ML121030286

Safety Evaluation of NEI TR 94-01, Revision 3, Performance-based Option of 10 CFR Part 50, Appendix J

ML121030286
Person / Time
Site:	Nuclear Energy Institute
Issue date:	06/08/2012
From:	Bahadur S Division of Policy and Rulemaking
To:	Bradley B Nuclear Energy Institute
Stuchell S, NRR/DPR,301-415-1847
References
NEI 94-01, Rev 3
Download: ML121030286 (16)

Text

June 8, 2012 Mr. Biff Bradley, Director Risk Assessment Nuclear Generation Division Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington, DC 20006-3708

SUBJECT:

FINAL SAFETY EVALUATION OF NUCLEAR ENERGY INSTITUTE (NEI)

REPORT, 94-01, REVISION 3, INDUSTRY GUIDELINE FOR IMPLEMENTING PERFORMANCE-BASED OPTION OF 10 CFR PART 50, APPENDIX J (TAC NO. ME2164)

Dear Mr. Bradley:

By letter dated June 9, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML112920567), the NEI submitted for U.S. Nuclear Regulatory Commission (NRC) staff review and approval NEI TR 94-01, Revision 3, Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J. This letter transmits the Safety Evaluation (SE).

The NRC staff has found that NEI TR 94-01, Revision 3 is acceptable for referencing in licensing applications to the extent specified in the enclosed final SE. The SE defines the basis for acceptance of the TR. The staffs final SE of the NEI TR 94-01, Revision 3 report, includes two conditions. The TR describes an acceptable approach for implementing the optional performance-based requirements of Option B to 10 CFR Part 50, Appendix J, which includes provisions for extending Type C Local Leakage Rate Test intervals to up to 75 months. This method uses industry performance data, plant-specific performance data, and risk insights in determining the appropriate testing frequency.

Our acceptance applies only to material provided in the subject TR. We are not required to repeat our review of the acceptable material described in the TR during a licensing action referencing this TR. When the TR appears as a reference in license amendment requests or license renewal applications, our review will ensure that the material presented applies to the specific plant involved. License amendment requests or references to this TR that deviate from this TR will be subject to a plant-specific review in accordance with applicable review standards.

B. Bradley In accordance with the guidance provided on the NRC public website, we request that NEI publish an accepted version of this TR within three months of receipt of this letter. The accepted version shall incorporate the changes outlined in the SE, this letter, and the enclosed final SE after the title page. Also, it must contain historical review information, including NRC requests for additional information and your responses. The accepted version shall include a "-A" (designating accepted) following the TR identification symbol. If future changes to the NRC's regulatory requirements affect the acceptability of this TR, NEI and/or licensees referencing it will be expected to revise the TR appropriately, or justify its continued applicability for subsequent referencing.

Sincerely,

/RA/

Sher Bahadur, Deputy Director Division of Policy and Rulemaking Office of Nuclear Reactor Regulation Project No. 689

Enclosure:

Final SE

ML121030286; TAC No. ME2164; *via e-mail NRR-043 OFFICE DPR/PLPB/PM DPR/PLPB/LA DSS/SCVB/BC DPR/PLPB/BC DPR/DD NAME SStuchell DBaxley RDennig* JJolicoeur SBahadur DATE 4/12/2012 5/8/2012 6/4/2012 6/7/2012 6/8/2012 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION NUCLEAR ENERGY INSTITUTE TOPICAL REPORT 94-01, REVISION 3, INDUSTRY GUIDELINE FOR IMPLEMENTING PERFORMANCE-BASED OPTION OF 10 CFR PART 50, APPENDIX J NUCLEAR ENERGY INSTITUTE PROJECT NO. 689

1.0 INTRODUCTION

The objective of the topical report (TR) process is, in part, to add value by improving the efficiency of other licensing processes, for example, the process for reviewing license amendment requests from commercial operating reactor licensees. The purpose of the U.S.

Nuclear Regulatory Commission (NRC) TR program is to minimize industry and NRC time and effort by providing for a streamlined review and approval of a safety-related subject with subsequent referencing in licensing actions, rather than repeated reviews of the same subject.

A TR is a stand-alone report containing technical information about a nuclear power plant safety topic, which meets the criteria of a TR. A TR improves the efficiency of the licensing process by allowing the NRC staff to review a proposed methodology, design, operational requirements, or other safety-related subjects that will be used by multiple licensees, following approval, by referencing the approved TR. The TR provides the technical basis for a licensing action.

