rem allowed by 10 CFR 35.75 following release. Finally, the proposed update to 10 CFR 20.2107 would require licensees to retain a record of the justification for a caregiver's dose for three years following the exposure.

Industrial Radiography

The NRC is proposing to remove from 10 CFR part 34 the definition of the term “ALARA” in § 34.3 and the prescriptive list of the radiation safety officer (RSO) responsibilities in § 34.42(c), which includes the term “ALARA.” Removing this term is consistent with the other changes being made as part of this rulemaking and removing the RSO responsibilities is consistent with other similar descriptions of requirements for RSOs. Licensees would continue to be able to look to guidance in NUREG-1556, volume 2, for more detailed information regarding the responsibilities of an RSO for industrial radiography.

Uniform Waste Manifest Forms

The NRC is also proposing changes to 10 CFR part 20 appendix G to provide additional clarity and flexibility on how the information requested on the Uniform Waste Manifest forms (NRC Forms 540 and 540A, 541 and 541A, and 542 and 542A) could be provided. The proposed changes would clarify that the Manifest does not need to include these NRC forms themselves as long as the Manifest reflects the information requested on the applicable NRC forms. Other proposed changes would remove language specifying when NRC Form 540 must physically accompany a shipment and would instead reference Department of Transportation (DOT) regulations. This change would ensure that the NRC's regulations are consistent with the DOT's regulations, including potential future changes to the DOT's regulations. The remaining proposed changes would add clarity and correct minor grammatical errors.

Clarifying Changes to Appendix A to 10 CFR Part 40

The NRC is proposing a change to the introduction section of Appendix A to 10 CFR part 40. The purpose of this change would be to clarify that the use of the phrase “as low as is reasonably achievable” in Appendix A has the same meaning as in EPA's generally applicable standards in 40 CFR part 192, which is different than how NRC has traditionally used ALARA. In this context, the use of the phrase “as low as reasonably achievable” is focused on the technical practicability of corrective actions. The remaining proposed changes to Appendix A are consistent with the proposed changes to 10 CFR part 20 in that they would require licensees to manage dose within the applicable limits and would require that practicable dose reduction measures be taken. The proposed changes would remove any language that implies that further dose reduction is required. In this context, the phrase “as low as reasonably achievable” will remain in Appendix A, Criterion 5B(6) to conform to EPA's generally applicable standards in 40 CFR part 192.

Conforming Changes to 10 CFR Parts 50, 61, 71, and 72

This proposed rule would also include additional conforming changes to align with the removal of references to ALARA. This includes the removal of a reference to ALARA in 10 CFR 50.66 and in 10 CFR 71.78. Additionally, removals of references to ALARA are proposed in 10 CFR part 72, specifically in §§ 72.3, 72.24, 72.44, 72.104, and 72.126. The changes proposed to § 72.44(d)(3) are conforming changes to align with the proposed changes to effluent reporting requirements in 10 CFR 50.34a, which are discussed in the previous section entitled “Effluents.”

Finally, the NRC is proposing to revise the public dose limits in 10 CFR part 61 to make conforming changes based on the discontinuation of the use of ALARA terminology in the NRC's regulations and guidance. Specifically, the NRC is proposing to remove the terms “as low as reasonably achievable” and “ALARA” from subpart C, “Performance Objectives.”

Conforming Changes to 10 CFR Part 53

The changes proposed in this rulemaking necessitate conforming changes to the recently issued 10 CFR part 53. In general, these changes serve two purposes. First, they acknowledge that licensees may potentially use dosimetry systems that provide results in terms of total effective dose, as opposed to total effective dose equivalent. Second, they provide the additional flexibility that is being included in the proposed changes to the NRC's overall radiation protection regulatory framework based on the agency's reconsideration of its use of the LNT model and its application of the ALARA principle.

