Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors

NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

RIN 3150-AF00

Primary Reactor Containment Leakage Testing for Water-Cooled

Power Reactors

AGENCY: Nuclear Regulatory Commission.

ACTION: Proposed rule.

-----------------------------------------------------------------------

SUMMARY: The Nuclear Regulatory Commission is proposing to amend its

regulations to provide a performance-based option for leakage rate

testing of containments of light-water-cooled nuclear power plants.

This option will be available for voluntary adoption by licensees, in

lieu of compliance with the current prescriptive requirements contained

in the current regulation. This action is aimed at improving the focus

of the regulations by eliminating prescriptive requirements that are

marginal to safety. The proposed rule would allow test intervals to be

based on system and component performance, and provide licensees

greater flexibility for cost-effective implementation methods of

regulatory safety objectives.

DATES: Submit comments by May 8, 1995. Comments received after this

date will be considered if it is practical to do so, but the Commission

is able to assure consideration only for comments received on or before

this date.

ADDRESSES: Send comments to: Secretary, U.S. Nuclear Regulatory

Commission, Washington, DC 20555. ATTN: Docketing and Service Branch.

Hand deliver comments to: 11555 Rockville Pike, Rockville,

Maryland, between 7:45 a.m. and 4:15 p.m. Federal workdays.

Comments may be submitted electronically, in either ASCII text or

Wordperfect format (version 5.1 or later), by calling the NRC

Electronic Bulletin Board on FedWorld. The bulletin board may be

accessed using a personal computer, a modem, and one of the commonly

available communications software packages, or directly via Internet.

Background documents on the rulemaking are also available for

downloading and viewing on the bulletin board.

If using a personal computer and modem, the NRC subsystem on

FedWorld can be accessed directly by dialing the toll free number: 1-

800-303-9672. Communication software parameters should be set as

follows: Parity to none, data bits to 8, and stop bits to 1 (N,8,1).

Using ANSI or VT-100 terminal emulation, the NRC rulemaking subsystems

can then be accessed by selecting the ``Rules Menu'' option from the

``NRC Main Menu.'' For further information about options available for

NRC at FedWorld consult the ``Help/Information Center'' from the ``NRC

Main Menu.'' Users will find the ``FedWorld Online User's Guides''

particularly helpful. Many NRC subsystems and databases also have a

``Help/Information Center'' option that is tailored to the particular

subsystem.

The NRC subsystem on FedWorld can also be accessed by a direct dial

phone number for the main FedWorld BBS: 703-321-8020; Telnet via

Internet: fedworld.gov (192.239.93.3); File Transfer Protocol (FTP) via

Internet: ftp.fedworld.gov (192.239.92.205); and World Wide Web using:

http:// [[Page 9635]] www.fedworld.gov (this is the Uniform Resource

Locator (URL)).

If using a method other than the toll free number to contact

FedWorld, then the NRC subsystem will be accessed from the main

FedWorld menu by selecting the ``F--Regulatory, Government

Administration and State Systems,'' then selecting ``A--Regulatory

Information Mall''. At that point, a menu will be displayed that has an

option ``A--U.S. Nuclear Regulatory Commission'' that will take you to

the NRC Online main menu. You can also go directly to the NRC Online

area by typing ``/go nrc'' at a FedWorld command line. If you access

NRC from FedWorld's main menu, then you may return to FedWorld by

selecting the ``Return to FedWorld'' option from the NRC Online Main

Menu. However, if you access NRC at FedWorld by using NRC's toll-free

number, then you will have full access to all NRC systems, but you will

not have access to the main FedWorld system. For more information on

NRC bulletin boards call Mr. Arthur Davis, Systems Integration and

Development Branch, U.S. Nuclear Regulatory Commission, Washington, DC

20555, telephone (301) 415-5780; e-mail AXD[email protected].

Examine comments received, the draft environmental assessment and

findings of no significant impact, and the draft regulatory analysis

at: The NRC Public Document Room, 2120 L Street NW. (Lower Level),

Washington, DC; the PDR's mailing address is Mail Stop LL-6,

Washington, DC 20555; phone (202) 634-3273; fax (202) 634-3343. Copies

of the documents may be obtained from the PDR for a fee. These

documents may also be viewed and downloaded electronically via the

Electronic Bulletin Board established by NRC for this rulemaking.

The NRC also requests public comment on Draft NUREG-1493,

``Performance-Based Containment Leak Test Program.'' A free single copy

of draft NUREG-1493 may be requested by written request to the U.S.

Nuclear Regulatory Commission, ATTN: Distribution Section, Room P1-37,

Washington, DC 20555; fax (301) 504-2260. Comments on draft NUREG-1493

may be submitted to: Chief, Rules Review and Directives Branch,

Division of Freedom of Information and Publication Services, Mail Stop

T-6D59, U.S. Nuclear Regulatory Commission, Washington, DC 20555. Hand

deliver comments on draft NUREG-1493 to 11545 Rockville Pike, Maryland

between 7:45 a.m. and 4:15 p.m. on Federal workdays. Comments on draft

NUREG-1493 may be submitted electronically as indicated above under the

ADDRESSES heading.

FOR FURTHER INFORMATION CONTACT: Dr. Moni Dey, Office of Nuclear

Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC

20555, telephone (301) 415-6443, e-mail [email protected]

SUPPLEMENTARY INFORMATION:

Background

The NRC is proposing to amend 10 CFR part 50, appendix J in an

effort to relax and allow alternatives to those requirements that are

prescriptive and marginal to safety and yet impose a significant

regulatory burden on licensees. NRC reactor licensees are required

currently to conduct periodic primary reactor containment leakage

testing in accordance with 10 CFR part 50, appendix J, ``Primary

Reactor Containment Leakage Testing for Water-Cooled Power Reactors.''

Appendix J is currently prescriptive in that it specifies leak test

frequencies, pretest requirements, test methods, and reporting

requirements.

NRC's Marginal to Safety/Regulatory Improvement Program

In 1984, the NRC staff initiated a program to make regulatory

requirements more efficient by eliminating those with marginal impact

on safety. The NRC's initiative to eliminate requirements marginal to

safety recognizes both the dynamic nature of the regulatory process and

that the importance and safety contribution of some existing regulatory

requirements may not have been accurately predicted when adopted or may

have diminished with time. The availability of new technical

information and methods justify a review and modification of existing

requirements.

The NRC solicited comments from industry on specific regulatory

requirements and associated regulatory positions that needed

reevaluation. The Atomic Industrial Forum conducted a survey providing

most of industry's input, published for the NRC as NUREG/CR-43301,

``Review of Light Water Reactor Regulatory Requirements,'' Vol. 1,

April 1986. A list of 45 candidates for potential regulatory

modification were identified. The NRC's review of the list selected

Appendix J as one of seven areas requiring further analysis (NUREG/CR-

4330, Vols. 2 and 3, dated June 1986 and May 1987). The NRC also

conducted a survey of its staff concerning their expertise in a

particular area, experience in regulation, and knowledge of regulatory

requirements. The NRC staff survey identified 54 candidates, a number

of which were previously identified in the earlier survey. The NRC's

assessment of this list also selected appendix J as a potential

candidate for modification.

\1\Copies of NUREGs may be purchased from the Superintendent of

Documents, U.S. Government Printing Office, P.O. Box 37082,

Washington, DC 20013/7082. Copies are also available from the

National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161. A copy is available for inspection and/or

copying in the NRC Public Document Room, 2120 L Street, NW. (Lower

Level), Washington, DC.

---------------------------------------------------------------------------

The NRC published in the Federal Register, for comment, a proposed

revision to appendix J on October 29, 1986 (51 FR 39538) to update

acceptance criteria and test methods based on experience in applying

the existing requirements and advances in containment leak testing

methods, resolve interpretive questions, and reduce the number of

exemption requests. The October 29, 1986, proposed rule is being

withdrawn from further consideration and a more comprehensive proposed

rule that accounts for the latest technical information and regulatory

framework is being proposed.

