ML20197A614
| ML20197A614 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 02/26/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20197A606 | List: |
| References | |
| NUDOCS 9803090307 | |
| Download: ML20197A614 (6) | |
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UNITED STATES NUCLEAR REGULATORY COMMIMlON WASHINGTON, D.C. 30006 4001-
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SAFETY EVALUATION BY THE OFPCE OF NUCLEAR REACTOR REGULATION i
RELATED TO AMENDMENT NO.152TO FACILITY OPERATING LICENSE NO. DPR 28 VERMONT YANKEE NUCLEAR POWER CORPORATION VERMONT YANKEE NUCLEAR POWER STATION DOCKET NO. 50-271
1.0 INTRODUCTION
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 for Water-Cooled Power Reactors" which was subsequently published in the Federal Reaister on September 26,1995, a.d became effective on October 26,1995.
The NRC added Option B " Performance-Based Requirements," to allow licensees to voluntarily replace the prescriptive testing requirements of 10 CFR Part 50, Append!x J, with testing requirements based on both overall performance and the performance of individual L
components.
By application dated July 11,1997, as supplemented by letters dated November 21, December 22,1997, and February 6,1998, Vermont Yankee Nuclear Power Corporation
. (the licensee) requested changes to the Technical Specifications (TS) for the Vermont Yankee Nuclear Power Station. The November 21, December 22,1997, and February 6,-
1998, letters did not change the initial proposed no significant hazards determination. The proposed changes would permit implementation of 10 CFR Part 50, Appendix J, Option B, and reference Regulatory Guide (RG) 1.163, " Performance-Based Containment Leak-Test Program," dated September 1995, which specifies a method acceptable to the NRC for complying with Option B.
2.0 BACKGROUND
Compliance with 10 CFR Part 50, Appendix J, provides assurance that the primary containment, including those systems and components which penetrate the primary containment, do not exceed the allowable leakage rate specified in the TS and Bases. The allowable leakage rate is determined so that the leakage rate assumed in the safety analyses is not exceeded.
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2-On February 4,1992, the NRC published a notice in the Federal Register (57 FR 4166) discussing a planned initiative to begin eliminating requirements marginal to safety which impose a significant regulatory burden.10 CFR Part 50, Appendix J, " Primary Containment 4
Leakage Testing for Water-cooled Power Reactors," was considered for this initiative and the staff undertook a study of 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 Apperwhx J. The results of this stud are reported in f
NUREG-1493, " Performance-Based Leak-Test Program."
Based on the results of this study, the staff developed a performance-based approach to containment leakage rate testing. On September 12,1995, the NRC approved issuance of this revision to 10 CFR Part 50, Appendix J, which was subsequently published in the Federal Reglater 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 prescriptive testing requirements of Appendix J with testing requirements based on both overall and individual f.amponent leakage rate performance.
The RG 1.163, " Performance-Based Containment Leak Test Program," da+rd September 1995, was developed as a method acceptable to the NRC staff for impiomenting Option B.
This regulatnry guide states that the Nuclear Energy Institute (NEI) guidance document NEl 94-01, Rev. O, " Industry Guideline for Implementing Performance-Based Option of 10 CFR l
Ps 150, Appendix J," provides methods acceptable to the NRC staff for complying with Option B with four exceptions which are described therein.
Option B requires that RG 1.163 or another implementation dot,ument used by a licenses to develop a performance-based leakage testing program must be included, by general reference, in the plant TS. The licensee has referenced RG 1.163 in the proposed Vermot;t Yankee TS.
RG 1.163 specifies an extension in Type A test frequency to at least 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 of two consecutive successful tests and Type C tests may be extended up to five years based on two consecutive successful tests.
By letter dated October 20,1995, NEl proposed TS to implement Option B. After some discussion, the staff and NEl agreed on final TS which were transmitted to NEl in a letter dated November 2,1995. - These TS are to serve as a model for licensees to develop plant-
- specific TS in preparing amendment requests to implement Option B.