During the review of the Nuclear Energy Institutes (NEI) TR 94-01, Revision 3, the NRC staff found that, in general, the TR meets the objectives of a TR and reinforces previously established NRC regulations and guidelines as noted within this safety evaluation (SE). The NRC has evaluated this TR against the criteria of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, and has determined that it does not represent a backfit. Specifically, NRC staff technical positions outlined in this SE are consistent with the aforementioned regulations and established staff positions, while providing more detailed discussion concerning the methodology and data required supporting surveillance testing frequencies. This SE endorses staff positions previously established through licensing actions and interactions with industry.

1.1 Background In 1995, the NRC amended 10 CFR Part 50, Appendix J, Primary Reactor Containment Leakage Testing For Water-Cooled Power Reactors, to provide a performance-based Option B for the containment leakage testing requirements. Option B requires that test intervals for Type A, Type B, and Type C testing be determined by using a performance-based approach.

Performance-based test intervals are based on consideration of the operating history of the component and resulting risk from its failure. The use of the term performance-based in Appendix J to 10 CFR Part 50 refers to both the performance history necessary to extend test intervals as well as to the criteria necessary to meet the requirements of Option B.

Page of 13 Type A tests focus on verifying the leakage integrity of a passive containment structure. Type B and C testing focus on assuring that containment penetrations are essentially leak tight. These tests collectively satisfy the requirements of 10 CFR Part 50, Appendix J, Option B as stated in the Introduction section of Appendix J:

The purposes of the tests are to assure that (a) leakage through the primary reactor containment and systems and components penetrating primary containment shall not exceed allowable leakage rate values as specified in the technical specifications (TSs) or associated bases; and (b) periodic surveillance of reactor containment penetrations and isolation valves is performed so that proper maintenance and repairs are made during the service life of the containment, and systems and components penetrating primary containment.

NEI issued NEI 94-01 Revision 0, Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J, on July 26, 1995 (Reference 1). The guidance found in NEI 94-01, Revision 0, provides a performance-based approach for determining Types A, B, and C containment leakage rate surveillance testing frequencies. Per NEI 94-01, Revision 0, the maximum Type A testing shall be performed at a frequency of at least once per 10 years; intervals for Types B and C tests may be increased from 30 months up to a maximum of 120 months (except for containment airlocks).

Regulatory Guide (RG) 1.163, Performance-Based Containment Leak-Test Program, was issued in September 1995 (Reference 2), after 10 CFR Part 50, Appendix J was revised. RG 1.163 provides guidance on an acceptable performance-based leak-test program, leakage-rate test methods, procedures, and analyses that may be used to comply with the performance-based Option B in 10 CFR Part 50, Appendix J, and endorsed NEI 94-01, Revision 0 subject to certain regulatory positions, with one being:

Because of uncertainties in historical Type C component performance data, and because of the indeterminate time period of three refueling cycles and insufficient precision of programmatic controls described in Section 11.3.2 to address these uncertainties, the guidance provided in Section 11.3.2 for selecting extended test intervals greater than 60 months for Type C tested components is not presently endorsed by the NRC staff.

Option B, in concert with RG 1.163 and NEI TR 94-01, Revision 0, allows licensees with a satisfactory integrated leak rate testing (ILRT) performance history (i.e., two consecutive, successful Type A tests) to reduce the test frequency for the Type A containment ILRT from three tests in 10 years to one test in 10 years. This relaxation was based on an NRC risk assessment contained in NUREG-1493, Performance-Based Containment Leak-Test Program (Reference 3), and the Electric Power Research Institute (EPRI) document TR-104285, Risk Impact Assessment of Revised Containment Leak Rate Testing Intervals (Reference 4), both of which showed that the expected risk increase associated with extending the ILRT surveillance interval was very small.

In 2001, the NEI initiated a project to justify further reduction of the ILRT test frequency from one test in 10 years to one test in 20 years based on performance history and risk insights. In view of the time required to develop, approve, and promulgate generic guidance material, the

Page of 13 NEI tasked the EPRI to develop interim guidance to licensees for developing uniform risk assessments supporting one-time extensions of the ILRT surveillance interval to 15 years (i.e., a test frequency of one test in 15 years). The NEI disseminated the interim guidance/methodology to licensees in November 2001 (References 5 and 6). Licensees have subsequently used this methodology as the technical basis to support risk-informed, performance-based, one-time ILRT interval extensions to 15 years at approximately 75 operating reactors. The NRC approved these extensions through routine plant-specific license amendment requests.

