ML19340A720
| ML19340A720 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/24/1977 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Bolger R COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8009030731 | |
| Download: ML19340A720 (9) | |
Text
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DISTRIBUTION Docket TBAbernathy NRC PDR JRBuchanan Local PDR AC'15 (16)
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Ccc onwealth Edison Company g y 04 1977 DLZiemann ATT;:: l4r. R. L. Bolger 7.ssistant Vice President MGrotenhuis P. O. Box 767 RMDjggs Chicago, Illinois 60690 r
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Gentlemen:
BBuckley DElsenut RE: DRESDE:1 TiUCLEAR POWER STATION LP IT 110. 1 Ue are reviewing your letter of Septe.ber 20, 1975, which referenced previous letters dated July 13, 1973 and September 19, 1973.
In your nost recent submittal you requested a number of specific exemptions fron the requirements of Appendix J to 10 CFR Part 50. To centinue our review of your request the additional information described in the enclosure is req 0 ired. To enable us te maintain our review schedule please submit the requested infomation within 60 days of the date of this letter.
Sincerely,
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. - =..n Dennis L. Ziemann, Chief Operating Reactors Cranch (2 Division of Operating Reactors
Enclosure:
Request for Additional Infomation cc w/ enclosure:
r. John U. Rowe Isha:.. Lincoln B Deale
': cur.selors at Law
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REQUEST FOR ADDITIONAL INFORMATION DRESDEN NUCLEAR POWER STATION UNIT NO. 1 DOCKET NO. 50-10 APPENDIX J REVIEW 1.
Testino of Instrument Lines You have requested an exemption from the requirements of paragraph II.H.1 of Appendix J as it relates to the Type C tests on the instrument lines.
Provide an evaluation to demonstrate that the Dresden Nuclear Power Station, Unit 1 is in accord with the Regulatory Positions set forth in Regulatory Guide 1.11, " Instrument Lines Penetrating Primary Reactor Containment" and " Supplement to Safet.' Guide 11, Instrument Lines Penetrating Reactor Containment Bac'< fitting Considera cions. "
( C c.s,- enclosed) 2.
Requested Exemotions for Type C Tests In. regard to paragraph II.H.2 of Appendix J to 10 CFR 50, we do not consider the statement in your September 26, 1975 letter, to be sufficient justification for the requested exemptions or an adequate response to our August 5, 1975 letter.
Provide the following additional information:
(a)
Identify all lines that penetrate the primary containment barrier; (b) for each penetration, describe the respective isolation valves, actuators and closure actuation signals; s
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(c) the leakage rate tests and time intervals between tests; (d) for all penetrations, including the above citad 17 lines, an identification and discussion of the design features that prevent conformance with the Appendix J 10 CFR 50 requirements or existing Technical Specifications require-ments; and (e) for all areas that are not in full compliance, identification of the planned actions and associated schedules to improve the degree of compliance with the regulations.
3.
Sequence of Local and Intearated Leak Rate Tests To satisfy paragraphs III.A.1.a and III.A.3.a of Appendix J to 10 CFR 50, you plan to conduct local leak rate tests during the first part of an outage and conduct an integrated leak rate test close to the end of the outage.
The requirements of Appendix J,10 CFR 50 and ANSI N45.4 with respect to the integrated leak rate test is that it be con-ducted following the required containment inspection and before any repairs or adjustments are made so as to provide assurance that the containment is tested in as close to the "as is" condi-tion as practical.
In regard to your plan to conduct local leak rate tests before the integrated leak rate test, we find that due to design considerations it is not possible to deterr.ine what portion of the total measured leakage was into the ccntainment and what portion was out of the containment.
Consequently, if the local leak rate tests are conducted before the integrated leak rate test, an element of uncertainty would exist as to the s
. method and its accuracy when correcting back to establish the "as is" integrated leak rate results.
If the total measured local leak rate is conservatively assumed to be out of the containment when making the correcting calculations to establish the "as it" integrated leak rate, we find the proposed approach acceptable.
If you should choose not to make the above assumption, we will require that the integrated leakage rate test be performed before any activities are carried out which would introduce additional uncertainties in the "as is" condition, such as local leak rate testing and repair.
Please indicate your intentici to abide by the Appendix J, 10 CFR 50 and K fi45.4 requirements or to accept the above described assumption in making the calculations to establishing the "as is" integrated leak rate.
