ML20077Q675
| ML20077Q675 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/13/1995 |
| From: | Roe J Office of Nuclear Reactor Regulation |
| To: | COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML20077Q680 | List: |
| References | |
| NUDOCS 9501190313 | |
| Download: ML20077Q675 (5) | |
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'g UNITED STATES OF AMERICA NUCLEAR REGULATORY COMISSION In the matter of
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COMONWEALTH EDISON COMPANY
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Docket No. 50-237
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(Dresden Nuclear Power Station,
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Unit 2)
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EXEMPTION I.
Commonwealth Edison Company (Comed, the licensee) is the holder of Facility Operating License No. DPR-19, which authorizes operation of the Dresden Nuclear Power Station, Unit 2 (the facility), at a steady-state power level not in excess of 2527 megawatts thermal. The facility is a boiling watar reactor located at the licensee's site in Grundy County, Illinois. This license provides, among other things, that the facility is subject to all rules, regulations, and Orders of the U. S. Nuclear Regulatory Commission (the Commission) now av hereafter in effect.
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II.
By letter dated November 23, 1994, pursuant to 10 CFR 50.12(a), Comed requested a schedular exemption for Dresden, Unit 2, from the 24-month test interval for the Type B and C local leak rate test (LLRT) as required by j
10 CFR Part 50, Appendix J, Sections III.D.2(a) and III.D.3. The exemption is requested to avoid a potential reactor shut down to perform the Type B and C tests.
Due to two forced outages, Comed has had to reschedule the Dresden, I
l Unit 2, refueling outage from February 1995 to July 1995. Subsequently, Comed
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requested a maximum extension of up to an additional 180 days for the most extreme case, from performing the Type B and C testing. The Type B and C tests cannot be performed during power operation.
III.
In its letter dated November 23, 1994, Comed requested a one-time exemption from the 24-month Type B and C test interval requirements of Appendix J for certain volumes (i.e., bellows, manway gasket seals, flanges, I
and isolation valves) identified in Attachment III of the licensee's submittal. Comed stated that these volumes cannot be tested while the reactor is at power and provided the basis for this conclusion in Attachment IV of their submittal.
The licensee provided leakage test results and maintenance information on these volumes for the past two refueling outages. The current maximum o
pathway leakage rate for Dresden, Unit'2, as determined through Type B and C leak rate. testing, is 309.46 standard cubic feet per hour (scfh). This value is approximately 63 percent of the Technical Specification (TS) limit of 488.45 scfh (0.6L,).
In addition, the previous outage "as left" total minimum
- pathway leakage rate for Type B and C testable penetrations was 173.25 scfh.
The Type A integrated leak rate test, which obtains the summation of all potential leakage paths (including containment welds, valves, fittings, and penetrations) was performed on May 14, 1993. The resulting leakage from the test was 493.36 scfh. This value is approximately 80.8 percent of the limit specified in the TS (0.75 L ).
In order to provide an added margin of safety and to account for possible increases in the leakage rates of untested volumes during the I
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l 3-relatively short period of the exemption, Dresden Nuclear Power Station, Unit 2, will impose an administrative limit for maximum pathway leakage of 80 percent of 0.6L, for the remaining Unit 2 fuel cycle.
l To reduce the number of volumes which need an exemption, Comed will test j
the volumes listed in Attachment V of their submittal during reactor l
operation.
In addition, volumes listed in Attachment III of their submittal will be tested should a forced outage of suitable duration occur prior to July 16, 1995.
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The staff has reviewed Comed's submittal regarding the Appendix J test
. interval exemption request.
In summary, the staff finds that, for the specific volumes listed in Attachment III of Comed's submittal, extending the i
schedule for the required Type B and C tests by 180 days will not affect containment integrity based on the following:
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Testing has shown low "as found" leakage during the past two i
outages. The ample margin between the measured leakage and the allowable i
i leakage should accommodate any degradation likely to be experienced for these components during the extended period.
2.
The intent of Appendix J was that Type B. and C testing be performed during a refueling outage.
It is not the intent of Appendix J to require a shutdown solely for surveillance testing. The exemption would provide relief from the requirements of Appendix J to allow a test interval extension for these components which only became necessary as a result of rescheduling the Unit 2, Cycle 14, refueling outage.
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- Based on the above discussion, the staff finds that for the component volumes identified in Attachment III of Comed's submittal, an exemption from the LLRT test frequency specified in Appendix J should be granted.
IV.
Based on the above, the staff concludes that the licensee's proposed extension of the test intervals for test components identified in its submittal is acceptable. This is a one-time exemption from the Type B and C test interval requirements as prescribed in Appendix J, and is intended to be in effect until July 16, 1995. This approval is based on the assumption that all other tests will be conducted in accordance with the requirements of l
Appendix J.
l The Commission's regulations at 10 CFR 50.12 provide that special l
I circumstances must be present in order for an exemption from the regulations to be granted. According to 10 CFR 50.12(a)(2)(ii), special circumstances are present whenever application of the regulation in the particular circumstances would not serve the underlying purpose of the rule or is not necessary to achieve the underlying purpose of the rule. The underlying purpose of the requirement to perform Type B and Type C containment leak rate tests at intervals not to exceed 2 years, is to ensure that any potential leakage pathways through the containment boundary are identified within a time span that prevents significant degradation from continuing or being unknown, and long enough to allow the tests to be conducted during scheduled refueling outages. This interval was originally published in Appendix J when refueling cycles were conducted at approximately annual intervals and has not been changed to reflect 18-month or 2-year operating cycles.
It is not the intent i
e ni of the regulation to require a plant shutdown, solely for the purpose of conducting the periodic leak rate tests. As Indicated above, based on past local leakage rate testing data, the 180-day extension of the test interval will not affect the performance of the containment. To require a shutdcwn solely for surveillance testing would not serve the underlying purpose of the rule.
Accordingly, the Commission has determined, pursuant to 10 CFR 50.12(a),
that this exemption is authorized by law and will not present an undue risk to the public health and safety, and is consistent with the common defense and security.
In addition, the Commission has found special circumstances in that application of the regulation in these particular circumstances would not serve the underlying purpose of the rule. Therefore, the Commission hereby grants the exemption from 10 CFR Part 50, Appendix J, Sections III.D.2(a) and III.D.3 to the extent that the Appendix J test interval for performing Type B tests (except for air locks) and Type C tests may be extended for 180 days until July 16, 1995, on a one-time only basis, for Dresden, Unit 2, as described in Section III above.
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 (60 FR3277).
FOR THE NUCLEAR REGULATORY COMMISSION ack W. Roe, Director Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation i
Dated at Rockville, Maryland this 13th day of January 1995 i