In December 2003, the NEI submitted draft NEI TR 94-01, Revision 1, and EPRI Report No. 1009325, Revision 0, to support an industry effort to extend the ILRT surveillance interval to 20 years. The technical basis for the 20-year extension relied heavily on the use of new containment leakage probability values developed through an expert elicitation conducted by EPRI. Following the NRC staffs identification of a number of concerns regarding the expert elicitation, EPRI subsequently withdrew EPRI Report No. 1009325, Revision 0.

By letter dated December 19, 2005, the NEI submitted NEI TR 94-01, Revision 1, Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J, and EPRI Report No. 1009325, Revision 1, December 2005, Risk Impact Assessment of Extended Integrated Leak Rate Testing Intervals (Reference 7) for NRC staff review. EPRI Report No. 1009325, Revision 1, provided a generic assessment of the risks associated with a more limited, permanent performance-based extension of the ILRT surveillance interval to 15 years, and a risk-informed methodology/template to be used by licensees to confirm the risk impact of the ILRT extension on a plant-specific basis. The methodology is substantially similar to the NEI interim guidance/methodology, with minor enhancements to reflect experience from the analyses and reviews of one-time ILRT extensions and to reflect additional leak rate data from 35 recently completed ILRTs.

By letter dated February 21, 2007 (Reference 8), the NRC staff submitted a request for additional information (RAI) identifying information needed to continue the review. By letter dated May 25, 2007 (Reference 9), the NEI submitted its RAI responses. Because of the RAI responses, NEI TR 94-01, Revision 1, and EPRI Report No. 1009325, Revision 1, were revised to address NRC staff comments and recommendations. By letter dated August 31, 2007, the NEI submitted TR 94-01, Revision 2, Industry Guideline For Implementing Performance-Based Option of 10 CFR Part 50, Appendix J, and EPRI Report No. 1009325, Revision 2, August 2007, Risk Impact Assessment of Extended Integrated Leak Rate Testing Intervals (Reference 10), to the NRC staff for review.

NEI TR 94-01, Revision 2, describes an approach for implementing the optional performance-based requirements of Option B described in 10 CFR Part 50, Appendix J, which includes provisions for extending Type A ILRT intervals up to 15 years and incorporates the regulatory positions stated in RG 1.163. It delineates a performance-based approach for determining Type A, Type B, and Type C containment leakage rate surveillance testing frequencies. This method uses industry performance data, plant-specific performance data, and risk insights in determining the appropriate testing frequency. NEI TR 94-01, Revision 2, also discusses the performance factors that licensees must consider in determining test intervals. However, it does not address how to perform the tests because these details can be found in existing documents (e.g., ANSI/ANS-56.8-2002) (Reference 11).

Page of 13 EPRI Report No. 1009325, Revision 2, provides a risk impact assessment for optimized ILRT intervals of up to 15 years, utilizing current industry performance data and risk-informed guidance, primarily Revision 1 of RG 1.174, An Approach for using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis (Reference 12).

By letter dated June 25, 2008 (Reference 13), the NRC staff issued a SE for NEI TR 94-01, Revision 2, and companion EPRI Report No. 1009325, Revision 2. The SE documents the NRC staffs evaluation and acceptance of NEI TR 94-01, Revision 2, and EPRI Report No.

1009325, Revision 2, subject to the limitations and conditions identified in the SE and summarized in Section 4.0 of the June 25, 2008 SE.

The staff requested NEI to publish an approved version of NEI TR 94-01, which would incorporate the SE. As a result, NEI TR 94-01, Revision 2-A, Industry Guideline for Implementing Performance Based Option of 10 CFR 50, Appendix J, was issued in October 2008 (Reference 14) by NEI.

NEI identified a concern with the grace period for testing the Type C components as described in NEI TR 94-01, Revision 2-A and by letter dated September 2, 2009 (Reference 15), the NEI submitted NEI TR 94-01, Revision 2-A Supplement 1, Industry Guideline for Implementing Performance Based Option of 10 CFR 50, Appendix J, for NRC staff review. NEI TR 94-01, Revision 2-A Supplement 1 requested that the NRC staff approve a return to the original wording contained in the previous version of NEI TR 94-01. Based on several conference calls held with the NEI, the NRC staff noted a difference in understanding between the NEI and the NRC staff as to the intent and use of the grace period contained in the original wording.