The NRC's Marginal-to-Safety initiative is part of a broader NRC

initiative for regulatory improvement. Through its Program for

Regulatory Improvement, the NRC has institutionalized an ongoing effort

to eliminate requirements marginal to safety and to reduce regulatory

burden. The NRC staff's plan in SECY-94-090, dated March 31, 1994,

which satisfies the recent requirement for a periodic review of

existing regulations in Executive Order 12866 of September 30, 1993,

was approved by the Commission on May 18, 1994. The Regulatory

Improvement Program is aimed at the fundamental principle adopted by

the Commission that all regulatory burdens must be justified and that

its regulatory process must be efficient. In practice, this means the

elimination or modification of requirements where burdens are not

commensurate with their safety significance. The activities of the

Regulatory Improvement Program should result in enhanced regulatory

focus in areas that are more safety significant. As a result, an

overall net increase in safety is expected from the program.

The Regulatory Improvement Program will include, whenever feasible

and appropriate, the consideration of performance-oriented and risk-

based approaches. The program will review requirements or license

conditions that are identified as a significant burden on

[[Page 9636]] licensees. If review and analysis find that the

requirements are marginal to safety, they would be eliminated or

relaxed. By performance-oriented, the NRC means establishing regulatory

objectives without prescribing the methods or hardware necessary to

accomplish the objective, and allowing licensees the flexibility to

propose cost-effective methods for implementation. By risk-based, the

NRC means regulatory approaches that use probability risk analysis

(PRA) as the systematic framework for developing or modifying

requirements.

The present rulemaking is part of this overall effort and

initiative for eliminating requirements that are marginal to safety and

is guided by the policies, framework and criteria for the program.

The NRC published a notice in the Federal Register on February 4,

1992 (57 FR 4166), presenting its conclusion that appendix J was a

candidate whose requirements may be relaxed or eliminated based on

cost-benefit considerations. On the basis of NRC staff analyses of

public comments on the proposal, the Commission approved and announced

on November 24, 1992 (57 FR 55156) its plans to initiate rulemaking for

developing a performance-oriented and risk-based regulation for

containment testing requirements. On January 27, 1993, (58 FR 6196) the

NRC staff published a general framework for developing performance-

oriented and risk-based regulations and, at a public workshop on April

27 and 28, 1993, invited discussions of specific proposals for

modifying containment testing requirements. Industry and public

comments on the proposals, and other recommendations and innovative

ideas raised at the public workshop, were documented in the proceedings

of the workshop (NUREG/CP-0129, September 1993). Specifically, the NRC

concluded that the allowable containment leakage rate utilized in

containment testing may be increased and other Appendix J requirements

need not be as prescriptive as the current requirements. To increase

flexibility, the detailed and prescriptive technical requirements

contained in appendix J regulations could be improved and replaced with

performance-based requirements and supporting regulatory guides. The

regulatory guides would allow alternative approaches, although

compliance with current existing regulatory requirements would continue

to be acceptable. The performance-based requirements would reward

superior operating practices.

Performance-Based Regulatory Approach

In institutionalizing the Regulatory Improvement program and

adopting a performance-based regulatory approach, the NRC has

formulated the following framework for revisions to its regulations:

(1) The new performance-based regulation will be less prescriptive

and allow licensees flexibility to adopt cost-effective methods for

implementing the safety objectives of the original rule.

(2) The regulatory safety objectives will be derived, to the extent

feasible and practical, from risk considerations with appropriate

consideration of uncertainties, and will be consistent with the NRC's

Safety Goals.

(3) Detailed technical methods for measuring or judging the

acceptability of a licensee's performance relative to the regulatory

safety objectives will be, to the extent practical, provided in

industry standards and guidance documents which are endorsed in NRC

regulatory guides.

(4) The new regulation will be optional for current licensees so

that licensees can decide to remain in compliance with current

regulations.

(5) The regulation will be supported by necessary modifications to,

or development of, the full body of regulatory practice including, for

example, standard review plans, inspection procedures, guides, and

other regulatory documents.

(6) The new regulation will be formulated to provide incentives for

innovations leading to improvements in safety through better design,

construction, operating, or maintenance practices.

Current Appendix J Requirements

Appendix J to 10 CFR part 50, ``Primary Reactor Containment Leakage

Testing for Water-Cooled Power Reactors,'' became effective on March

16, 1973. The regulatory safety objective of reactor containment design

is stated in 10 CFR part 50, appendix A, ``General Design Criteria for

Nuclear Power Plants,'' Criterion No. 16, ``Containment Design.'' GDC

Criterion 16 mandates ``an essentially leak-tight barrier against the

uncontrolled release of radioactivity to the environment * * *'' for

postulated accidents. Appendix J to 10 CFR part 50 implements, in part,

General Design Criterion No. 16 and specifies containment leakage

testing requirements, including the types of tests required. For each

type of test required, Appendix J specifies how the tests should be

conducted, the frequency of testing, and reporting requirements.

Appendix J requires the following types of containment leak tests:

(1) Measurement of the containment integrated leak-rate (Type A

tests, often referred to as ILRTs).

(2) Measurement of the leak-rate across each pressure-containing or

leakage-limiting boundary for various primary reactor containment

penetrations (Type B tests).

(3) Measurement of the containment isolation valves leak-rates

(Type C tests).

Type B and C tests are referred to as local leak-rate tests

(LLRTs).

Leak-Tightness Requirements

Compliance with 10 CFR part 50, appendix J, requirements is

determined by comparing the measured containment leak-rate with the

maximum allowable leak rate. Maximum allowable leak-rates are

calculated in accordance with 10 CFR Part 100, ``Reactor Site

Criteria,'' and are incorporated into the technical specifications.

Typical allowable leak-rates are 0.1 percent of containment volume per

day for pressurized water reactors (PWRs) and one volume percent per

day for boiling water reactors (BWRs).

Test Frequency Requirements

Schedules for conducting containment leak-rate tests are specified

in appendix J for both preoperational and periodic tests. Periodic

leak-rate tests schedules are as follows:

Type A Tests. (1) After the preoperational leak-rate test, a set of

three Type A tests must be performed at approximately equal intervals

during each 10-year service period. The third test of each set must be

conducted when the plant is shutdown for the 10-year plant in-service

inspection.

(2) The performance of Type A tests must be limited to periods when

the plant facility is nonoperational and secured in the shutdown

condition under the administrative control and in accordance with the

safety procedures defined in the license.

(3) If any periodic Type A test fails to meet the applicable

acceptance criteria, the test schedule applicable to subsequent Type A

tests will be reviewed and approved by the Commission. If two

consecutive periodic Type A tests fail to meet the applicable

acceptance criteria, a Type A test must be performed at each plant

shutdown for refueling or approximately every 18 months, whichever

occurs first, until two consecutive Type A tests meet the acceptance

criteria, after which time the regular retest schedule may be resumed.

[[Page 9637]]

Type B Tests. (1) Except for airlocks, Type B tests must be

performed during reactor shutdown for refueling, or other convenient

intervals, but in no case at intervals greater than 2 years. If opened

following a Type A or B test, containment penetrations subject to Type

B testing must be tested prior to returning the reactor to an operating

mode requiring containment integrity. For primary reactor containment

penetrations employing a continuous leakage monitoring system, Type B

tests, except for tests of airlocks, may be performed every other

reactor shutdown for refueling but in no case at intervals greater than

3 years.

(2) Airlocks must be tested prior to initial fuel loading and at 6-

month intervals thereafter. Airlocks opened during periods when

containment integrity is not required by the plant's technical

specifications must be tested at the end of such periods. Airlocks

opened during periods when containment integrity is required by the

plant's technical specifications must be tested within 3 days after

being opened. For airlock doors opened more frequently than once every

3 days, the airlock must be tested at least once every 3 days during

the period of frequent openings. For airlock doors having testable

seals, testing the seals fulfills the 3-day test requirement. Airlock

door seal testing must not be substituted for the 6-month test of the

entire airlock at not less than Pa, the calculated peak

containment pressure related to the design basis accident.

Type C Tests. Type C tests must be performed during each reactor

shutdown for refueling but in no case at intervals greater than 2

years.

