ML20236D232

Exemption from Requirements of 10CFR50,App J,Paragraph III.A.3, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors

ML20236D232
Person / Time
Site:	Millstone
Issue date:	10/15/1987
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	NORTHEAST NUCLEAR ENERGY CO.
Shared Package
ML20236D176	List: ML20236D173 ML20236D232 ML20236D298
References
NUDOCS 8710280080
Download: ML20236D232 (5)

Text

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7590-01 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the matter of ) Docket No. 50-245

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NORTHEAST NUCLEAR ENERGY )

COMPANY )

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(Millstone Nuclear Power Station, )

Unit Nc. 1) )

EXEMPTION I.

The Northeast Nuclear Energy Company (the Licensee) is the holder of Facility Operating License No. DPR-21 which authorizes the operation of the i

Millstone Nuclear Power Station Unit No. 1 (the facility) at steady state l reactor core power levels not in excess of 2011 megawatts thermal. The license provides, among other things, that Millstone Unit No. 1 is subject to all rules, regulations, and Orders of the Commission now or hereafter in effect.

The plant is a boiling water reactor (BWR) located at the licensee's site located in the town of Waterford, Connecticut.

II. i l

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l The Code of Federal Regulations,10 CFR 50.54(o), specifies that primary reactor containments for water-cooled power reactors shall comply with Appendix J, " Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors." Paragraph III.A.3 of Appendix J incorporates by reference the American National Standard Institute (ANSI) Standard N45.4-1972, " Leakage Rate Testing of Containment Structures for Nuclear Reactors." This standard 8710200080 871015 PDR P ADOCK 05000245 ppg

..e 7590-01 requires that 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," which was intended to replace ANSI N45.4-1972, specifies the use of the mass point method to the exclusion of the two older methods. A proposed revision to Appendix J, which has been published for public comment (51 FR 39538, dated October 29,1986), refersloaproposedRegulatoryGuide(MS021-5, October 1986), which endorses, with certain exceptions, the ANSI /ANS 56.8-1981 standard.

Pending approval of the revision to Appendix J, which would permit the mass point analysis, licensees who wish to use the mass point technique must submit an application for exemption from the requirement that Appendix J test calculations for CILRTs will conform with ANSI N45.4-1972.

III.

l By letter dated July 10, 1987, the licensee requested an exemption from l

10 CFR Part 50, Appendix J Paragraph III.A.3, which requires that all CILRTs be performed in accordance with ANSI N45.4-1972, " Leakage Rate Testing of Containment Structures for Nuclear Reactors." ANSI N45.4-1972 requires that leakage calculations be performed 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 point method is a more accurate method of calculating containment leakage.

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7590-01 )

It has been recognized by 'he t professional community that the mass point I method is superior to the two other methods, point-to-point and total time, which are referenced in ANSI N45.4-1972 and endorsed by the present regulations.

The mass point method calculates the air mass at each point in time, and plots it against time. A linear regression line is p. lotted through the mass-time

-points using a least square fit.- The slope of this line is the leakage rate.

Draft Regulatory Guide MS 021-5, which was published for comment in October 198E, endorses, with exceptions, the ANSI /ANS 56.8-1981 standard and the mass point method.

1 In addition to the method of calculation, consideration of the length of L the test should also be included in the overall program. In accordance with l l

Section 7.6 of ANSI N45.4-1972, 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 I allowed 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 l

l only allows use of the total time method. Therefore, the staff will condition 1

the exemption to require a minimum test duration of 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s:when the mass point method is used.

The licensee's letter also submitted information to identify the special circumstances for granting this exemption for Millstone Unit No.1 pursuant to 10 CFR 50.m.. 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 lifetime so as to maintain containment leakage within the limit ,

l specified in the plant technical specifications. The underlying purpose of n

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4- ' 7590-0'1 the rule specifying particular methods for calculating _ leakage ' rates is to -

assure that accurate and conservative methods are used to assess the re'sults of containment leak rate tests. As set forth above, the mass point method has been a widely used method providing accurate results and the staff.has' determined that this method of calculating leakage satisfies the purpose of the.. rule.

Based on the above discussion, the licensee's proposed exemption from paragraph Ill.A.3 of Appendix J, to allow use of the mass point method as requested in the submittal dated July 10,.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 /> minimu'm test duration, until such provision of Appendix J is modified. Thereafter, the licensee shall comply with the provisions of such rule (or may renew its request for exemption). The exemption applies only to the method of calculating leakage by use of the mass point method and-not to any other aspects of the tests.

. IV.

Accordingly, the Commission has determined that, pursuant to 10 CFR Part 50.12, this 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 securi ty. The Commission has further determined that special circumstances, assetforthin10CFR50.12(1)(2)(11), are present justifying the exemption, namely that application of the regulation in the particular circumstances is not necessary to achieve the underlying purpose of the rule. Accordingly,Lthe Commission hereby grants an exemption as described in in Section III above from Paragraph III. A.3 of Appendix J to the extent that the mass point method .

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.' j 7590-01 4

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. paragraph III.A 3 of Appendix J to the extent that-the Mass Point method may be used for containment 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 is granted until such provision of Appendix J is modified. Thereafter, the licensee shall comply with the provisions of such rule. The exemption applies only to the method of calculating leakage 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 exemption will have no significant impact on the environment (52 FR 38027 . 0ctober 13,1987).

This exemption is effective upon issuance.

FOR THE NUCLEAR REGULATORY COMMISSION A W.

ennis M. Crutchfield, rector Division of Reactor Pr ects III, IV, V and Special Projects Dated at Bethesda, Maryidnd this'15th day of October,1987