The NRC staffs position in this regard is contained in RG 1.163 as stated above and in the final rule published in the Federal Register/Vol. 60, No. 186/Tuesday, September 26, 1995/Rules and Regulations (60FR49495) regarding the risk-informed regulation based on the performance history of components (containment, penetrations, valves) as a means to justify an increase in the interval for Type A, B, and C tests:

Type B & Type C Test Interval (1) Allow local leakage-rate test (LLRTs) intervals to be established based on the performance history of each component; (2) the performance criterion for the tests will continue to be the allowable leakage rate (La); (3) Specific performance 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 taken exception to the NEI guideline allowing the extension of Type C test intervals up to 10 years, and limits such extension to 5 years.

In establishing the 5-year test interval for LLRTs, the NRC has designed a cautious, evolutionary approach as data are compiled to minimize the uncertainty now believed to exist with respect to LLRT data. The NRCs judgment, based on risk assessment and deterministic analysis, continues to be that the limited data base on unquantified leakages and common mode repetitive failures introduces significant uncertainties into the probabilistic risk analysis. The NRC will be open to submittals from licensees as more performance-based data are developed. The extension of LLRT test interval to

Page of 13 5 years is a prudent first step. By allowing a 25 percent margin in testing frequency requirements, the NRC has provided the flexibility to accommodate longer fuel cycles.

Based on the above, the NRC staffs view is that the original intent was that tests were not supposed to be scheduled automatically using the interval plus grace period to routinely stretch the interval to the next refueling outage after the sixty months (5 years) allowed interval. The NEI position expressed in their September 2, 2009, letter was that the original intent was that the grace period allowed a permanent interval extension for plants on a 24-month cycle to test every third refuel outage.

By letter dated December 3, 2009 (Reference 16), the NRC staff submitted a RAI identifying information needed to continue review. By letter dated March 29, 2011 (Reference 17), the NEI submitted a package that included three attachments: (1) RAI responses from the December 3, 2009, letter as well as other responses made to comments identified during several conference call interactions; (2) an interim report on a project initiated by EPRI to collect and analyze recent (since 1996)Type C LLRT performance data; and (3) a proposed Revision 3 to NEI TR 94-01, Industry Guideline for Implementing Performance Based Option of 10 CFR 50, Appendix J.

After receiving comments from the NRC staff in a letter dated April 21, 2011 (Reference 18),

NEI submitted NEI TR 94-01, Revision 3, in a letter dated June 9, 2011 (Reference 19).

1.2 Purpose This SE documents the NRC staffs evaluation and acceptance of NEI TR 94-01, Revision 3, subject to the limitations and conditions identified in Section 4 of this SE and summarized in Section 5.0.

NEI TR 94-01, Revision 3, includes guidance for extending Type C LLRT surveillance intervals beyond sixty months. Section 3.0 of this SE provides the NRC staff position on the adequacy of NEI TR 94-01, Revision 3, in addressing the performance-based Type C test frequencies.

The NRC staff reviewed NEI TR 94-01, Revision 3, to determine whether its guidance will provide reasonable assurance that Type C local leak rate testing at an extended periodicity will ensure that Type C components maintain their intended functions during the period of extended operation. The review also considered compliance with regulatory requirements in 10 CFR Part 50.

1.3 Organization of the Safety Evaluation Section 2.0 of this SE summarizes the regulatory position. Section 3.0 documents the staffs technical evaluation and findings pertaining to the adequacy of NEI TR 94-01, Revision 3. In particular, Section 3.0 documents any staff concerns with the TR and the basis for limitations and conditions being placed on the use of the TR by applicants/licensees who choose to implement the NRC-approved version of NEI TR 94-01, Revision 3. Section 4.0 summarizes the limitations and conditions. Section 5.0 provides the conclusions resulting from this SE.

Page of 13

2.0 REGULATORY EVALUATION

The regulation at 10 CFR 50.54(o), requires primary reactor containments for water-cooled power reactors to be subject to the requirements of Appendix J to 10 CFR Part 50, Leakage Rate Testing of Containment of Water Cooled Nuclear Power Plants. Appendix J specifies containment leakage testing requirements, including the types of tests required to ensure the leak-tight integrity of the primary reactor containment and systems and components that penetrate the containment. In addition, Appendix J discusses leakage rate acceptance criteria, test methodology, frequency of testing, and reporting requirements for each type of test.

In 1995, the NRC amended the regulations to provide an Option B to the 10 CFR Part 50, Appendix J. Option B requires that test intervals for Type A, Type B, and Type C testing be determined by using a performance-based approach. Performance-based test intervals are based on consideration of operating history of the component and resulting risk from its failure.

Performance-based for Appendix J refers to both the performance history necessary to extend test intervals as well as the criteria necessary to meet the requirements of Option B.

Type A tests focus on verifying the leakage integrity of a passive containment structure. Type B and C testing focuses on assuring that containment penetrations are essentially leak tight.