In order 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 sC,ected 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 requirements. Failure to meet an administrative limit requires the licensee to retum to the minimum 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 i
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performance of the overall containment system and the individust components to show that the test intervals are adequate. These records are subject to NRC inspection.
3.0 EVALUATION The licensee's July 11, November 21, December 22,1997, and February 6,1998, letters to the NRC propose to establish a " Primary Containment Leakage Rote Testing program" and propose to add this program to the TS. The program references RG 1.163," Performance-Based Containment Leak Test Program," dated September 1995, which specifies methods acceptable to the NRC for complying with Option B. The licensee proposes changes to existing TOs 3.7.A.3, 3.7.A.4, 4.7.A.2, 4.7.A.3, 4.7.A.4, 3.7.D.1, 3.7.D.2, 4.7.D.2, Table 4.7.1, Table 4.7.2.a, and Table 4.7.2.b, and the addition of the " Primary Containment Leakage Rate Testing Program" as TS 6.15. Corresponding bases were also modified.
l Option B permits a licensee to choose Type A; or Type B and C; or Type A, B and C; testing l
to be done on a performance basis. The licensee has elected to perform Type A, B, and C l
testing on a performance basis.
The TS changes proposed by the licensee are in compliance with the requirements of Option B and are consistent with the guidance of RG 1.163. Further, the proposed TS i-changes generally conform to the model TS guidance provided in the NRC letter to NEl dated November 2,1995, despite the different format of the licensee's current TSs. The specific TS changes are discussed below in 3.1, Additionally, the licensee has proposed related TS changes which go beyond the scope of the conversion to Option B; these are discussed in 3.2, below.
3.1 OPTION B TS CHANGES Current TS 3.7.A.3 is being deleted, and TS 4.7.A.2 is being revised, to remove details l
about the testing program from these sections and to replace those details with a reference i
to the Primary Containment Leakage Rate Testing Program. This is consistent with the j
model TS guidance and is acceptable.
Current TSs 3.7.A.4 and 4.7.A.4 are being revised to remove a requirement that the leakage rate from any one containment isolation valve (CIV) shall not exceed 5 percent of the maximum allowable containment leak rate. This limitation goes beyond even the l
requirements of Option A of Appendix J, and beyond the requirements of Option B or the provisions of RG 1.163. As mentioned in section 2.0 above, the licensee must establish i
individual administrative limits for each CIV, but they are not TS requirements. Therefore, the staff finds this change to be acceptable, i-Current TSs 3.7.D.1,3.7.D.2, and 4.7.D.2 are being revised to remove references to TS tables that list CIVs. The revised TS will apply to all CIVs, rather than just those listed in TS tables. Further, TS Table 4.7.1, " Penetrations and Seals Subject to Type B Testing,"is being deleted, and Tables 4.7.2.a and 4.7.2.b, which are tables listing CIVs, are being revised so that they no longer indicate which valves are Type C tested. This is consistent l
with the provisions of GL 91-08, "Ramoval of Component Usts From Technica;
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4 Specifications," dateu May 6,1991, and with the m Wel TS for Option B implementation, which assume that component lists have already be an removed from the plant's TS.
Therefore, the staff finds these changes to be acceptable.
A new TS 6.15, " Primary Containment Leakage Rate Testing Program,"is being added to
- describe the program. It is consistent with the model TS, except that the licensee is proposing additional words, beyond the model TS, for the leakage rate acceptance criteria, to reflect these accep'soce criteria for as-left and as-found Type A leakage rates and combined Type B and C leakage rates. The model Bases for TS 3.6.1.1.1, state:
Reviewer's Note: Regulatory Guide 1.163 and NEl 94-01 include acceptance criteria for as-left and as-found Type A leakage rates and combined Type B and C leakage rates, which may be reflected in the Bases.