There have been two amendments to this appendix since 1973. The

first amendment published September 22, 1980 (45 FR 62789), modified

the Type B penetration test requirements to conform to what had become

accepted practice through the granting of exemptions. The second

amendment published November 15, 1988 (53 FR 45890) incorporated the

Mass Point statistical analysis technique as a permissible alternative

to the Total Time and Point-to-Point techniques specified in appendix

J.

European Experience

A combination of Type A tests and an on-line monitoring (OLM)

capability is being actively pursued in Europe, notably in France and

Belgium, and is currently being considered in Sweden. OLM is used to

identify a ``normal'' containment pressurization pattern and to detect

deviations from that pattern. The Belgians conduct a leak test using

OLM during reactor operation after each cold shutdown longer than 15

days with the objective of detecting gross leaks. The objective of the

Belgian approach to Type A testing is to reduce the frequency and

duration of the tests. The Type A test is conducted at a containment

pressure (Pt) not less than half of the peak pressure (0.5

Pa). It is performed once every 10 years.

In France, containment leaktightness is being continuously

monitored during reactor operation in all of the French PWR plants

using the SEXTEN system. It is also being evaluated by the Swedes for

their PWR units. Leaks may be detected during the positive or negative

pressure periods in the containment by evaluating the air mass balance

in the containment. Type A tests are conducted at containment peak

pressure (loss-of-coolant accident pressure) before initial plant

startup, during the first refueling, and thereafter every 10 years

unless a degradation in containment leak-tightness is detected. In that

case, tests are conducted more frequently.

Further details of European approaches to containment testing is

provided in Draft NUREG-1493.

Advance Notices for Rulemaking and Public Comments

Over time, it has become apparent that variations in plant design

and operation frequently make it difficult to meet some of the

requirements contained in appendix J because of its prescriptive

nature. Economic and occupational exposure costs are directly related

to the frequency of containment testing. Containment integrated leak

rate tests (Type A) preclude any other reactor maintenance activities

and thus are on the critical path for return to service from reactor

outages. In addition to the costs of the tests, integrated leak tests

impose the added burden of the cost of replacement power. Containment

penetration leak tests (Type B and C) can be conducted during reactor

shutdowns in parallel with other activities and thus tend to be less

costly; however, the large number of penetrations impose a significant

burden on the utilities. Additionally, risk assessments performed to

date indicate that the allowable leak rate from containments can be

increased, and that control of containment leakage at the current low

rates is not as risk significant as previously assumed.2 3

\2\Severe Accident Risks: An assessment for five U.S. Nuclear

Power Plants, Final Summary Report.'' NUREG-1150, December 1990.

Copies of NUREGs may be purchased from the Superintendent of

Documents, U.S. Government Printing Office, P.O. Box 37082,

Washington, DC 20013/7082. Copies are also available from the

National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161. A copy is available for inspection and/or

copying in the NRC Public Document Room, 2120 L Street, NW. (Lower

Level), Washington, DC.

\3\Performance-Based Containment Leak Test Program,'' Draft

NUREG-1493, January 1995. A free single copy of draft-1493 may be

requested by those considering public comment by writing to the U.

S. Nuclear Regulatory Commission, ATTN: Distribution Section, Room

P1-37, Washington, DC 20555. A copy is also available for inspection

and/or copying in the NRC Public Document Room, 2120 L Street, NW.

(Lower Level), Washington, DC 20555.

---------------------------------------------------------------------------

Initial NRC Proposal

In August of 1992, the Commission initiated a rulemaking to modify

appendix J to make it less prescriptive and more performance-oriented.

The Commission also initiated a plan to relax the allowable containment

leak-rate utilized to define performance standards for containment

tests. In the Federal Register published on January 27, 1993 (58 FR

6196), the NRC indicated the following potential modifications to

appendix J of 10 CFR part 50 would be considered:

(1) Increase allowable containment leak-rates based on Safety Goals

and PRA technology (i.e., define a new performance standard).

(2) Modify appendix J to be a performance-based regulation:

A Limit the revised rule to a new regulatory objective: In order

to ensure the availability of the containment during postulated

accidents, licensees should either:

(i) Test overall containment leakage at intervals not longer than

every 10 years, and test pressure-containing or leakage-limiting

boundaries and containment isolation valves on an interval based on the

performance history of the equipment; or

(ii) Provide on-line (i.e., continuous) monitoring of containment

isolation status.

B Remove prescriptive requirements from appendix J and preserve

useful portions as guidance in a NRC regulatory guide.

C Endorse industry standards on:

(i) Guidance for calculating plant-specific allowable leak-rates

based on new NRC performance standard;

(ii) Guidance on the conduct of containment tests; and

(iii) Guidance for on-line monitoring of containment isolation

status. [[Page 9638]]

D Continue to accept compliance with the current detailed

requirements in appendix J (i.e., licensees presently in compliance

with Appendix J will not need to do anything if they do not wish to

change their practice).

A public workshop on the subject was held by the NRC on April 27

and 28, 1993.4

\4\``Workshop on Program for Elimination of Requirements

Marginal to Safety.'' NUREG/CP-0129, September 1994.

---------------------------------------------------------------------------

Public Comments and Issues

Listed below are the categories of relevant issues identified by

the public, the nuclear industry, and the NRC at the public workshop

and in response to earlier solicitations for comments on this

rulemaking, and a summary of interests expressed. Summaries of

individual comments earlier solicitations were published on November

1992 (57 FR 55156). The comments at the public workshop are documented

in NUREG/CP-0129, September 1993. The comments are available for

inspection in the NRC Public Document Room.

1. Is there a continuing need for this regulation?

Most commenters agree that there is a continuing need for a

regulation on containment leak testing. While some commenters believe

the regulation should be tightened, most commenters believe appendix J

requirements should be relaxed. Industry representatives presented a

wealth of data on the cost and benefits of containment leak testing.

2. Should the NRC replace appendix J to 10 CFR part 50, ``Primary

Reactor Containment Leak Testing for Water-Cooled Power Reactors,''

with a non-prescriptive, performance-based rule?

One commenter believed that using conservatism that may far exceed

performance-based regulations is in the public's interest. Some

misallocation of resources does exist that could be corrected, although

there may be varying opinions concerning where they are. One commenter

believed that, from a public perception viewpoint, there would be

dissatisfaction with changing to performance-based regulation. It

appears to represent a streamlining or deregulation of standards.

Another view held that because there is no consistent regulatory basis,

there are inconsistencies in regulation. Performance-based regulations

would get rid of these inconsistencies. A move to performance-based

regulations would uncover marginal requirements. Performance-based

requirements would depend on the functional importance of a component

and might include deterministic performance standards for components. A

component that did not meet the performance standard would be rejected.

Another view was that the industry can use increased knowledge about

reactors and regulations within the existing technology to improve the

regulations and reduce risk, without relying on risk assessments. This

approach might result in earlier benefits. Industry generally

encouraged the NRC to proceed with its initiative to decrease the

prescriptiveness of its regulations and adopt more performance-based

approaches.

3. Should the NRC increase allowable containment leakage rates?

Some commenters believe that the existing appendix J requirements

for allowable leakage should not be relaxed and, based on their

interpretation of NUREG/CR-5747, ``Estimate of Radionuclide Releases

Characteristics into Containment Under Severe Accident Conditions,''

suggests that more stringent leakage limits, not relaxation of these

requirements, is appropriate. Because the current leakage rates

specified in plant technical specifications are based on relatively

conservative assumptions, the majority of commenters believe that a

more realistic representation of loss-of-coolant accidents should be

used to calculate dose to the public. These commenters believe that

more realistic accident scenarios would support a relaxation in the

containment leak-rate.

4. Should the NRC decrease Type A, B, and C test frequencies?

While some commenters had opinions on proper test frequencies, and

most believed that test frequencies could be relaxed, overall, the

technical community believed that examination of the technical data and

the objectives of the test should be used to determine the appropriate

test frequency. One commenter believed that both increased and

decreased frequencies might be appropriate. For example, tests might be

increased in frequency for valves that play a risk-significant role,

and test interval or allowable leak-rate could be increased for less

important components.

5. Can the new rule and its implementation yield an equivalent

level of, or only have a marginal impact on, safety?