These tests collectively satisfy the requirements of 10 CFR Part 50, Appendix J, Option B summarized as follows: 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.

NEI TR 94-01, Revision 3, provides guidance for implementing the Appendix J performance-based requirements and incorporates, by reference, the provisions of ANSI/ANS-56.8-2002 and the requirements of Subsections IWE and IWL of Section XI of the American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel Code (Code) (References 20 and 21).

The ASME Code requirements are incorporated by reference in 10 CFR 50.55a, with modifications and limitations. The modifications and limitations vary in accordance with the edition and the addenda of the ASME Code as required by 10 CFR 50.55a.

3.0 TECHNICAL EVALUATION

3.1 Type C Containment Isolation Valve Performance In order to reduce the uncertainty and thereby allow for increasing the allowable extended interval, NEI obtained LLRT leak-tight performance data from industry (29 units) in order to validate the risk impact assessment of EPRI TR-104285, Risk Impact Assessment of Revised Containment Leak Rate Testing Intervals, August 1994 (Reference 22). NEI states that with this validated assessment, it justifies increasing allowable extended LLRT intervals to the 120 months specified in NEI 94-01, Revision 0. However, NEI is requesting that the allowable extended interval for Type C LLRTs be increased only to 75 months, to be conservative (also as a cautious evolutionary approach), with a permissible extension (for non-routine emergent conditions) of nine months (84 months total). See Limitation and Condition #1.

NEI collected data covering the period of 1996-2010 for leak-tight performance of Type C containment isolation valves on extended intervals and presented them in EPRI Report

Page of 13 No. 1022599, Type C Containment Isolation Valve Performance, January 2011 (Reference 23). This report concludes that the leak-tight performance of Type C containment isolation valves tested on extended intervals after 1995 is significantly better than the leak-tight performance of the general population of Type C valves tested before 1995. This report shows that the failure rate for valves tested on extended intervals (after implementation of NEI 94-01 in 1995) was about an order of magnitude less than that reported in EPRI TR-104285 and in NUREG-1493 for the general population of valves tested before the 1995 time frame.

A failure is defined as a valve exceeding its administrative leakage limit as defined in Section 10.2 of NEI 94-01, which requires administrative limits be established and maintained in accordance with ANSI/ANS-56.8-2002, Sections 6.5 and 6.5.1. The staff has determined that these requirements, including those for periodic review (e.g., maintenance) provide sufficient guidance and assurance for compliance. The reported instances of exceeding administrative limits (failures) on redundant valves were only 4.7 percent of the reported failures, which is a very small number; as is the pathway leakage rate, and in no case was the 0.6La criterion exceeded.

As referred to in NEI 94-01, EPRI TR-104285 provided a risk impact assessment of alternative testing intervals for both ILRT and LLRT. Risk involved in conducting Type C LLRTs on extended intervals (using population dose as the metric) was determined using valve leakage performance data obtained from industry by the NEI. This pre-1995 data was very conservatively applied in the risk impact assessment by assuming that the leakage magnitude for a penetration would be that associated with the valve in the penetration that exceeded its administrative limit. As stated above, the recent (post-1995) failure rate data indicates that the failure rate of Type C valves tested on extended intervals was significantly less than the failure rate for the general population of Type C valves tested pre-1995. NEI states that this 1994 risk impact assessment remains conservative and valid based on the application of this recent data to assess the risk involved with testing valves that qualify for testing on extended intervals in accordance with NEI 94-01. The NRC staff agrees.

During a preliminary review of the EPRI TR-1022599, the NRC staff concluded that the EPRI focus was on LLRT individual failures (each plants staff determines what leakage value results in a failure for each of their valves) with little attention to how close units operate to the 0.6 La combined Type B and C TS leakage criterion. The staff was concerned how this may incorrectly result in a condition for desired routine scheduling of Type C tests beyond 60 months, and may result in an understatement of the min-pathway total. To address the staffs concern, Section 12.1, Report Requirements, of NEI TR 94-01, was revised in Revision 3 to require that the post-outage report shall include the margin between the Type B and Type C leakage rate summation and its regulatory limit. It further states that adverse trends in the Type B and Type C leakage rate summation shall be identified in the report and a corrective action plan developed to restore the margin to an acceptable level. The NRC staff finds the revision to Section 12.1, Report Requirements, of NEI TR 94-01, Revision 3 to be acceptable with the condition identified in Section 4.0 of this SE. See Limitation and Condition #2.