As an extension of this concept, the licensee is proposing to put the additional words into the TS itself. The staff has reviewed these additional words and finds that they are consistent with RG 1.163 and NEl 94-01, and are therefore acceptable.
Proposed TS 6.15 also deviates from the model TS in that it does not state a separate air lock leakage rate testing acceptance criterion for reduced-pressure door seal tests; it only gives an acceptance criterion for the overall, full-pressure test. At this plant, all air lock tests are performed at full pressure. The full-pressure test is a better test, in that it encompasses the entire air lock, rather than just the door seals, and the higher test pressure results in a more accurate leakage rate measurement end chellenges the components more than a reduced-pressure test. Therefore, the staff finds the proposed air lock acceptance criterion to be acceptable.
3.2 RELATED TS CHANGES TS 4.7.A.3 Current TS 4.7.A.3 requires that, before opening or breaking a closed piping system outside containment, which is connected to certain CIVs that are not Type C tested (in other words,-
a system that acts as an extension of containment), the isolation valves bounding the opening shall be Type C tested or else a blind flange shall be installed on the opening. The licensee proposes to delete this survoillance requirement and replace it with a new Limiting Condition For Operation (LCO) which says:
If a portion of a system that is considered to be an erension of primary containment is to be opened, isolate the affected penetration flow path bv use of at least one closed and deactivated automatic valve, closed manual valse or blind flange.
First, the staff agrees that this is more property an LCO than a surveillance requirement.
Second, the Improved Standard TS and the model TS for option B implementation both allow open penetration flow paths (usually due to inoperable CIVs) to be isolated by use of at least one closed and deactivated automatic valve, closed manual valve, or blind flange.
Third, the licensee states that the closed and deactivated automatic valves, closed manual valves, or blind flanges will be conta nment isolation devices and will be leak rate tested in
o 5-accordance with the Primary Containment Leakage Rate Testing Program. Therefore, the staff finds the proposed TS to be essentially equivalent to the existing TS and to represent no significant increase in risk to public health and safety; thus, it is acceptable.
3 Table 4.7.2 Ectorial Change Currently, TS Table 4.7.2 indicates that two of the containraent purge valves are normally open to support drywell-to-suppression chamber differential pressure control and suppression pool water level, in a 1978 letter, the licensee described their procedure, including the use of a pumpback system to maintain the differential pressure. Subsequently, the licensee changed the method and described a diffsrent purge / vent valve line-up in a 1982 letter. The staff accepted their proposal in a letter dated May 3,1982, but the TS table was not amended to reflect the fact that the two purgs valves shown as normally open would instead be normally closed, and two other, smaller valves (not currently listed in the table) would be normally open. Thus, the proposed change is editorial in nature.
All four valves are CIVs and receive automatic containsnent isolation signals to close in the event of an accident. The two valves, now to be normally open, are smaller and will close "g
faster than the two valves that were formerly open, so public risk will be slightly reduced.
On the basis given above, the staff finds the proposed changes to TS Table 4.7.2 to be acceptable.
3.3 WMMARY in summary, the staff has reviewed the changes to the TS and associated Bases proposed by the licensee, for Option B implementation, and finds that they are in compliance with the requirements of Ar andix J, Option B, and are consistent with the guidance of RG 1.163, and are therefore acceptable. Further, the staff finds the additional changes discussed in section 3.2 above to be acceptable on the bases discussed therein.
4.0 STATE CONCLUSION in accordance with the Commission's regulations, the Vermont State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATIOP' The amendment changes a requirement with respect to instaliation or use of a facility compcnent 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 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 (62 FR 45465). Accordingly, tha amendment meets the eligibility 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.
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6.9 Gsh'CLVfdG The Commission has concluded, based on the considerations discussed above, that (1) there is rossonable assurance that tht health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in comp;iance 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 Oontributor: J. Pulsipher o.t.:
February 26, 1998 4
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