The regulations at § 53.210, § 53.425, and § 53.530 are proposed to be revised to add reference to total effective dose to the units for dose-based criteria. Additionally, footnote 1 to § 53.210 is proposed to be revised to delete “TEDE” as the designation of the type of effective dose is not central to the purpose of the footnote, rather the magnitude of the dose is. The requirements at § 53.850 are proposed to be revised to change “limiting” to “controlling” to be consistent with the intent of effluent monitoring and control measures. Additionally, § 53.850(b)(2) is proposed to be revised to remove reference to the “Annual Radiological Environmental Operating and Radioactive Effluent Release Reports,” in lieu of a more generalized requirement for an effluent program to retain records and develop reporting criteria. This change conforms to changes being proposed in this rulemaking for radiological effluent monitoring and control through revisions to § 50.34a, § 50.36a, and

Appendix I to 10 CFR part 50. Lastly, § 53.1645(a) is proposed to be revised to add a process that conforms to the framework being proposed in this rulemaking for the monitoring and control of radiological effluents.

Updates to Design Basis Accident Dose-Based Acceptance Criteria

The NRC has historically used dose-based acceptance criteria when evaluating certain aspects of licensee safety assessments associated with applications for new reactors (

e.g.,

§ 50.34(a)(1)). Some of these safety assessments end up forming part of the current licensing basis of the facility after the NRC issues its license. Specifically, some of the accidents that are analyzed in these safety assessments are used to set the design basis of plant equipment to ensure public health and safety. These accidents are known as “design basis accidents.” Once incorporated into the current licensing basis, the assumptions, methodology, and equipment (including structures, systems, and components) are controlled as required by licensing-related regulations (

e.g.,

§ 50.90, § 50.59). The NRC has established dose-based acceptance criteria that recognize that certain design basis accidents have a higher assumed frequency of occurrence than others. To maintain the balance provided by the risk triplet—whereby changes in likelihood of occurrence of an accident may be offset by changes in consequences in order to control the risk of an event—the NRC has historically assigned a lower dose-based criteria value (

i.e.,

lower consequence) for accidents that are more likely to occur. In NRC guidance documents (

e.g.,

Branch Technical Positions and the Standard Review Plan in NUREG-0800) this approach is evidenced through the use of “well within,” or “a small fraction of” terminology in reference to fractions of the dose-based acceptance criteria used to evaluate the consequences of the maximum hypothetical accident described in Footnote 3 of § 50.34.

Historically, the NRC has interpreted the term “well within” to mean 25 percent of the dose resulting from a maximum hypothetical accident (or 6.3 rem) and the term “small fraction of” to mean 10 percent of the dose resulting from a maximum hypothetical accident (or 2.5 rem). This approach is implemented in Table 7 in RG 1.183, Revision 1, “Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors,” dated October 2023 (ML23082A305), but the practice can be observed in other guidance, such as Branch Technical Positions and the Standard Review Plan in NUREG-0800.

With this rulemaking, the NRC is proposing to adopt a single, dose-based acceptance criterion of 10 rem TEDE for design basis accidents that currently use criteria derived from fractions of the maximum hypothetical accident criterion of 25 rem TEDE. With this change the NRC will stop using the “well within” and “small fraction of” qualitative designations and their corresponding numerical values and instead use 10 rem TEDE. This new, dose-based acceptance criterion would apply at locations that are evaluated for radiological consequences (

i.e.,

exclusion area boundary and low population zone). Regulatory experience indicates that significant applicant, licensee, and NRC staff resources are expended in evaluating the results of these analyses, to include assumptions and plant configurations that support conclusions that the dose criteria are met. Additionally, licensees may encounter situations where equipment that has been determined as being necessary to satisfy the existing dose-based criteria becomes inoperable, sometimes necessitating emergent licensing actions to continue plant operations. These outcomes are not consistent with the safety significance of conservatively calculated doses on the order of 2.5 rem and 6.3 rem resulting from analyses of postulated events that have a very low probability of occurrence. This regu

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