Most commenters believe that a move to performance-based

regulations would uncover marginal requirements. Some believe that by

conserving resources in areas where safety is not a significant issue,

more resources can be devoted to more risk-significant areas with a net

increase in the overall safety margin.

6. Can the regulatory/safety objective (qualitative or

quantitative) be established in an objective manner to allow a common

understanding between licensees and the NRC on how the performance or

results will be measured or judged?

Several commenters believe that the regulatory process should

integrate deterministic, risk-based, and performance-based regulation

and allow for case-specific evaluation, with a goal of protecting the

health and safety of the public and at the same time minimizing the

cost to the licensee. Others believe that the opinions of public

interest groups should also be sought in deriving safety goals/

objectives. Overall, no comments were presented that would suggest that

a common understanding could not be achieved on goals and performance

measurements.

7. Can the regulation and implementation documents be developed in

such a manner that they can be objectively and consistently inspected

and enforced against?

Several commenters believe that the regulations should be

performance-based and the associated guidance documents should be

prescriptive so that only the guidance documents not the regulations

will need to be changed as more information is gained on compliance

issues. Many commenters believe that PRAs should not be the sole basis

for regulatory decisions due to the uncertainty in their results;

however, if the results indicate that a particular requirement has a

contribution to risk significantly below the Safety Goal thresholds,

the PRA information should be considered sufficient to justify

elimination of the requirement as marginal to safety.

Proposed Revision

Based on several advance notices for rulemaking and significant

public comment and discussion, risks and costs evaluated, and

consideration of which modifications are feasible and practical at this

time, the NRC proposes two phases for modifications of requirements to

containment leakage testing. The first phase, for which modifications

are proposed in this notice, will allow leak-rate testing intervals to

be based on the performance of the containment system structures and

components. The second phase will further examine the needed

requirements of the containment function (i.e. structural and leak-

tight integrity of containment system structures and components, and

prevention of inadvertent bypass), and include consideration of the

potential of on-line monitoring of containment [[Page 9639]] integrity

to verify certain functions. Solicitation of public comments to guide

this future work is included later in this notice.

The rule proposed in this notice would apply to all NRC licensees

who operate light water power reactors. The proposed rule would allow

licensees the option of continuing to comply with the current appendix

J or to adopt the new performance-based standards.

The NRC's analyses are based upon the insight gained through the

use of probability risk assessment techniques and the significant data

base of practical, hands-on operating experience gained since appendix

J was promulgated in 1973. This operating experience provides hard

evidence of the activities necessary to conduct appendix J testing, and

the costs of those activities both in monetary terms and occupational

radiation exposure.

The results of the present effort documented in draft NUREG-1493,

which are based on NUREG-1150, confirm previous observations of

insensitivity of population risks from severe reactor accidents to

containment leak-rates.

The current appendix J requirements have achieved the regulatory

criteria of assuring an essentially leak-tight boundary between the

power reactor system and the external environment (GDC Criterion 16).

Costs associated with complying with current appendix J requirements

are estimated to be $165,000 for a complete battery of Type B/C tests

and $1,890,000 for Type A tests. Over the average reactor's remaining

lifetime of 20 years, the present value of all remaining leak testing

at a five percent discount rate is about $7 million per reactor.

Estimates of the remaining industry-wide costs of implementing current

appendix J requirements range from $720 to $1,080 million,

approximately 75 percent of which could be averted with a performance-

based rule.

The present study found that by allowing requirements with marginal

effect on safety, but which impose a significant cost on licensees, to

remain in effect is to essentially misallocate a portion of the NRC's

and the industry's resources on activities for which there is no

commensurate return in safety. The real cost then may be in a missed

opportunity to focus NRC and licensee efforts to areas where the return

in terms of added public safety is higher.

Specific alternatives for modifying the current appendix J were

identified by the public in response to the NRC's Federal Register

notice published on January 27, 1993 (58 FR 6196). Those whose

characteristics matched the NRC's established criteria for the marginal

to safety program were selected for further review.

Modifications of Initial Proposals

Allowable Leakage Rate

The NRC had initially planned to establish, by rulemaking, a risk-

based allowable leak-rate commensurate with its significance to total

public risk. Specific findings from draft NUREG-1493 on the allowable

leakage rate include:

1. Allowable leakage can be increased approximately two orders of

magnitude (100-200 fold) with marginal impact on population dose

estimates from reactor accidents.

2. Calculated mean population risks are several orders of magnitude

below the NRC's Safety Goals for all reactors considered, but the tail

of the distribution can approach Safety Goals.

3. Increases in the allowable leak-rate is estimated to have a

negligible impact on occupational exposure.

Relaxing the allowable leak-rate is estimated to reduce future

industry testing costs by $50 to $110 million, a ten percent decrease

in overall leak-rate testing costs.

A risk-based allowable leakage rate would be based on an

evaluation, using PRA, of the sensitivity and significance of

containment leakage to risk, and determining an appropriate containment

leakage limit commensurate with its significance to the risk to the

public and plant control room operators. However, this would entail a

major change in policy and restructuring of the current licensing basis

and a more complete understanding of the uncertainties associated with

the threat of severe accidents to the containment, and therefore, the

NRC plans to consider a modification of the performance standard

(allowable leakage level) in the second phase separate from

modifications of testing requirements. This modification will be part

of a broader effort to further examine the risk significance of various

attributes of containment performance, i.e. structural and leak-tight

integrity of containment system structures and components, and

inadvertent bypass.

On-Line Monitoring (OLM) Systems

Currently, there is no requirement for OLM systems which monitor

the containment to detect unintentional breaches of containment

integrity.

Studies discussed in draft NUREG-1493, ``Performance-Based

Containment Leak Test Program,'' find that, based on operating

experience, OLM would not significantly reduce the risk to the public

from nuclear plant operation and, thus, cannot be justified solely on

risk-based considerations. Specific findings include:

1. Continuous monitoring methods that exist appear technically

capable of detecting leaks in reactor containments within 1 day to

several weeks. OLM systems are in use or planned in several European

countries.

2. OLM systems are only capable of detecting leaks in systems that

are open to the containment atmosphere during normal operation

(approximately ten percent of the mechanical penetrations).

3. The technical and administrative objectives of OLM systems and

Type A tests are different.

4. OLM cannot be considered as a complete replacement for Type A

tests because it cannot challenge the structural and leak-tight

integrity of the containment system at elevated pressures.

5. Analysis of the history of operating experience indicates

limited need for, and benefit of, OLM in the U.S.

Although OLM cannot be justified solely based on risk

considerations, a plant already possessing such a system has greater

assurance of achieving certain attributes of containment integrity.

Therefore, OLM systems could contribute towards an overall leakage

monitoring scheme. Some capability for on-line monitoring already

exists as a byproduct of specific containment designs. For example,

licensees with inerted BWR containments, or subatmospheric PWR

containments, would readily detect gross leakages that develop during

normal operation.

Given that the application of on-line monitoring is specific to

containment design, and generic application cannot be justified solely

on risk considerations, the NRC does not propose a requirement for

OLMs. However, licensees which already have such a capability (e.g.

inerted BWR containments, and subatmospheric PWR containments) are

encouraged to propose plant-specific application of such a capability,

including credit for any added assurance for certain attributes of

containment integrity provided by such a system compared to other

testing methods. The NRC will reconsider the role of OLM in the second

phase of modifications in this area along with the allowable leakage

rate.

Proposed Modification of Type A, B, C Test Intervals

The NRC proposes at this time, for the first phase of

modifications, to define a new risk-based regulation by utilizing the

performance history of components [[Page 9640]] (containment,

penetrations, valves) as the means to justify an increase in the

testing interval for Type A, B, and C tests. The revised regulation

would require tests to be conducted on an interval based on the

performance of the containment structure, penetration or valves without

specifying the interval in the regulation. Currently, three Type A

tests are conducted in every 10 year period. Type B (except airlocks,

which are tested more frequently) and C tests are conducted on a

frequency not to exceed 2 years.

The NRC proposes to base the frequency of Type A tests (ILRTs) on

the historical performance of the overall containment system. Specific

findings documented in draft NUREG-1493 that justify the proposal

include:

1. The fraction of leakages detected only by ILRTs is small, on the

order of a few percent.

