ML20128G293

Safety Evaluation Supporting Amend 135 to License NPF-12

ML20128G293
Person / Time
Site:	Summer
Issue date:	10/02/1996
From:	NRC (Affiliation Not Assigned)
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NUDOCS 9610080427
Download: ML20128G293 (4)

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l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.135 TO FACILITY OPERATING LICENSE NO. NPF-12 SOUTH CAROLINA ELECTRIC & GAS COMPANY SOUTH CAROLINA PUBLIC SERVICE AUTHORITY VIRGIL C. SUMMER NUCLEAR STATION. UNIT N0. 1 DOCKET NO. 50-395

1.0 INTRODUCTION

l On September 12, 1995, the U.S. Nuclear Regulatory Commission (NRC) approved issuance of a revision to 10 CFR Part 50, Appendix J, " Primary Reactor Containment Leakage Testing fur Water-Cooled Power Reactors" which was <

i subsequently published in the Federal Reaister on September 26, 1995, and became effective on October 26, 1995. The NRC added Option B " Performance-Based 1 Requirements" to allow licensees to voluntarily replace the prescriptive testinU requirements of 10 CFR Part 50, Appendix J, with testing requirements based on both overall leakage rate performance and the performance of individual components. l 1

By application dated April 16, 1996, as supplemented by letter July 25, 1996, South Carolina Electric & Gas Company (SCE&G)(the licensee) requested changes to the Technical Specifications (TS) for the Virgil C. Summer Nuclear Station (VCSNS). The proposed changes would permit implementation of 10 CFR Part 50, Appendix J, Option B. The licensee has established a " Containment Leakage Rate  !

Testing Program" and proposed adding this program to the TS. The program i references Regulatory Guide (RG) 1.163, " Performance-Based Containment Leak Test j Program," which specifies a method acceptable to the NRC for complying with i Option B dated September 1995,

2.0 BACKGROUND

Compliance with 10 CFR Part 50, Appendix J, provides assurance that the primary containment, including those systems and components which penatrate the primary containment, do not exceed the allowable leakage rate specified in the TS and J Bases. The allowable leakage rate is determined so that the leakage assumed in the safety analyses is not exceeded.

On February 4,1992, the NRC published a notice in the Federal Reaister (57 FR 4166) discussing a planned initiative to begin eliminating requirements marginal to safety which impose a significant regulatory burden. Appendix J of 10 CFR Part 50 was considered for this initiative and the staff undertook a study of 9610080427 961002 PDR ADOCK 05000395 P PDR

2 possible changes to this regulation. The study examined the previous performance history of domestic containments and examined the effect on risk of a revision to the requirements of Appendix J. The results of this study ,

are reported in NUREG-1493, " Performance-Based Leak-Test Program."

l Based on the results of this study, the staff developed a performance-based l approach to containment leakage rate testing. On September 12, 1995, the NRC i approved issuance of this revision to 10.CFR Part 50, Appendix J, which was  !

subsequently published in the Federal Reaister on September 26, 1995, and became  !

effective on October 26, 1995. The revision added Option B " Performance-Based {

Requirements" to Appendix J to allow licensees to voluntarily replace the l prescriptive testing requirements of Appendix J with testing requirements based  !

on both overall and individual component leakage rate performance. '

Regulatory Guide 1.163 was developed as a method acceptable to the NRC staff for- j implementing Option B. This regulatory guide states that the Nuclear Energy .

Institute (NEI) guidance document NEI 94-01, " Industry Guideline for I Implementing Performance-Based Option of 10 CFR Part 50, Appendix J" provides  :

methods acceptable to the NRC staff for complying with Option B with fcur  !

exceptions which are described therein. i

! Option B requires that the RG or other implementation document used by a I l licensee to develop a performance-based leakage rate testing program must be L included, by general reference, in the plant TS. The licensee has referenced RG j l 1.163 in the VCSNS TS. I I l l

Regulatory Guide 1.163 specifies an extension in Type A test frequency to at l 1 east one test in 10 years based upon two consecutive successful tests. Type B tests may be extended up to a maximum interval of 10 years based upon completion l of two consecutive successful tests and Type C tests may be extended up to 5 t

years based on two consecutive successful tests.

By letter dated October 20, 1995, NEI proposed TS to implement Option B. After some discussion,. the staff and NEI agreed on final TS which were attached to a letter from C. Crimes (NRC) to D. Modeen (NEI) dated November 2, 1995. These TS are to serve as a edel for licensees to develop plant-specific TS in preparing amendment requests to fe.nlement Option B.

