ML20134N741
| ML20134N741 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 02/19/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20134N738 | List: |
| References | |
| NUDOCS 9702240414 | |
| Download: ML20134N741 (5) | |
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UNITED STATES s
j NUCLEAR REGULATORY COMMISSION k*****p#g WASHINGTON, D.C. 20086-0001 j
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENTS NO.126 AND NO.118 TO FACILITY OPERATING LICENSE NOS. DPR-42 AND DPR-60 NORTHERN STATES POWER COMPANY j
PRAIRIE ISLAND NUCLEAR GENERATING PLANT. UNIT NOS. 1 AND 2 DOCKET NOS. 50-282 AND 50-306 i
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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 j
subsequently published in the Federal Reaister on September 26, 1995, and i
became effective on October 26, 1995. The NRC added Option B, " Performance-Based Requirements," to allow licensees to voluntarily replace the i
prescriptive testing requirements of 10 CFR Part 50, Appendix J, with testing requirements based on both overall performance and the performance of j
individual components.
By application dated October 25, 1996, Northern States Power Company (the j
licensee) requested changes to the Technical Specifications (TS) for the i
Prairie Island Nuclear Generating Plant, Units 1 and 2.
The proposed changes 1
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 references Regulatory Guide 1.163, " Performance-Based Containment Leak-Test Program," dated September 1995, which specifies a method acceptable to the NRC for complying with Option B.
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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, does 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.
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.
10 CFR Part 50, Appendix J, " Primary Containment 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 9702240414 970219 PDR ADOCK 05000282 p
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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 Containment Leak-Test Program."
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Based on the results of this study, the staff developed a performance-based j
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 j
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 prescriptive testing requirements of Appendix J with j
testing requirements based on both overall and individual component leakage 1
rate performance.
1 Regulatory Guide 1.163 was developed as a method acceptable to the NRC staff i
for implementing Option B.
This regulatory guide states that the Nuclear i
Energy Institute (NEI) guidance document NEI 94-01, Rev. O, " Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J," provides methods acceptable to the NRC staff for complying with j
Option B with four exceptions which are described therein.
i Option B requires that Regulatory Guide 1.163 or another implementation document used by a licensee to develop a performance-based leakage testing srogram must be included, by general reference, in the plant TS. The licensee l
1as referenced Regulatory Guide 1.163 in the proposed Prairie Island TS.
a Regulatory Guide 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 i
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 j
extended up to 5 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 i
transmitted to NEI in a letter dated November 2,1995. These TS are to serve I
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 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 requirements.
Failure to meet an administrative limit requires the licensee to return to the minimum value of the test interval.
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Option B requires that the licensee maintain records to show that the criteria i
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 i
the individual components to show that the test intervals are adequate. These records are subject to NRC inspection, i
j 3.0 EVALUATION l
The licensee's October 25, 1996, letter to the NRC proposes to establish a
" Containment Leakage Rate Testing Program" and proposes to add this program to j
the TS. The program references Regulatory Guide 1.163, " Performance-Based Containment Leak Test Program," dated September 1995, which specifies methods acceptable to the NRC for complying with Option B.
This requires a change to existing TS 4.4.A and 4.4.C., and the addition of the " Containment Leakage Rate Testing Program" as Section 6.5.J.
Corresponding bases were also 3
j 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, i
The TS changes proposed by the licensee are in compliance with the i
requirements of Option B and consistent with the guidance of Regulatory Guide i
1.163. Further, despite the different format of the licensee's current TS, all of the important elements of the model TS guidance provided in the NRC l
1etter to NEI dated November 2, 1995, are included in the proposed TS.
However, the licensee has proposed several changes that deviate from those in
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the model TS, and those which are more than editorial are discussed below.
l The licensee has chosen to move the limits for secondary containment bypass leakage rates from the surveillance requirement portion of the TS to the i
program portion (TS 6.5.J.).
Since this is only a change in TS format and location and not a change in requirements, the staff finds it to be j
acceptable.
It should be noted that.the proposed TS set the Type C test interval for containment purge / vent valves to no more than 30 months. Although the model 3
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TS guidance provided in the NRC letter to NEI dated November 2, 1995, contains j-a requirement to perform leakage rate testing of containment purge valves every 6 months, the TS is in brackets, which means that it may or may not be j
applicable to a specific plant. The licensee's current TS do not contain a j
requirement for this more frequent leakage rate testing of containment j
purge / vent valves, which may be compared to the Appendix J, Option A frequency of once per refueling outage.
Further, Option B of Appendix J, Regulatory l
Guide 1.163, dated September 1995, and the subordinate guidance documents do not require the testing of these valves more often than once per 30 months.
1 Therefore, the proposed TS sets the test interval for containment purge / vent i
valves to no more than 30 months, through adherence to section C.2. of Regulatory Guide 1.163, dated September 1995. The staff finds this to be acceptable.
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Existing TS 4.4.C. requires the containment vacuum breakers to be Type C j
tested during each refueling outage. The licensee has proposed to include 1
these valves in the performance-based interval grouping, along with most of I
the other containment isolation valves, so that their test intervals could be i
increased to as much as 60 months, based on continued satisfactory performance. The vacuum breaker valves have an excellent leakage rate i
perfomance history, having never failed their administrative leakage limits in 10 years; in fact, leakage rate has never exceeded 17% of the limit in that 4
time. Also, no maintenance has been required on the valves' resilient seals in either unit since plant startup, and the licensee states that the seals are designed to last for 40 years.
Further, potential leakage through the vacuum 4
i breakers would go into the secondary containment, where it would be held up and filtered before release to the environment.
In consideration of the j
foregoing, the staff finds that the containment vacuum breaker valves may be put on a performance-based leakage rate testing interval, per the containment j
leakage rate testing program.
On February 10, 1997, the staff verified by telephone with the licensee and corrected a minor grammatical error on page B.4.4-2 to read "This provides assurance that the assumptions in the radiological evaluations of the safety i
analyses [are] met." The word "are" had been omitted.
1 In summary, the staff has reviewed the changes to the TS and associated Bases proposed by the licensee and finds that they are in compliance with the requirements of Appendix J, Option B, and consistent with the guidance of 4
l Regulatory Guide 1.163, dated September 1995, and are therefore acceptable.
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4.0 STATE CONSULTATION
i In accordance with the Commission's regulations, the Minnesota State official 3
was notified of the proposed issuance of the amendments. The State official had no comments.
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5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR i
Part 20 and change surveillance requirements. The NRC staff has determined that the amendments involve 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 amendments involve no significant hazards i
consideration and there has been no public comment on such finding i
(62 FR 2191). Accordingly, the amendments meet the eligibility criteria for j
categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR
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51.22(b), no environmental impact statement or environmental assessment need i
be prepared in connection with the issuance of the amendments.
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6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will 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.
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Principal Contributor:
J. Pulsipher Date:
February 19, 1997 l
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