2. Reducing the frequency of ILRT testing from three per 10 years

to one per 10 years leads to a marginal increase in risk.

3. ILRTs also test the strength of the containment structure. No

alternative to ILRTs have been identified to provide assurance that the

containment structure will meet allowable leakage rates during design-

basis accidents.

4. At a frequency of one test per 10 years, industry-wide

occupational exposure would be reduced by 0.087 person-sievert (8.7

person-rem) per year.

Based on specific, detailed analyses of data from the North Anna

and Grand Gulf plants and data from twenty-two nuclear plants (see

draft NUREG-1493), performance-based alternatives to current LLRT

methods are feasible with marginal impact on risk. Specific findings

that justify the proposal include:

1. Type B and C tests detect a very large fraction, over 97 percent

of containment leakages.

2. Of the 97%, virtually all leakages are identified by LLRTs of

containment isolation valves (Type C tests).

3. Based on the detailed evaluation of the experience of a single

2-unit station, no correlation of failures with type of valve or plant

service could be found.

4. For the 20 years of remaining operations, changing the Type B/C

test frequency alone is estimated to reduce industry-wide occupational

exposure by 0.72 person-sievert (72 person-rem) per year. If 20-year

license extension is assumed, the estimate is 0.75 person-sievert (75

person-rem) per year.

Reducing the frequency of ILRTs will reduce future industry testing

costs by approximately $330 to $660 million if tests are conducted once

per 10 years versus the current three per ten years. These savings

represent about 65 percent of the remaining costs of current appendix J

requirements. Performance-based LLRT alternatives are estimated to

reduce future industry testing costs by $40 million to $55 million.

These savings represent about five percent of the total remaining costs

of appendix J testing.

Therefore, based on the risks and costs evaluated, and other

considerations discussed above, a performance-based appendix J which

encompasses the following principles which differ moderately from those

first described in the Federal Register (January 27, 1993 58 FR 6197)

is proposed:

General. (1) Make appendix J less prescriptive and more

performance- oriented; (2) Move details of appendix J tests to a

regulatory guide as guidance; (3) Endorse approved industry guideline

(NEI 94-01) on guidance on the conduct of containment tests in a

regulatory guide. The methods for testing are contained in an industry

standard (ANSI/ANS 56.8-1994) which is referenced in the NEI guideline;

(4) Allow voluntary adoption of the new regulation, i.e., current

detailed requirements in appendix J will continue to be acceptable for

compliance with the modified rule.

Leakage Limits. Acknowledge the less risk-significant nature of

allowable containment leakage (La) but pursue its modification as

a separate action.

Type A Test Interval. (1) Based on the limited value of integrated

leak-rate tests (ILRTs) in detecting significant leakages from

penetrations and isolation valves, establish the test interval based on

the performance of the containment system structure; (2) The

performance criterion of the test will continue to be the allowable

leakage rate (La); (3) The industry guideline allows extension of the

Type A test interval to once every 10 years based on satisfactory

performance of two previous tests; (4) In the regulatory guide, the NRC

has included an exception for the extension of the interval of the

general visual inspection of the containment system, and limited the

interval to three times every 10 years as is current practice.

Type B & C Test Interval. (1) Allow local leak-rate test (LLRTs)

intervals to be established based on the experience history of each

component; (2) The performance criterion for the tests will continue to

be the allowable leakage rate (La); (3) Specific performance criteria

and factors for establishing extended test intervals (up to 10 years

for Type B components, and 5 years for Type C components) are contained

in the regulatory guide and industry guideline. In the regulatory

guide, the NRC has included an exception to the extension of Type C

test intervals up to 10 years that is proposed in the NEI industry

guideline, and limited such extensions to 5-years.

Specific Areas for Public Comment

In its preliminary criteria for developing performance-based

regulations, the NRC identified three issues to be addressed by the

rulemaking process as a measure of the viability of the revised rule.

These issues have been addressed in the rulemaking package and the NRC

is seeking further public input on them.

1. Can the new rule and its implementation yield an equivalent

level of, or would it only have a marginal impact on, safety?

The present study analyzed risks to the population and to workers

from changes in appendix J requirements. The results of the present

analysis confirm that population risks from severe reactor accidents

are not sensitive to containment leak-rates. The calculated risks are

well below the Safety Goals for all of the reactors considered even at

assumed containment leak-rates 100-fold above current requirements. A

change in the allowable leak-rate is estimated to have a negligible

impact on occupational exposure. Results also show that relaxing the

frequency of Type A, B, and C tests leads to an increase in overall

reactor risk of approximately two percent. This increase is considered

to be marginal to safety. Due to limitations of available plant data,

the uncertainties of the risk impact of extending Type C test intervals

beyond sixty months needs to be addressed.

Costs associated with complying with current appendix J

requirements are estimated to be $165,000 for a complete battery of

Type B/C tests, and $1,890,000 for Type A tests. Over the average

remaining lifetime of 20 years, the present value of all remaining leak

testing is about $7 million per reactor at a five percent discount

rate. The estimates of remaining industry-wide costs to comply with the

requirements of the current appendix J are approximately $720 to $1,080

million at a five percent discount rate, over 75 percent of which could

be averted with a risk-based rule.

Based on the results of the present study, the NRC concludes that

its safety objective for containment integrity can be maintained while

at the same time reducing the burden on licensees. Thus, the new rule

and its implementation can yield an equivalent level of, or only have a

marginal impact on, safety. [[Page 9641]]

2. Can the regulatory/safety objective (qualitative or

quantitative) be established in an objective manner to allow a common

understanding between licensees and the NRC on how the performance or

results will be measured or judged?

Conformance to the new appendix J requirements will be measured by

the adequacy of the methods for establishing the frequency of Type A, B

and C testing. It is a fundamental principle of this rulemaking that

changes to existing leak-test requirements be based objectively upon

the performance history of components as analyzed by established

methods.

To assist in the common understanding of new methods of

establishing Type A, B and C test frequencies between the NRC and power

reactor licensees, the NRC has had ongoing discussions with licensees.

These discussions included participation in workshops designed to

elicit a common understanding. From these efforts, the NRC is proposing

to endorse a guidance document from industry which specifies acceptable

methods for achieving compliance with Appendix J.

Further, the NRC proposes to require that plant technical

specifications provide a general reference to the regulatory guide or

other implementation document to ensure the prior review and approval

by the NRC of licensee deviations from approved methods. This will help

maintain a common understanding in the implementation of the

performance-based rule, and ensure adequate basis for licensee

deviations.

The NRC expects that its activities to date, the review and

endorsement of a industry guideline in a regulatory guide, and the

general reference of the regulatory guide in plant technical

specifications, will establish regulatory safety objectives in an

objective manner, and provide a common understanding on the measures of

compliance.

3. Can the regulation and implementation documents be developed in

such a manner that they can be objectively and consistently inspected

and enforced against?

A guidance document developed by industry and approved for use by

the NRC helps to ensure consistent interpretation and application of

compliance requirements. As experience is gained under the new rule,

adjustments may be reasonably anticipated to the industry's guidance

document which will be reviewed and approved by the NRC through the

regulatory guide revision process. The NRC's regulatory and inspection

personnel shall be trained in the interpretation and use of all

relevant implementation documents to assure consistent enforcement.

In addition to the above, the NRC solicits comments on the

following two issues.

4. Should the proposed revision be made even less prescriptive?

The proposed rule is less prescriptive than existing requirements

and provides licensees with greater flexibility in the implementation

of safety objectives established by NRC. This action is proposed based

on substantive technical analyses presented in draft NUREG-1493.

Regulatory positions were developed by the NRC through insights from

probabilistic risk analyses, operating data, and deterministic

engineering considerations. The NRC solicits public comment on whether

this revision should make the rule even less prescriptive than proposed

in this notice; and if so, how?