For a licensee to determine the performance of each component, factors that are

! indicative of or affect performance, such as an administrative leakage limit, must be established. The administrative limit is selected to be indicative of the potential onset of component degradation. Although these limits are subject to NRC inspection to assure that they are selected in a reasonable manner, they )

are not TS rec drements. Failure to meet an administrative limit requires the licensee to return to the sinimum value of the test interval.

Option B requires that the licensee maintain records to show that the criteria for Type A, B and C tests have been met. In addition, the licensee must

! maintain comparisons of the performance of the overall containment system and

the individual components to show that the test intervals are adequate. These i records are subject to NRC inspection.

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3 3.0 EVALUATION The licensee's letter to the NRC dated April 16, 1996, as supplemented by letter July 25, 1996, proposes to establish a " Containment Leakage Rate Testing Program" and proposes to add this program to the TS. The program references RG 1.163, which specifies a method acceptable to the NRC for complying with Option B. This requires a change to existing TS 1.7d, 4.6.1.lc, 3.6.1.2, 4.6.1.2, 4.6.1.2a, 4.6.1.2b, 4.6.1.2c, 4.6.1.2d, 4.6.1.2e, 4.6.1.2f, 4.6.1.29, 3.6.1.3, 4.6.1.3a, 4.6.1.3b, 4.6.1.3d, 4.6.1.6.3, 4.6.1.7.3, and the addition of the

" Containment Leakage Rate Testing Program" to Section 6.8.49 Corresponding Bases 3/4.6.1.3 and 3/4.6.1.7 were also modified.

Option B permits a licensee to choose Type A; or Type B and C; or Type A, B and C testing to be done on a performance basis. The licensee has elected to perform Type A, B and C testing on a performance basis.

The TS changes proposed by the licensee are in compliance with the requirements of Option B and consistent with the guidance of RG 1.163, and the generic TS of the Novecber 2, 1995, letter and are, therefore, acceptable to the staff.

The licensee's April 16, 1996 submittal, as supplemented on July 25, 1996, also proposed revising TS surveillance requirement 4.6.1.7.3 dealing with the frequency of leakage rate testing the containment purge supply and exhaust isolation valves. These valves use resilient seals. The licensee proposed to extend the present test intervals of 6 months to 30 months following the guidance of Regulatory Guide 1.163, " Performance-Based Leak-Test Program", dated l

September 1995. Regulatory Guide 1.163 recommends testing of containment purge and vent valves at intervals not exceeding 30 months. However, the current test interval is not based on Appendix J considerations and the licensee's proposal is therefore outside the scope of the proposed change to Option B. The current l test intervals are based on the findings of Generic Issue B-20, " Containment Leakage Due to Seal Degradation", that valves with resilient seals should be l

tested more frequently than required by Appendix J. The background for this conclusion is discussed in IE Circular 77-11 " Leakage of Containment Isolation i Valves With Resilient Seats", issued on September 6, 1977.

IE Circular 77-11 determined the cause of excessive leakage to be either general degradation of the resiliency characteristics of the seal, cold temperature and the associated " hardening" of the seal, or a combination of the two. In these l cases examination of the resilient valve seat material indicated that the

! material had hardened and lost resiliency and showed signs of wear due to valve l cycling. Exposure to various environmental conditions such as humidity and temperature apparently accelerated the degradation or changed the performance characteristics of the seating material. IE Circular 77-11 indicated that a l life expectancy of the resilient seats is at best about 3 years and may be less  ;

dependent upon specific conditions to which they are subjected.

i After some discussion with the staff, the licensee provided information on the performance of these valves in a letter to the NRC dated July 25, 1996. The  ;

information demonstrated that purge supply and exhaust valves at VCSNS do not l have a higher failure rate than other containment valves. A review of the data from the licensee's as-found testing, from 1990 to 1996, found no failures of leakage rate tests of these valves. The data indicate the leakage acceptance criteria were well met. The staff concludes that the valve performance, supported by historical test data, is an acceptable basis for the proposed

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extended test interval of TS surveillance requirement 4.6.1.7.3. The staff therefore finds the licensee's proposal acceptable.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the State of South Carolina I official was notified of the proposed issuance of the amendment. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the ,

amendment involves no significant increase in the amounts, and no significant  !

change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (61 FR 34898). Accordingly, the amendment meets the r?igibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that l (1) there is reasonable assurance that the health and safety of the public will i not be endangered by operation in the proposed manner, (2) such activities will l be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: R. Lobel, NRR Date: October 2,1996 I

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