3.2 NRC Staff Evaluation of NEI TR 94-01, Revision 3 The purpose of NEI TR 94-01, Revision 3, is to assist licensees in the implementation of Option B to 10 CFR Part 50, Appendix J, and in extending Type C LLRT intervals beyond 60 months. Specifically, NEI TR 94-01, Revision 3, includes guidance that would permit licensees

Page of 13 to permanently extend the Type C LLRT surveillance intervals to 75 months. It delineates a performance-based approach for determining Type A, Type B, and Type C containment leakage rate testing frequencies. The failure of any Type C tests would reset the testing frequency back to 30 months until performance history is re-established.

The reactor containment leakage test program includes performance of an ILRT, also termed as a Type A test; and performance of LLRTs, also termed as either Type B or Type C tests. The Type A test measures the overall leakage rate of the primary reactor containment. Type B tests are intended to detect leakage paths and measure leakage rates for primary reactor containment penetrations. Type C tests are intended to measure containment isolation valve leakage rates.

Sections 3.2.1 through 3.2.3 of this SE provide the NRC staffs evaluation of the adequacy of NEI TR 94-01, Revision 3, for addressing the performance-based Type C test frequencies.

3.2.1 Performance-Based Type C Test (LLRT) Frequencies Individual licensees may adopt a testing interval and approach provided that certain performance factors and programmatic controls are reviewed and applied as appropriate. The performance factors that have been identified as important, and that should be considered in establishing testing intervals, include past performance, service design, safety impact, and cause determination. A licensee should develop bases for new frequencies based upon satisfactory performance of leakage tests that meet the requirements of 10 CFR Part 50, Appendix J. Additional considerations used to determine appropriate frequencies may include service life, environment, past performance, design, and safety impact.

3.2.2 Type C Performance Leakage Rate Leakage rates less than the administrative leakage rate limits are considered acceptable to the NRC staff. Administrative limits for leakage rates shall be established, documented, and maintained for each Type C component prior to the performance of LLRT in accordance with the guidance provided in ANSI/ANS-56.8-2002, Sections 6.5 and 6.5.1. Administrative limits are specific to individual penetrations or valves, and not the surveillance acceptance criteria for Type C tests. Acceptance criteria for the combined leakage rate for all penetrations subject to Type C testing should be defined in accordance with ANSI/ANS-56.8-2002, Sections 6.4 and 6.5.

3.2.3 Extending Type C Test Intervals The regulation at 10 CFR Part 50, Appendix J, states that Type C tests shall be performed prior to initial reactor operation. In accordance with the guidance in NEI TR 94-01, Revision 3, subsequent periodic Type C tests shall be performed at a frequency of at least once per 30 months, until adequate performance history is established. Extensions of Type C test intervals are allowed based upon completion of two consecutive periodic as-found tests where the results of each test are less than a licensees allowable administrative limits.

NEI TR 94-01, Revision 3 (page iv, Executive Summary) states that: Intervals may be increased from 30 months up to a maximum of 75 months for Type C tests If a licensee considers extended test intervals of greater than 60 months for Type C tested components,

Page of 13 the review should include the additional considerations of as-found tests, schedule and review...

If the Type C test results are not acceptable, the test frequency should be set at the initial test intervals. Once the cause determination and corrective actions have been completed, acceptable performance may be reestablished and the testing frequency returned to the extended intervals.

NEI TR 94-01, Revision 3, Section 10.2.3.3 (Type C testing) stipulates that the performance of these tests shall be performed at a frequency of at least once per 30 months if a penetration is replaced or engineering judgment determines that modification of a penetration has invalidated the valves performance history; and that testing shall continue at this frequency until an adequate performance history is established.

NEI TR 94-01, Revision 3, Section 10.1, states that the: intervals of up to 75 months for the recommended surveillance frequency for Type C testing given in this section may be extended by up to 25 percent of the test interval, not to exceed nine months. The NRC staff agrees with this extension as being consistent with scheduling practices for TS.

3.3 The Impact of the Proposed Change Should be Monitored Using Performance Measurement Strategies As documented in NUREG-1493, industry experience has shown that most ILRT failures result from leakage that is detectable by local leakage rate testing (Type B and C testing). Specific testing frequencies for the LLRT are reviewed prior to every refueling outage. An outage scope document is issued to document the LLRT periodically and to ensure that all pre-maintenance and post-maintenance testing is complete.

The post-outage report provides a written record of the extended testing interval changes and the reasons for the changes based on testing results and maintenance history. Based on the above measures, the LLRT program will provide continuing assurance that the most likely sources of leakage will be identified and repaired.