4 Airlocks Your submittal describes the difficulties encountered in meeting the letter of the requirements of paragraph III.D.2, Appendix J regarding the periodic retest schedule of the airlock Type B tests, ana conciudes with the statement "Our experience k
. indicates trat testing at each refueling outage will satisfactorily ensure that the integrity of those locks is maintained."
We acknowledge that many operating plants had either received an operating license or were in advance stages of design or construc-tion when Appendix J to 10 CFR 50 was published on February 14, 1973.
Further, it is recognized that these plants will encounter difficulty in meeting tne letter of the requirements in the regulation.
Therefore, on a generic basis, we have developed positions which would enable such plants to satisfy the objective of the airlock testing require-cents.
It is our view that both the inner and outer airlock hatches are required to be tested at the accident pressure, pa, at six month intervals.
Further, an intermediate test will have to be conducted within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of the first of each series of openings that falls between each of the six moth periodic test intervals to demonstate that the door seals have properly reseated following airlock use.
These intermediate tests may be conducted at a reduced pressure, providing it is demonstrated that the leakage rate established at the reduced pressure can conservatively be extra-polated to tne leakage rate that will occur at accident pressure.
You may wish to consider the option of conducting the inter-mediate tests of the door seals at a reduced pressure and thereby tinimize the problems associated with testing at Pa.
The exe pticos that you have proposed, regarding the testing
. cf the airlocks, ar unacceptable.
To guide you in the preparation of an acceptable response, we have prepared a discussion of the Appendix J requirements, as they relate to airlock leakage testing, as described in Attachment A to this enclosure.
We will request that you submit a response within the range of options presented in Attachment A.
5.
Test Pressure for the Airlocks In regard to the airlock seal tests, paragraph II.G.2 specifies they are to be conducted as Type B tests and paragraph III.B.2 requires that the Type B test be made at a pressure not less than Pa, which is the calculated peak containment internal pressure re-lated to the design basis accident.
Provide a response, within the range of options presented in Attachment A, that utilizes the requested reduced oressure during the tests.
ATTACHMENT A C0pTAIN"ENTAIRLOCKS Appendix J to 10 CFR 50 requires that reactor contair. ment airlocks be leak tested at the peak calculated accident pressure (Pa) at six month intervals.
Further, should the airlocks be opened during such intervals, the airlocks will be leak tested after each opening.
Appendix J calls out these specific requirements for airlocks because they represent a potentially large leakage path that is more subject to human error than other isolation barriers.
The staff's interpretation of the objectives of the airlocks leak testing requirements are (1) that the six month test will provide an integrated leakage rate for the entire airlock assembly, including electrical and mechanical penetrations, the airlock cylinder, hinge assemblies, welded connections, and other potential leakage paths; and (2) that the "after each opening" test would provide a means of assur-ing that the door seals had not been damaged or seated improperly dur-ing airlock use.
For those operating facilities that were designed and constructed prior to the issuance of Appendix J, consideration has been given to the alternatives to the specific testing requirements which will meet the provisions of Appendix J.
Listed below are a number of guidelines which may be useful when considering or revising current airlock leak testing programs.
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At six month intervals, the entire airlock assembly shall be leak tested at the peak pressure, Pa.
If the test pressure will lift the inner airlock door off its seat a strongback or other mechanical devices should be used so that meaningful test results can be obtained at Pa.
2.
Should the airlock be opened during the interval between the six month tests, the airlock door seals shall be leak tested with in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of the first of a series of openings.
This relaxation in the "after each opening" test requirement of Appendix J recognizes that a significant amount of time is required to conduct these intermediate tests in relation to the frequency of use of the airlock. These tests would be conducted whenever containment integrity is required.
3.
For those plants which require the use of a strongback or clamps to leak' test the door seals at a pressure Pa, a lower pressure (e.g., manufacturer's recommended pressure, which would not require the use of such clampirg devices) should be used to conduct the intermediate tests. The results of leakage tests at the lower pressure shall be conservatively extrapolated to a leakage rate at the accident pressure Pa to determine acceptability.
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In lieu of the intermediate tests, an acceptable alternative would be the use of a continuous leakage monitoring system.
As in the case of reduced pressure intermediate tests it must be demonstrated that the leekage rate using a continuous pressurized monitoring system is sufficirntly sensitive, and can and will be conservatively extrapolated to the leakage rate that would be experienced under accident conditions (e.g., at a pressure of Pa).
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