ML20149J818
| ML20149J818 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 02/17/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20149J750 | List: |
| References | |
| NUDOCS 8802230228 | |
| Download: ML20149J818 (4) | |
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- o, UNITED STATES I'
NUCLEAR REGULATORY COMMIMION i
f WASHINGTON D. C. 2eHS I
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SAFETY EVALUATION BY THE OFFICE OF hbCLEAR REACTOR REGULATION l
t RE'.ATED TO APPENDIX J EXEMPTION REQUESTS l
l AND AMENCHENT h0. 116 TO FACILITY LICENSE NO. DPR-71 1
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AND AMENDNENT NO. 144 TO FACILITY LICENSE NO. OPb,62, CAROLINA POWER & LIGHT CCMFANY BRUNSWICK STEAM ELECTRIC PLANT, UNIT 1 AND 2 I
EK,Elh05.50-325AND50-324 1.0 INTROCUCTION By letter dated August 5,1987, the licensee requested an e4er ption from 10 CFR Part 50, Aposndix J. Paragraph !!!.A.3, which requires that.111 l
Containment Integrated Li:akage Rate Tests (CILRTs) be perfonned in l
accordance with the American National Standard Institute (ANSI)
N45.4-1972, "Leakage Rate Testing of Contaireent Structures for Nuclear i
Reactcrs." ANSI h45.4-1972 requires that leakage rate calculations be performed using either the Total Time method or the Point to Point method.
The licensee's requesteo exemption would allow use of the Mass-Point Mthod j
to calculate containment leakag/Ah5 56.0-1981, "Centaina nt System L e rate.
The Mass-Point m thod is described I
in a more recent standard, ANSI Testing Requirements." Also included in the licensee's uteittal was a re-i quest to change the Technical Sovcifications (TS), specifically surveillance l
requirernent 4.6.1.2 and the associated bases. The changes are neeced for cor.ststency be St.en App 2nc1x J and the TS.
The staf t's review of this i
request for exemption and amendment follows.
2.0 EVALUATION The licensee indicated that in 1976 the hRC staff urofficially recogni:cd the merits of the Mass-Point technique and that this method was the recomended method to use. On this basis, the licensee has perfonneo calculations using the Mass. Point method.
The licensee was recently inforu d by the staff that, with regard to the Mass-Point u thod, this M thod has not been incorporated into the current provisions of l
10 CFR Part 50 Appendix J, anc, therefore, its use requires an i
exemption.
In response to this staff position, the licensee has requested an Appendix J exemptien.
The licensee has stated, in support of the application for axemption from AppendtA J, that the Mass Point method is a rore accurate methud of calculating containmot leakage.
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The Pass-Point aethod has been recognized by th[ professional connunity aa superior to the two other methods, Point-tc-Point and Total Tl'ie, which are referenced in AllSI N45.4-1972 and endorned by the present regulations.
The Nss-Point trethod calculates the air mass at each point in tire, and plots it against time. A linear regression line is plotted thrcugh the e. ass-time points using a least square fit.
The slope of this line, civided Ly its intercept and multipibd by an appropriate constant, is the leakage rate.
The superiority of the Mass-Point swthod becores apparent when it is compared with the other methods. With the Total Time methed, a series of leakage rates are calculated on the basis of air mass dif ferent.es between an initial datum point and each individud datum point thereafter.
If for any reason (e,q instrument error, lack o. temperature equilibrium, ingassing, or outgassing), the initial datum point is not accurate, the results of the test will be affected.
In +.be Point-to-Point method, the leak rates are based on tha mass difference between each pair of consecutive points which are then averaged to yield a single leakage rate estimate. Fathematically this can be shown to ce the difference between the sir F. ass at the beginning of the test and the air mass at the end of thu test, expressed as a percentage of the containment air mass.
It fellcws from the above that the Point-to-Pcint rethod ignores any mass readings taken during the test; and, thus, the leakage rate is calculated on the basis of the difference in mass between two measurements taken et the beginning and at the end of the test, which are 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> apart.
ANSI /ANS E6.8-1981, which was intended to replace AM;I N45.4-1972, specifies the use of the Mass-Point method, to the exclusion of the two older methods.
The staff antidpates publishing for comment in the near future a proposed amendment to Appendu J that would permit the use of the Mass-Point method.
In addition to the method of calculation, consideration of the length of j
the test should also be included la the overall program In accordance i
with Section 1.6 of ANSI N45.4-1972, a test duration less than 24 nours i
is cnly allo,ed if approved by the NRC staff, and the only currently approved rethodology for such a test is contained in Bechtel Topical
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Report BN-TOP-1, Revisien 1, "Testing Criteria for Integrated Leekage Rate Ter. ting of Primary Containrent Structures for huclear Power Plants,"
I dated November 1,1972. This approach only allows use of the Tctal Time method. Therefore, the staff will condition the exertption to require 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 /> when the Mass-Foint nethod is used.
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O Infomatit.m identifying the special circumstances for granting this exemption pursuant to 10 CFR 50.12 was also provided in the licensee's letter.
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 in order to maintain containment leakage within the limit specified in the facility TS.
The underlying purpose of the rule.
in specifying particular methods for calculating leakage rates, is to assure that accurate and conservative methods are used to assess the results of containment leak rate tests.
The staff has deternined that 1
the Mass Point rathod is an acceptable method for calculation of containment leakage rate and satisfies the purpose of the rule.
3.0 ENVIROWENTAL CONSIDERATION This atendment involves a change in surveillance requirements.
The i
staff has detemined that the arendment involves no significant I
increase in the arcunts, and r.o significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiatien exposure.
The Comission has previously issued a proposed finding that this amendrent involves no significant hazards consideration, and there has been no public coment on such finding.
Accordingly, this amendrent rNtets the eligibility) criteria for categorical exclusion set forth in 10 CFR 51.22(c (9).
Pursuant to 10 CFR 51.22(b), no environmental impact staterent or envirenrental assessrent need be prepared in connection with the issuance of this arendront.
4.0 CONCLUSION
Based on the above evaluatien, the Commission's staff finds that the licsnsee's proposed exemption fron 10 CFR Part 50. Paragraph !!!.A.3 of i
Aprendix J, to allow use of the Mass-Point rathod as requested in the submittal dated August 5,1987, is acceptable with the condition that the minirum test duration is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The eserption applies only to the method of calculating leakage by use of the Pass-Point rethod and not to any other aspects of the tests.
The Comission rade a proposed detemination that the amendrent involves I
ro significant hazards consideration, which was published in the Federal i
_ Register on December 16. 1987 at 52 FR 47776 and consulted with the State of North Carolina.
No public ccerents or requests for tearing were received and the State of horth Carolina old not have any coments.
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The staff has concluded, based en the consideration discussed above, that:
(1) there is reaterable assurarce that +>e health and safety of the public will not be erdancerad by operation ir the proposed manner, and (?) such activities will be conducted in compliance with the Commission's regulations and +ba issusnee of this amerdrent will not be inimical to the common eeferse and the security eer to tha herith and safety of the publir.
Principal Cc9tribu+ ors:
B. Morafari,i'. Pultipher l
Dated: February 17, 198S 1
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