ANSI/ANS-56.8-2002, Section 6.4.4, also specifies surveillance acceptance criteria for Type B and Type C tests and states that: "The combined [as-found] leakage rate of all Type B and Type C tests shall be less than 0.6La when evaluated on a minimum pathway leakage rate basis, at all times when containment operability is required." It states, moreover, that: "The combined leakage rate for all penetrations subject to Type B and Type C test shall be less than or equal to 0.6La as determined on a maximum pathway leakage rate basis from the as-left LLRT results." These combined leakage rate determinations shall be done with the latest leakage rate test data available, and shall be kept as a running summation of the leakage rates.

The combined leakage rate determination should also be incorporated in every post-outage report.

The containment components' monitoring and maintenance activities will be conducted according to the requirements of 10 CFR Part 50, Appendix J, and 10 CFR Part 50.55a.

The above provisions are considered acceptable performance monitoring strategies for assuring that the risk of the proposed change will remain small.

Page of 13 4.0 LIMITATIONS AND CONDITIONS The NRC staff finds that the guidance in NEI 94-01, Revision 3, is acceptable for referencing by licensees in the implementation for the optional performance-based requirements of Option B to 10 CFR Part 50, Appendix J. However, the NRC staff identified two conditions on the use of NEI 94-01, Revision 3:

1. NEI TR 94-01, Revision 3, is requesting that the allowable extended interval for Type C LLRTs be increased to 75 months, with a permissible extension (for non-routine emergent conditions) of nine months (84 months total). The staff is allowing the extended interval for Type C LLRTs be increased to 75 months with the requirement that a licensees post-outage report include the margin between the Type B and Type C leakage rate summation and its regulatory limit. In addition, a corrective action plan shall be developed to restore the margin to an acceptable level. The staff is also allowing the non-routine emergent extension out to 84-months as applied to Type C valves at a site, with some exceptions that must be detailed in NEI 94-01, Revision 3. At no time shall an extension be allowed for Type C valves that are restricted categorically (e.g. BWR MSIVs), and those valves with a history of leakage, or any valves held to either a less than maximum interval or to the base refueling cycle interval. Only non-routine emergent conditions allow an extension to 84 months. This is Topical Report Condition 1.

2. The basis for acceptability of extending the ILRT interval out to once per 15 years was the enhanced and robust primary containment inspection program and the local leakage rate testing of penetrations. Most of the primary containment leakage experienced has been attributed to penetration leakage and penetrations are thought to be the most likely location of most containment leakage at any time. The containment leakage condition monitoring regime involves a portion of the penetrations being tested each refueling outage, nearly all LLRTs being performed during plant outages. For the purposes of assessing and monitoring or trending overall containment leakage potential, the as-found minimum pathway leakage rates for the just tested penetrations are summed with the as-left minimum pathway leakage rates for penetrations tested during the previous 1 or 2 or even 3 refueling outages. Type C tests involve valves which, in the aggregate, will show increasing leakage potential due to normal wear and tear, some predictable and some not so predictable. Routine and appropriate maintenance may extend this increasing leakage potential. Allowing for longer intervals between LLRTs means that more leakage rate test results from farther back in time are summed with fewer just tested penetrations and that total used to assess the current containment leakage potential. This leads to the possibility that the LLRT totals calculated understate the actual leakage potential of the penetrations. Given the required margin included with the performance criterion and the considerable extra margin most plants consistently show with their testing, any understatement of the LLRT total using a 5-year test frequency is thought to be conservatively accounted for. Extending the LLRT intervals beyond 5 years to a 75-month interval should be similarly conservative provided an estimate is made of the potential understatement and its acceptability determined as part of the trending specified in NEI 94-01, Revision 3, Section 12.1.

When routinely scheduling any LLRT valve interval beyond 60-months and up to 75-months, the primary containment leakage rate testing program trending or monitoring

Page of 13 must include an estimate of the amount of understatement in the Type B & C total, and must be included in a licensees post-outage report. The report must include the reasoning and determination of the acceptability of the extension, demonstrating that the LLRT totals calculated represent the actual leakage potential of the penetrations. This is Topical Report Condition 2.

5.0 CONCLUSION

S The NRC staff reviewed NEI TR 94-01, Revision 3, and determined that it describes an acceptable approach for implementing the optional performance-based requirements of Option B to 10 CFR Part 50, Appendix J, as modified by the conditions and limitations summarized in Section 4.0 of this SE. This guidance includes provisions for extending Type C LLRT intervals up to 75 months. Type C testing ensures that individual containment isolation valves are essentially leak tight. In addition, aggregate Type C leakage rates support the leakage tightness of primary containment by minimizing potential leakage paths.