Specifically, comments are solicited on the potential alternative

of further relaxing the test frequency requirements for the Integrated

Leak Rate Tests (ILRT) by establishing a fixed ten-year interval based

on generic industry data, or perhaps eliminating the tests beyond the

first pre-operational test. Analyses of historical test data and risk

analyses presented in draft NUREG-1493 indicate that the ILRT interval

could be extended beyond the proposed ten-year interval, and perhaps

eliminated after the first pre-operational test with marginal impact on

safety. Leakages detected by an ILRT are rare and random, and not

generally related to previous performance at a plant. However, the NRC

considers that a ten-year testing interval, based on satisfactory

previous plant-specific performance, is appropriate at this time. It is

consistent with current industry practice for testing of pressure

vessels, and should detect the potential for aging mechanisms that

could affect containment leaktightness. Historical test data have not

yet shown evidence of such aging mechanisms but they might develop late

in life where little data exists. Comments are solicited on other

benefits provided by the ILRT, in addition to determining the leakage

rate, that would need to be addressed to justify further relaxations or

elimination of the test. NRC's current position is guided by the desire

to maintain some conservatism to address uncertainties and adopt an

evolutionary approach in the modification of its requirements. However,

the NRC does not wish to maintain undue conservatism in its

regulations, and therefore, will consider comments received to

determine the degree of prescriptiveness, and any further relaxation of

the ILRT requirements included in the final rule.

5. Should the proposed revisions be made mandatory?

The NRC is considering whether the proposed rule, which as

currently proposed would provide licensees with a non-mandatory

alternative to their existing appendix J containment leak testing

program, should instead be adopted as a mandatory requirement for all

licensees.

The proposed rule is drafted as a non-mandatory alternative to

current appendix J requirements because the Staff recognized that some

licensees may have technical programs which they may not wish to modify

at this time, even though a proposed modification would constitute a

``relaxation'' from current requirements or provide other regulatory or

economic benefit. For these reasons, the Commission earlier approved a

Staff policy whereby any proposed revisions to existing NRC

requirements developed by the Regulatory Improvement Program (See SECY-

94-090, ``Institutionalization of Continuing Program for Regulatory

Improvement,'' March 31, 1994) would not be mandatory, but would be

proposed as alternatives (options) to existing requirements which may

be voluntarily adopted by licensees. Given the history of difficulty

and low success rate for attempts to resolve new safety issues

simultaneously with improvements to regulatory efficiency, the

Commission also approved a Staff policy for separating regulatory

actions for new safety issues from those for improving regulatory

efficiency. Therefore, this proposed rule does not address any new

safety issues beyond the scope of the current appendix J requirements

and is not aimed at improving safety.

The NRC is interested in the public's view as to whether the

proposed rule should be made mandatory, in light of the overall long-

term reduction in regulatory burden on licensees and the marginal

impact on safety which would be entailed in the relaxation (see

previous discussion in ``Proposed Modification of Type A, B, C Test

Intervals). The NRC is interested in the public's views on using the

increase in regulatory efficiency as a potential rationale for making

the proposed rule mandatory for all licensees. The NRC also requests

public comment on the underlying policy discussed above that NRC

rulemakings which are not intended to increase safety, but are only

intended to increase regulatory efficiency and reduce the regulatory

burden imposed by the NRC's rules, [[Page 9642]] should be adopted as

alternatives to existing requirements which may be voluntarily adopted

by the regulated entity.

The NRC recognizes that if the proposed rule were made mandatory,

that several backfitting issues are raised. These backfitting concerns

are discussed in more detail in the next section on the ``Backfit

Rule.''

Backfit Rule

As discussed above, the Commission is considering whether the

proposed rule, which is currently drafted as providing licensees with a

non-mandatory alternative relaxing the requirements for and frequency

of containment leakage testing, should be adopted as a mandatory

requirement (that is, the requirements of the rule would be imposed on

all nuclear power plant licensees). If the alternative is made

mandatory, the Commission acknowledges the potential relevance of the

Backfit Rule. The Commission believes that the Backfit Rule was

intended to constrain the Commission's adoption of mandatory

relaxations of Commission requirements, if the mandated change imposed

costs upon the licensee and that such mandatory relaxations are

``backfits'' as defined in Sec. 50.109(a)(1). However, the Commission

believes that it has the authority and basis for ``waiving'' the

application of the Backfit Rule to the adoption of this rulemaking. The

Commission requests public comments on each of these points.

1. The Proposed Rule Constitutes a ``Backfit''

The current version of the Backfit Rule, 10 CFR 50.109, was adopted

in substantially its current form in 1985.5 50 FR 38097 (September

20, 1985). Based upon a review of the rulemaking record which led to

the final 1985 rule, the Commission's objective in adopting the Backfit

Rule was to prevent the imposition of new requirements, not otherwise

needed to assure adequate protection or compliance, which were of

marginal overall safety benefit or involved implementation costs which

were out of proportion to the safety benefits. The SOC explained that

under the new backfitting standard ``the Commission would not

ordinarily expect that safety improvements would be required as

backfits which result in an insignificant or small benefit to the

public health and safety or common defense and security, regardless of

the implementation costs'' (50 FR at 38102). Thus, the aim of the

Backfit Rule was to instill into the regulatory process the need for

disciplined analysis of proposed new requirements and regulatory

initiatives (See generally 50 FR at 38101-38102).

\5\The Backfit Rule was subsequently amended in 1988 (53 FR

20603, June 6, 1988) in response to a decision of the U.S. Court of

Appeals for the D.C. Circuit Union of Concerned Scientists et al. v.

U.S. Nuclear Regulatory Commission, 824 F.2d 103) which remanded the

1985 rule to the NRC because the rule failed to clearly indicate

that costs may not be a consideration in determining whether there

is adequate protection to the public health and safety.

---------------------------------------------------------------------------

The proposed revision relaxes and modifies existing requirements

where the Commission believes that the burdens are not commensurate

with their safety significance. Furthermore, the proposed rule does not

contain any new requirements to address new safety issues not addressed

in the original Appendix J rulemaking. However, if imposed as a

mandatory requirement the proposed rule would mandate changes in a

licensee's program for conducting containment leak rate tests, and

would impose short-term costs on the licensee in order to reduce the

long-term regulatory burden. However desirable such an imposition may

be over the long term, it would nonetheless constitute a ``backfit'' as

defined in Sec. 50.109(a)(1). However, the Commission requests public

comment on whether the definition of ``backfit'' in Sec. 50.109(a)(1)

was intended to encompass rulemakings of the type represented by this

proposed rule.

2. Waiving the Applicability of the Backfit Rule

The Commission adopted the Backfit Rule as a self-imposed

limitation on its rulemaking authority, and under the appropriate

circumstances the Commission may ``waive'' its applicability, subject

to the Administrative Procedure Act's requirement in rulemaking for

notice and opportunity for public comment. The Commission believes that

it is appropriate to ``waive'' the applicability of the Backfit Rule to

the proposed rule if its requirements were made mandatory. The purpose

of the rule is to relax and modify existing containment leak rate

testing requirements where burdens are not commensurate with their

safety significance. It does not contain any new requirements to

address new safety issues not addressed in the original appendix J

rulemaking. The proposed revision would relax existing marginal-to-

safety requirements in order to reduce regulatory burden on nuclear

power plant licensees and increase regulatory efficiency. This type of

rulemaking complements the objectives of the Backfit Rule by

eliminating requirements with little or no positive impact on safety,

but whose regulatory burden is substantial. Therefore, if the

Commission determines to impose the proposed rule's requirements, the

Commission proposes to ``waive'' this rule from the requirements of the

Backfit Rule.

The Commission requests public comment on the proposed rationale

for ``waiving'' the application of the Backfit Rule to this rulemaking.

Regulatory Guide; Issuance, Availability

A draft regulatory guide, temporarily identified by its task number

DG-1037, (on the same subject) ``Performance-Based Containment Leak-

Test Program'' is also being published for comment. The regulatory

guide endorses an industry standard which contains guidance on an

acceptable performance-based leak-test program, leakage rate test

methods, procedures, and analyses that may be used to implement these

requirements and criteria.

This draft guide is being issued to involve the public in the early

stages of the development of a regulatory position in this area. It has

not received complete staff review and does not represent an official

NRC staff position.

