ML20147B766
| ML20147B766 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/11/1988 |
| From: | Varga S Office of Nuclear Reactor Regulation |
| To: | NORTHEAST NUCLEAR ENERGY CO. |
| Shared Package | |
| ML20147B710 | List: |
| References | |
| NUDOCS 8803020187 | |
| Download: ML20147B766 (5) | |
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7590-01 UN!iED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of i
NORTHEAST NUCLEAR ENERGY Docket No. 50-336 COMPANY. et.~al.
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(Millstone huclear Power Station
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Unit 2)
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EXEMPTION 1.
The Northeas+. Nuclear Energy Company, et al. (the licensee) is the holder of Facility Operat.ng License No. OPR-65, which authorizes operation of the Millstone Nuclear Power Staticn. Unit 2 (the facility) at steady-state power reactor core power levels not in excess of 2700 megawatts thermal. The license provides, among other things, that Millstone Unit No. 2 is subject to all the rules, regulations, and Orders of the Commission now or hereafter in effect.
The plant is a pressurized water reactor (PWR) located at the licensee's site in the town of Waterford. Connecticut.
11.
The Code of Federal P.egulations. 10 CFR 50.54(o), specifies that primary renctor containments for water-cooled power reactors shall comply with L
Appendix J. "Primary Reactor Containment Leakage Testing for Water-Cooled Poser Reactors." Paragraph Ill.A.3 of Appendix J incorporates by reference i
the American National Standard ANSI N45.4-1972. "Leakage Rate Testing of Containment Structures for Nuclear Reactors." This standard requires that 880307.0187 880211 PDR ADOCK 05000336 P
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2 containment leakage calculations for Containment Integrated Leakage Rate Tests (CILRTs) be performed using either the point-to-point method or total. time method.
A more recent standard, ANSI /ANS 56.8-1981, "Containment System Leakage Testing Requirements," which was intended to replace ANSI N45.4-1972, specifies the use of the mass point nethod to the exclusion of the two older methods.
The NRC staff anticipates publishing, for comment, a proposed revision to Appendix J that would permit the use of the mass point method. Pending such revision to Appendix J, licensees who wish to use the mass point technique must sutrit an application for partial exemption from the requirement that Apper. dix J test calculations for CILRTs will conform with ANSI N45.4-1972.
III.
By letter dated December 23, 1987, the licensee requested a partial exerption froni 10 CFR Part 50, Appendix J, Paragraph III.A.3, which requires that all CILRTs be perforwed in accordance with ANSI N45.4-1972, "Leakage Pate Testing of Containrent Structures for Nuclear Reactors."
ANSI N45.4-1972 requires that leakage calculations be perforn.ed using either the total time method or the point-to-point method. The licensee has stated in support of the application for exemption from Appendix J that the mass ppint method is a cert accurate rethcd of calculating containment leakage rate.
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f 3-It has been recognized by the professional community that the mass point method is superior to the two other rethods, point-to-point and total time, which are referenced in ANSI N45.4-1972 and endorsed by the present regulations.
The rnass point method calculates the air mass at each point in time, and plots it against tilne. A linear regression line is plotted through the mass-time points using a least square fit. The slope of this line is proportional to the leakage rate.
In addition to the method of calculation, consideration of the length of the test should also be included in the overall program.
In accordance with Section 7.6 of ANSI N45.a-1972, a test duration less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is only allcwed if approved by the NRC, and the only currently approved methodology for such a test is contained in Bechtel Topical Report BN-TOP-1, Revision 1, "Testing Criteria for Integrated Leakage Rate Testing of Primary Containment Structures for Nuclear Power Plants," dated November 1,1972. This approach only allows use of the total time method. Therefore, the staff will ccndition the exemption to require a miniinum test duration of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the mass point method is used.
The licensee's letter also submitted infors.ation to identify the special circumstances for granting this exemption for Millstone Unit No. 2 pursuant to 10 CFR 50.12. The purpose of Appendix J to 10 CFR Part 50 is to assure that containment leak-tight integrity can be verified periodically throughout the service lifetirre so as to maintain containnent leakage rate within the limit specified in the plait technical specifications. The underlying purpose of i
4 the rule specifying particular trethods for calculating leakage rates is to assure that accurate and conservative methods are used to assess the results of containment leakage rate tests. As set forth above, the mass point method has been a widely.used method providing accurate results and the staff has deternined that this method of calculating leakage rate satisfies the purpose of the rule.
Based on the above discussion, the licensee's proposed partial exenption from paragraph III.A.3 of Appendix J, to allow use of the mass point method as requested in the subtrittal dated December 23, 1987, is acceptable with the condition of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> minimum test duration. The exen,ption applies only to the nethod of calculating leakage rate (by use of the mass point method) and not to any other aspects of the tests.
IV.
Accordingly, the Contrission has detemined that, pursuant to 10 CFR 50.12, this exenption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with th.:onnon defense ar.d security, The Correissicn has further determined that special circumstances, as set ferth in 10 CFR 50.12(a)(2)(ii), are present justifying the exemption, namely that the application of the regulation in the particular circumstances is not necessary to achieve the underlying purpose of the rule. Accordingly, the Concission hereby grants an exenptien as described in Section III above from Faragraph III.A.3 ef Appendix il to the extent that the mass point rethod r.ay be used for centaintrent leakage rate calculations, provided it is used with a minimum test
. duration of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The exemption applies only to the method of calculating leakage rate (by use of the mass point method) and not any other aspects of the tests, Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this exempticn will have no significant impact on the environrert (53 FR 3801) '-
This exemption is effective upon issuance.
FCf THE NUCLEAR RI,i ATORY COMMISSION a',birept 01 vision of Reactor P Mjects-!/II Office of Nuclear Reactor Regulation Dated at Rockville Maryland this lith day of February 1988 1
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