The NRC staff, therefore, finds that this guidance, as modified to include two limitations and conditions, is acceptable for referencing by licensees proposing to amend their TS in regards to containment leakage rate testing. Any applicant may reference NEI TR 94-01, Revision 3, as modified by this SE and approved by the NRC, in a licensing action to satisfy the requirements of Option B to 10 CFR Part 50, Appendix J. The NRC staff is not required to repeat its review of the matters described in the TR conditioned upon the changes described in this SE (Sections 3 and 4) to be incorporated when the report appears as a reference which was complied with a request for relief, or other related licensing actions.

Before endorsement by the NRC, the TR must be updated to reflect the correction of the issues described in Sections 3 and 4, and incorporation of both limitations and conditions, into the body of the TR.

6.0 REFERENCES

The following reports and supporting information were used by the staff as part of its review of the NEI TR 94-01, Revision 3.

1. NEI TR 94-01, Revision 0, AIndustry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J, July 26, 1995 (ADAMS Legacy Library Accession No. 9510200180).

2. U.S. Nuclear Regulatory Commission, APerformance-Based Containment Leak-Test Program,@ Regulatory Guide 1.163, September 1995 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML003740058).

3. U.S. Nuclear Regulatory Commission, Performance-Based Containment Leak-Test Program, NUREG-1493, July 1995.

4. Electric Power Research Institute, ARisk Impact Assessment of Revised Containment Leak Rate Testing Intervals, Report No. 104285, Palo Alto, California, August 1994.

Page of 13

5. A. R. Pietrangelo, NEI, memorandum to NEI Administrative Points of Contact, November 13, 2001.

6. A. R. Pietrangelo, NEI, memorandum to NEI Administrative Points of Contact, November 30, 2001.

7. A. R. Pietrangelo, NEI, letter to Document Control Desk, U.S. Nuclear Regulatory Commission, December 19, 2005 (ADAMS Package Accession No. ML053610177).

8. T. M. Mensah, U.S. Nuclear Regulatory Commission, letter to J. H. Riley, NEI, February 21, 2007 (ADAMS Accession No. ML062910258)

9. J. C. Butler, NEI, letter to T. M. Mensah, U.S. Nuclear Regulatory Commission, May 25, 2007 (ADAMS Package Accession No. ML071590201).

10. J. C. Butler, NEI, letter to T. M. Mensah, U.S. Nuclear Regulatory Commission, August 31, 2007 (ADAMS Package Accession No. ML072970204).

11. American Nuclear Society, Containment System Leakage Testing Requirements, ANSI/ANS 56.8-2002, LaGrange Park, Illinois.

12. U.S. Nuclear Regulatory Commission, AAn Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis,@ Regulatory Guide 1.174, Revision 1, November 2002 (ADAMS Accession No. ML023240437.

13. M. J. Maxin, U.S. Nuclear Regulatory Commission, letter to J. C. Butler, NEI, June 25, 2008 (ADAMS Accession No. ML081140151).

14. NEI TR 94-01, Revision 2-A, Industry Guideline for Implementing Performance Based Option of 10 CFR 50, Appendix J, October 2008.

15. J. H. Riley, NEI, letter to T. M. Mensah, U.S. Nuclear Regulatory Commission, September 2, 2009 (ADAMS Accession No. ML0925803830).

16. T. M. Mensah, U.S. Nuclear Regulatory Commission, letter to J. H. Riley, NEI, December 3, 2009 (ADAMS Accession No. ML093340541).

17. B. Bradley, NEI, letter to S. D. Stuchell, U.S. Nuclear Regulatory Commission, March 29, 2011.

18. S. D. Stuchell, U.S. Nuclear Regulatory Commission, letter to B. Bradley, NEI, April 21, 2011.

19. B. Bradley, NEI, letter to S. D. Stuchell, U.S. Nuclear Regulatory Commission, June 9, 2011.

20. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code,Section XI, Subsection IWE, Requirements for Class MC and Metallic Liners of Class

Page of 13 CC Components of Light-Water Cooled Plants.

21. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code,Section XI, Subsection IWL, Requirements for Class CC Concrete Components of Light-Water Cooled Plants.

22. EPRI TR-104285, Risk Impact Assessment of Revised Containment Leak Rate Testing Intervals, August 1994.

23. EPRI report No. 1022599, Type C Containment Isolation Valve Performance, January 2011.

Principal Technical Contributor: Brian Lee Date: May 8, 2012