Public comments are being solicited on the draft guide. Comments

should be accompanied by supporting data. Specific comments are

solicited on whether the regulatory guide and the industry guideline it

endorses will result in a common understanding between licensees and

the NRC on how performance will be measured and judged, and can be

objectively inspected against. Written comments may be submitted to the

Rules Review and Directives Branch, Division of Freedom of Information

and Publications Services, Office of Administration, U.S. Nuclear

Regulatory Commission, Washington, DC 20555. Comments will be most

helpful if received by May 8, 1995. Comments on the draft regulatory

guide may be submitted electronically as indicated elsewhere under the

ADDRESSES heading.

Although a time limit is given for comments on these drafts,

comments and suggestions in connection with (1) items for inclusion in

guides currently being developed or (2) improvements in all published

guides are encouraged at any time.

Regulatory guides are available for inspection at the Commission's

Public Document Room, 2120 L Street NW., Washington, DC. Requests for

single copies of draft guides (which may be reproduced and are

available free to the extent of supply) or for placement on an

automatic distribution list for single copies of future draft guides in

specific [[Page 9643]] divisions should be made in writing to the

Office of Administration, Printing and Mail Services Section, U.S.

Nuclear Regulatory Commission, Washington, DC 20555-0001. Telephone

requests cannot be accommodated. Regulatory guides are not copyrighted,

and Commission approval is not required to reproduce them. The draft

regulatory guide may also be viewed and downloaded electronically via

the Electronic Bulletin Board established by NRC for this rulemaking.

Implementation

The proposed Option B to Appendix J specifies that the rule will

become effective 30 days after publication. At any time thereafter, a

licensee or applicant would notify the NRC of its desire to perform

containment leakage rate testing according to Option B. Accompanying

this notification, a licensee would submit proposed technical

specifications changes which would eliminate those technical

specifications which implement the current rule and propose a new

technical specification referencing the NRC regulatory guide or, if the

licensee desires, an alternative implementation guidance.

Implementation must await staff review and approval of the licensee's

proposal. The staff anticipates that a generic communication will be

issued which will provide the implementation procedure to all power

reactor licensees.

Solicitation of Comments for Future Revisions

As indicated earlier in this notice, the NRC plans a second phase

of modifications to requirements for containment leakage rate testing

to further adopt risk-based methods, and to broadly examine the type of

performance-based rule needed to ensure the adequacy of the containment

function. This will include increasing the allowable leakage rate based

on risk considerations, further examination of the risk significance of

various attributes of containment performance (structural and leaktight

integrity of containment structures and components, and inadvertent

bypass), and consideration of the potential of on-line monitoring of

containment integrity to address certain attributes. In order to guide

this future effort, the NRC has formulated the following questions and

solicits public comments on them:

1. Should NRC pursue a fundamental modification of its regulations

in this area by establishing an allowable leakage rate based on risk

analysis (as presented in draft NUREG-1493, Chapter 5), as compared to

the current practice of using deterministic design basis accidents and

dose guidelines contained in 10 CFR part 100; or should the NRC modify

the allowable leakage rate within the current licensing basis by

revising source terms and updating regulatory guides (R.G.s 1.3 and

1.4)6 for calculating doses to the public? What are the advantages

and disadvantages of the two approaches? What are some other

considerations than risk to public, e.g. plant control room

habitability, that might limit the allowable leakage rate?

\6\Copies may be purchased at current rates from the

Superintendent of Documents, U. S. Government Printing Office, Mail

Stop SSOP, Washington, DC 20402-9328 (telephone 202 512-2249 or 202

512-2171); or from the National Technical Information Service by

writing NTIS at Port Royal Road, Springfield, VA 22161.

---------------------------------------------------------------------------

2. If the allowable leakage rate is increased, could on-line

monitoring of containment integrity replace other current containment

tests? Could the results of the on-line monitoring be used to establish

a new performance basis for containment integrity involving less

stringent reporting requirements if there is high assurance there are

no large leakage paths in containment (> 1 in. diameter).

3. Are there any other regulatory approaches and technical methods

by which the NRC can adopt a complete performance and risk basis to its

regulations for containment leaktight integrity? What are some of the

attributes for performance, and what risk-based methods can be used to

analyze these attributes?

Finding of No Significant Environmental Impact: Availability

The Commission has determined under the National Environmental

Policy Act of 1969, as amended, and the Commission's regulations in

subpart A of 10 CFR part 51, that this rule, if adopted, would not be a

major Federal action significantly affecting the quality of the human

environment, and therefore an environmental impact statement is not

required. There will be no radiological environmental impact offsite,

and the occupational exposure onsite is expected to decrease by about

0.8 person rem per year of plant operation for plant personnel if

licensees adopt the performance-based testing scheme provided in the

revised regulation. Alternatives to issuing this revision of the

regulation were considered and found not acceptable. Single copies of

the environmental assessment and finding of no significant impact can

be obtained by submitting a written request to: Dr. Moni Dey, U.S.

Nuclear Regulatory Commission, Washington, DC 20555.

Paperwork Reduction Act Statement

This proposed rule amends information collection requirements that

are subject to the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et

seq.). This rule has been submitted to the Office of Management and

Budget for review and approval of the paperwork requirements.

Because the rule will relax existing information collection

requirements by providing an option to the existing requirements, the

public burden for this collection of information is expected to be

reduced by as much as 4583 hours per year, including the time required

for reviewing instructions, searching existing data sources, gathering

and maintaining the data needed and completing and reviewing the

collection of information. Send comments regarding the estimated burden

reduction or any other aspect of this collection of information to the

Information and Records Management Branch, T-6F33, U.S. Nuclear

Regulatory Commission, Washington, DC 20555-0001; and to the Desk

Officer, Office of Information and Regulatory Affairs, NEOB-10202,

(3150-0011), Office of Management and Budget, Washington, DC 20503.

Regulatory Analysis

The Commission has prepared a draft regulatory analysis on this

proposed regulation. The analysis examines the costs and benefits of

the alternatives considered by the Commission. The draft analysis is

available for inspection or copying for a fee in the NRC Public

Document Room, 2120 L Street NW (Lower Level), Washington, DC; the

PDR's mailing address is Mail Stop LL-6, Washington, DC 20555; phone

(202) 634-3273; fax (202) 634-3343.

The Commission requests public comment on the draft analysis.

Comments on the draft analysis may be submitted to the NRC as indicated

under the ADDRESSES heading.

Regulatory Flexibility Certification

In accordance with the Regulatory Flexibility Act of 1980, (5

U.S.C. 605(b)), the Commission certifies that this rule will not, if

promulgated, have a significant economic impact on a substantial number

of small entities. This proposed rule affects only the licensing and

operation of nuclear power plants. The companies that own these plants

do not fall within the scope of the definition of ``small entities''

set forth in the Regulatory Flexibility Act or the Small Business Size

Standards set [[Page 9644]] out in regulations issued by the Small

Business Administration in 13 CFR part 121.

Backfit Analysis

This proposed revision to a current regulation by the inclusion of

an option that may be voluntarily adopted by licensees, and which

relaxes current requirements, is not considered a backfit under 10 CFR

50.109(a). Therefore, a backfit analysis is not necessary.

List of Subjects in 10 CFR Part 50

Antitrust, Classified information, Criminal penalties, Fire

protection, Incorporation by reference, Intergovernmental relations,

Nuclear power plants and reactors, Radiation protection, Reactor siting

criteria, Reporting and recordkeeping requirements.

For the reasons set out in the preamble and under the authority of

the Atomic Energy Act of 1954, as amended, the Energy Reorganization

Act of 1974, as amended, and 5 U.S.C. 553, the NRC is proposing to

adopt the following amendments to 10 CFR part 50.

PART 50--DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION

FACILITIES

1. The authority citation for Part 50 is revised to read as

follows:

Authority: Secs. 102, 103, 104, 105, 161, 182, 183, 186, 189, 68

Stat. 936, 937, 938, 948, 953, 954, 955, 956, as amended, sec. 234,

83 Stat. 1244, as amended (42 U.S.C. 2132, 2133, 2134, 2135, 2201,

2232, 2233, 2236, 2239, 2282); secs. 201, as amended, 202, 206, 88

Stat. 1242, as amended, 1244 1246 (42 U.S.C. 5841, 5842, 5846).

