ML20024J508
| ML20024J508 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/12/1994 |
| From: | Butler W Office of Nuclear Reactor Regulation |
| To: | NORTHEAST NUCLEAR ENERGY CO. |
| Shared Package | |
| ML20024J509 | List: |
| References | |
| NUDOCS 9410180365 | |
| Download: ML20024J508 (5) | |
Text
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7590-01 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of
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NORTHEAST NUCLEAR ENERGY COMPANY
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Docket No. 50-336
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(Millstone Nuclear Power Station,
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Unit No. 2)
EXEMPTION I.
The Northeast Nuclear Energy Company (NNEC0, the licensee) is the holder of facility Operating License No. DPR-65 which authorizes operation of Millstone Nuclear Power Station, Unit No. 2.
The license provides, among other things, that Millstone Unit 2 is subject to all rules, regulations, and Orders of the Commission now or hereafter in effect.
The plant is a pressurized water reactor located at the licensee's site in New London County, Connecticut.
II.
One of the conditions of all operating licenses for water-cooled power reactors, as specified in 10 CFR 50.54(o), is that primary reactor containments shall meet the containment leakage test requirements set forth in 10 CFR Part 50, Appendix J.
More specifically the following sections require that:
10 CFR Part 50. Accendix J.Section III.D.2(a)
Type B tests, except tests for air locks, shall be performed during reactor shutdown for refueling, or other convenient intervals, but in no case at intervals greater than 2 years.
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l 1 10 CFR Part 50. Accendix J.Section III.D.3 Type C tests shall be performed during each reactor shutdown for refueling but in no case at intervals greater than 2 years.
By letter dated September 26, 1994, NNEC0 requested schedular exemptions from the above requirements.
NNECO recently conducted a review of the Type B and Type C test data and on September 23, 1994, determined that a number of components, for which Type B and Type C testing is required, have exceeded their respective 24 month interval by up to approximately four months.
Previously, Millstone Unit 2 considered the Type B and Type C tests to constitute one group such that the 2-year surveillance window began after the last component test was completed during the refueling outage. A review of this rationale and discussions with industry counterparts and the NRC staff determined that this was not the appropriate interpretation.
Rather, each Type B or C test of a penetration or valve should be considered unique, each with its own 2-year surveillance window. Using the appropriate interpretation, NNEC0 determined on September 23, 1994, that a number of Type B and Type C tests have exceeded their required 24-month test interval by up to approximately 4 months.
The requirement to perform Type B and Type C local leak rate tests (LLRTs) on September 23, 1994, when NNEC0 discovered the misinterpretation of the requirement, would require an unscheduled plant shutdown, given the current Millstone Unit 2 refueling outage schedule. The total schedular delay in testing components will accumulate to be as much as 4 months before the plant is shutdown for refueling.
III.
By letter dated September 26, 1994, NNECO requested an exemption to the requirements of Section III.D.2(a) and III.D.3 which require that Type B and C testing be performed during each reactor shutdown for refueling but in no case
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, at intervals greater than 2 years.
In their submittal and in a phone conference between the staff and NNECO on September 24, 1994, NNECO stated that they recently conducted a review of the Type B and Type C test data and on September 23, 1994, determined that a number of components, for which Type B and Type C testing is required, have exceeded their respective 24-month interval by up to approximately 4 months. The previously refueling was l
lengthy (approximately 7 months) due the the replacement of both steam generators. The LLRTs during the outage, were conducted from June 1992 through December 1992.
Previously, NNECO considered the Type B and Type C tests to constitute one group such that the 2-year surveillance window began l
after the last component test was completed during the refueling outage. A review of this rationale and discussions with industry counterparts and the NRC staff determined that this was not the appropriate interpretation.
Rather, each Type B or C test of a penetration or valve should be considered unique, each with its own 2-year surveillance window.
Using the appropriate interpretation, NNECO determined on September 23, 1994, that a number of Type 8 and Type C tests have exceeded their required 24-month test interval by up to approximately 4 months. The requirement to perform Type B and Type C LLRTs on September 23, 1994, when NNEC0 discovered the misinterpretation of the requirement, would require an unscheduled plant shutdown, given the current Millstone Unit 2 refueling outage schedule. The total schedular delay in I
testing components will accumulate to be as much as 4 months before the plant is shutdown for refueling.
NNECO stated in their submittal that they had completed the second Type A test for the present 10-year service period successfully on December 24, 1992. The "As-Found" and "As-Left" integrated leakage rate test ILRT results were 0.2809 weight percent per day and 0.2577 weight percent per day
respectively.
Each ILRT result was below the Technical Specifications limit which demonstrates the overall leak-tightness of the containment.
In addition, as of December 1992, the total Type B and C "As-Found" and "As-Left" leakage results were 0.049 weight percent per day and 0.008 weight percent per day.
These values represent approximately 16.3% and 2.7% of the Technical Specification limit respectively. The results of these tests demonstrate that Millstone Unit 2 has maintained control of containment integrity by maintaining a conservative margin between the acceptance criterion and the "As-Found" and "As-Left" leakage rates. Subsequent to this ILRT, during Cycle 12, maintenance on several containment isolation valves was performed.
the post-maintenance retest requirements were accomplished by successful performance of Type C test. Thus, the previous Type A, B and C tests and prior post-maintenance retests of selected valves have demonstrated the leak-tightness of the containment and the reliability of the penetrations / valves.
Based 01, the above evaluation, the staff finds there is reasonable assurance tht: the containment leakage-limiting function will be maintained and that a forced outage to perform Type B and C tests ir not necessary.
Therefore, the staff finds the requested temporary exemption, to allow the Type B and C test intervals to be extended to the end of the 12th refueling outage which began on October 1,1994, to be acceptable.
IV.
Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12(a), the requested exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security. Further, the Commission finds that the special circumstances required by 10 CFR 50.12(a)(2)(ii,) are present. Application of
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., the regulation in these particular circumstances is not necessary.to achieve -
the underlying purpose of the rule in that, as discussed in Section III, the containment leakage-limiting function will be n:aintained.
An exemption is hereby granted from the requirements of Sections III.D.2(a) and III.D.3 of Appendix J to 10 CFR Part 50, which require that Type B and C tests be performed during each reactor shutdown for refueling but in no case at intervals greater than 2 years until end of the current refueling outage.
Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this Exemption will have no significant impact on the quality of the human environment (59 FR 50928).
This Exemption is effective upon issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Walter R. Butler, Acting Director Division of Reactor Projects - I/II i
Office of Nuclear Reactor Regulation
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Dated at Rockville, Maryland this 12th day of Ottober 1994.
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