ML20056H423

Environ Assessment & Finding of No Significant Impact Re Schedular Exemption from Requirements of 10CFR50 for Leakage Testing.Eis Unwarranted

ML20056H423
Person / Time
Site:	Dresden
Issue date:	08/26/1993
From:	Dyer J Office of Nuclear Reactor Regulation
To:
Shared Package
ML20056H424	List: ML20056H423
References
NUDOCS 9309090297
Download: ML20056H423 (5)

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~590-01 UNITED STATES NVCLEAR REGULATORY COMMISSION COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION. UNIT 3 1

l DOCKET NO. 50-249

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ENVIRONMENTAL ASSESSMENT AND FINDING 0F NO SIGNIFICANT IMPACT l

The U. S. Nuclear Regulatory Commission (the Commission) is considering issuance of a schedular exemption from the requirements of 10 CFR 50 to Commonwealth Edison Company (CECO, the licensee) for the Dresden Nuclear Power I

Station, Unit 3, located in Grundy County, Illinois.

ENVIRONMENTAL ASSESSMENT I

Identification of Proposed Action The proposed action would grant a schedular exemption from the l

requirements of Sections III.A.6(b), III.D.2(a), and III.D.3 (Type A, B, and type C tests, respectively) of Appendix J to 10 CF?. Part 50 relating to the primary reactor containment leakage testing for water cooled reactors. The purpose of the tests is to assure that leakage through primary reactor containment shall not exceed allowable leakage rate values as specified in the Technical Specifications and that periodic surveillance is performed.

The Need for the Proposed Action By letters dated May 14, 1993, as supplemented June 30, 1993, the licensee requested, pursuant to 10 CFR 50.12(a), a one-time schedular exemption for Dresden, Unit 3, from the local leak rate test intervals for certain type A, B, and C leak rate tests required by 10 CFR Part 50, Appendix J, Sections III.A.6(b), III.D.2(a), and III.D.3. The exemption is requested to support the current outage schedule and to avoid the potential i

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for an earlier reactor shutdown.

If a forced outage is imposed to perform testing, it would present undue hardship and cost in the form of increased i

i radiological exposure.

Furthermore, if a forced outage is imposed to perform the required testing, an additional plant shutdown and startup will be required.

In order to rectify these concerns, Ceco proposes to reschedule the Dresden, Unit 3, refuel outage from September 1993 to February 1994.

l Increasing the interval between refueling outages will cause Dresden, Unit 3, l

to exceed the Type A, B, and C leak rate testing surveillance intervals required for Type A, B, and C leak rate tests which can not be performed i

during reactor operation.

Environmental Imoacts of the Prooosed Action The proposed action includes exemptions from performing certain Type A, B, and C tests for a maximum period of 190 days beyond the required Appendix J test intervals.

As stated in 10 CFR Part 50, Appendix J, the purpose of the i

primary containment leak rate testing requirements is to ensure that leakage rates are maintained within the Technical Specification requirements and to assure that proper maintenance and repair is performed throughout the service j

i life of the containment boundary components. The requested exemption is i

consistent with the intent of 10 CFR 50.12(a), in that it represents a one-l time only schedular extension of short duration. The required leak tests will still be performed to assess compliance with Technical Specification requirements, albeit later, and to assure that any required maintenance or repair is performed. As noted in Sections III.A.6(b), III.D.2(a), and III.D.3 t

of Appendix J, it was intended that the testing be performed during refueling outages or other convenient intervals.

Extending the Appendix J intervals by a small amount to reach the next refueling outage will not significantly

' impact the integrity of the containment boundary and, therefore, will not c

significantly impact the consequences of an accident or transient in the unlikely event of such an occurrence during the 190 day extended period.

The exemption request is further supported by the information provided in the application. Ceco has identified those Type B and C volumes which will be leak tested during reactor operation.

In addition, Ceco has identified those volumes that will be leak tested should a forced outage of suitable duration occur prior to March 15, 1994 (190 day maximum exemption request).

These commitments reduce the number of volumes which need an exemption and the length of time for which an exemption would be required should a forced outage of sufficient duration occur.

Ceco has also provided the testing methodology which will be used if forced outages occur.

In order to provide an added margin of safety and to account for possible increases in the leakage rates of untested volumes during the relatively short period of the exemption, Dresden will impose an administrative limit for maximum pathway leakage of 80 percent of 0.6L, for the remaining Unit 3 fuel cycle.

Past Unit 3 local leak rate test data have, in general, demonstrated good leak rate test results. The current maximum pathway leakage rate for Dresden, Unit 3, as determined through Type B and C leak rate testing is 275.12 standard cubic feet per hour (scfh). This value is approximately 56 percent of the Technical Specification limit of 488.45 scfh (0.6L,).

In addition, the previous outace "As left" total minimum pathway leakage rate for Type B and C testable penetration was 145.71 scfh. This value is approximately 24 percent of the Technical Specification limit of 610.56 scfh (0. 75L,). By using the minimum pathway methodology, a conservative measurement of the actual leakage expected through a pathway under

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4 post-accident conditions can be determined. The previous outage "As Left" Integrated Leak Rate Test, completed on March 16, 1992, indicated that the primary containment overall integrated leakage rate, which obtains the summation of all potential leakage paths including containment welds, valves, fittings, and penetrations, was 0.6706 weight percent per day. This value is the sum of the 95% upper confidence limit calculated leak rate of 0.5546 weight percent per day plus the leakage rate of all nonvented pathways and the leakage compensation for the change in the drywell sump levels. This value is approximately 56 percent of the limit specified in the Technical Specifications (1.2 weight percent per day or 0.75 L,).

The above data, along with the station imposed limit for maximum pathway leakage, provide a basis for showing that the probability of exceeding the off a

site does rates established in 10 CFR 100 will not be increased by extending the current Type A, B, and C testing intervals for a maximum of 190 days. The l

proposed exemption does not affect plant nonradiological effluents and has no other environmental impact. Therefore, the Commission concludes there are no measurable environmental impacts associated with the proposed exemption.

Alternative to the Proposed Action Since the Commission has concluded there is no measurable environmental 4

impact associated with the proposed exemption, any alternatives with equal or greater environmental impact need not be evaluated. The principal alternative

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to the exemption would be to require rigid compliance with the requirements of Sections III.A.6(b), III.D.2(a), and III.D.3 of Appendix J to 10 CFR Part 50.

1 Such action would not enhance the protection of the environment and would l

result in unjustified costs for the licensee.

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Alternative Use of Retources This action does not involve the use of any resources not considered i

previously in the Final Environmental Statements for Dresden, Units 2 and 3, l

i dated November 1973.

Aaencies and Persons Consulted The staff consulted with the state of Illinois regarding the environmental impact of the proposed action. They had no comments.

FINDING 0F NO SIGNIFICANT IMPACT

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f The Commission has determined not to prepare an environmental impact statement for the proposed exemption.

t Based upon the foregoing environmental assessment, the NRC staff 1

concludes that the proposed action will not have a significant effect on the i

quality of the human environment.

For further details with respect to this proposed action, see the j

licensee's request for exemption da+2d May 14,1993, as supplemented June 30, l

1993, which is available for public inspection at the Commission's Public Document Room, the Gelman Building, 2120 L Street, N.W., Washington, D.C. and at the Morris Public Library, 604 Liberty Street, Morris, Illinois 60451.

Dated at Rockville, Maryland, this 26th day of August 1993.

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FOR THE NUCLEAR REGULATORY COMMISSION l

t Y-James E. Dyer, Director Project Directorate III-2 Division of Reactor Projects - III/IV/V Office of Nuclear Reactor Regulation t

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