Section 50.7 also issued under Pub. L. 95-601, sec. 10, 92 Stat.

2951, as amended by Pub. L. 102-486, sec. 2902, 106 Stat. 3123, (42

U.S.C. 5851). Sections 50.10 also issued under secs. 101, 185, 68

Stat. 936, 955, as amended (42 U.S.C. 2131, 2235); sec. 102, Pub. L.

91-190, 83 Stat. 853 (42 U.S.C. 4332). Sections 50.13, 50.54(dd),

and 50.103 also issued under sec. 108, 68 Stat. 939, as amended (42

U.S.C. 2138). Sections 50.23, 50.35, 50.55, and 50.56 also issued

under sec. 185, 68 Stat. 955 (42 U.S.C. 2235). Sections 50.33a,

50.55a and Appendix Q also issued under sec. 102, Pub. L. 91-190, 83

Stat. 853 (42 U.S.C. 4332). Sections 50.34 and 50.54 also issued

under sec. 204, 88 Stat. 1245 (42 U.S.C. 5844). Sections 50.58,

50.91, and 50.92 also issued under Pub. L. 97-415, 96 Stat. 2073 (42

U.S.C. 2239). Section 50.78 also issued under sec. 122, 68 Stat. 939

(42 U.S.C. 2152). Sections 50.80-50.81 also issued under sec. 184,

68 Stat. 954, as amended (42 U.S.C. 2234). Appendix F also issued

under sec. 187, 68 Stat. 955 (42 U.S.C. 2237).

2. Appendix J to 10 CFR Part 50 is amended by adding the following

language between the heading and the Table of Contents and adding the

language for Option B after Section V.B3.

Appendix J--Primary Reactor Containment Leakage Testing for Water-

Cooled Power Reactors.

This appendix includes two options, A and B, either of which can

be chosen for meeting the requirements of this appendix.

Options A--Prescriptive Requirements

* * * * *

Option B--Performance-Based Requirements

Table of Contents

I. Introduction.

II. Definitions.

III. Performance-based leakage test requirements.

A. Type A test.

B. Type B and C tests.

IV. Recordkeeping.

V. Implementation.

I. Introduction

One of the conditions required of all operating licenses for

light-water-cooled power reactors as specified in Sec. 50.54(o) is

that primary reactor containments meet the leakage rate test

requirements in either Option A or B of this appendix. These test

requirements ensure that (a) leakage through these containments or

systems and components penetrating these containments does not

exceed allowable leakage rates specified in the Technical

Specifications and (b) integrity of the containment structure is

maintained during its service life. Option B of this appendix

identifies the performance-based requirements and acceptance

criteria for preoperational and subsequent periodic leakage rate

testing.7

\7\Specific guidance concerning a performance-based leak test

program, acceptable leakage rate test methods, procedures, and

analyses that may be used to implement these requirements and

criteria are provided in draft Regulatory Guide DG-1037,

``Performance-Based Containment System Leakage Testing.''

---------------------------------------------------------------------------

II. Definitions

Acceptance criteria means the performance standards against

which test results are to be compared for establishing the

acceptability of the containment system as a leakage limiting

boundary.

Containment system means the principal barrier, after the

reactor coolant pressure boundary, to prevent the release of

quantities of radioactive material that would have a significant

radiological effect on the health of the public.

Overall integrated leakage rate means the total leakage rate

through all tested leakage paths, including containment welds,

valves, fittings, and components that penetrate the containment

system.

La (percent/24 hours) means the maximum allowable leakage rate

at pressure Pa as specified in the Technical Specifications.

Pa (p.s.i.g) means the calculated peak containment internal

pressure related to the design basis loss-of-coolant accident as

specified in the Technical Specifications.

III. Performance-Based Leakage Test Requirements

A. Type A Test

Type A tests to measure the containment system overall

integrated leakage rate must be conducted under conditions

representing design basis loss-of-coolant accident containment peak

pressure. A Type A test must be conducted (1) after the containment

system has been completed and is ready for operation and (2) at a

periodic interval based on the historical performance of the overall

containment system as a barrier to fission product releases to

reduce the risk from reactor accidents. A general visual inspection

of the accessible interior and exterior surfaces of the containment

system for structural deterioration which may affect the containment

leaktight integrity must be conducted prior to each test, and at a

periodic interval between tests based on the performance of the

containment system. The leakage rate must not exceed the allowable

leakage rate (La) with margin as specified in the Technical

Specifications. The test results must be compared with previous

results to examine the performance history of the overall

containment system to limit leakage.

B. Type B and C Tests

Type B pneumatic tests to detect and measure local leakage rates

across pressure retaining, leakage limiting boundaries, and Type C

pneumatic tests to measure containment isolation valve leakage

rates, must be conducted (a) prior to initial criticality, and (b)

periodically thereafter at intervals based on the safety

significance and historical performance of each boundary and

isolation valve to ensure the integrity of the overall containment

system as a barrier to fission product release to reduce the risk

from reactor accidents. The performance-based testing program must

contain performance goals and acceptance criteria, consideration of

factors that affect performance when establishing test intervals,

evaluations of performance of containment system components, and

comparison to previous test results to examine the performance

history of the overall containment system to limit leakage. The

tests must demonstrate that (1) the sum of the leakage rates at

accident pressure of Type B tests, and pathway leakage rates from

Type C tests, is less than the total allowable leakage rate (La)

specified in the Technical Specification with margin; and (2) the

performance goal for the reliability of the overall containment

system to limit leakage during reactor accidents is not exceeded.

IV. Recordkeeping

The results of the preoperational and periodic Type A, B, and C

tests must be documented to show that acceptance criteria for

leakage have been met. The comparison to previous results of the

performance of the overall containment system and of individual

components within it must be documented to show that the test

intervals established for the containment system and components

within it are adequate. These records must be available for

inspection at plant sites.

If any Type A, B, or C tests fail to meet their leakage rate

acceptance criteria as [[Page 9645]] defined in the plant Technical

Specifications those failures must be assessed for Emergency

Notification System reporting under Secs. 50.72(b)(1)(ii) and

50.72(b)(2)(i), and for a Licensee Event Report under

Secs. 50.73(a)(2)(ii).

V. Implementation

A. Applicability

The requirements in either or both Option B, III.A for Type A

tests, and Option B, III.B for Type B and C tests, may be adopted on

a voluntary basis by an operating nuclear power reactor licensee as

specified in Sec. 50.54 in substitution of the requirements for

those tests contained in Option A of this appendix. If the

requirements for tests in Option B, III.A or Option B, III.B are

implemented, the recordkeeping requirements in Option B, IV for

these tests must be substituted for the reporting requirements of

these tests contained in Option A of this appendix.

B. Effective Date

1. Specific exemptions to Option A of this appendix that have

been formally approved by the AEC or NRC, according to 10 CFR 50.12,

are still applicable to Option B of this appendix if necessary,

unless specifically revoked by the NRC.

2. This amendment to this appendix, by inclusion of an

additional option for meeting the requirements of the appendix, is

effective (30 days after the publication of the final rule). At any

time hereafter a licensee or applicant for an operating license can

adopt Option B, or parts thereof, as specified in Section V.A of

this appendix, by submitting a notification of its implementation

plan and request for revision to technical specifications to the

Director of the Office of Nuclear Reactor Regulation.

The regulatory guide or other implementation document used by a

licensee, or applicant for an operating license, to develop a

performance-based leakage testing program must be included, by

general reference, in the plant's technical specifications. The

detailed licensee programs must be available at the plant site for

inspection thereafter. The programs must contain justification,

including supporting analyses, if they deviate from methods approved

by the Commission and endorsed in a regulatory guide. The deviations

and their justifications must be described in the notification

provided by the licensee of its implementation plan and the

submittal for revision of plant technical specifications.

Dated at Rockville, MD, this 14th day of February, 1995.

For the Nuclear Regulatory Commission.

John C. Hoyle,

Acting Secretary of the Commission.

[FR Doc. 95-4167 Filed 2-17-95; 8:45 am]

BILLING CODE 7590-01-P