ML20126A769

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Environ Assessment & Finding of No Significant Impact Supporting Issuance of Exemption from Portion of Requirements of GDC 4
ML20126A769
Person / Time
Site: Millstone Dominion icon.png
Issue date: 05/21/1985
From: Knighton G
Office of Nuclear Reactor Regulation
To:
Shared Package
ML20126A771 List:
References
NUDOCS 8506130463
Download: ML20126A769 (4)


Text

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7590-01 UNITED STATES NUCLEAR 2EGULATORY COMMISSION NORTHEAST NUCLEAR ENERGY COMPANY DOCKET.NO.: 50-423 ENVIRONMENTAL ASSESSMENT AND FINDING OF NO SIGNIFICANT IMPACT The U. S. Nuclear Regulatory Commission (the Commission) is considering issuance of an Exemption from a portion of the reouirements of General Design

  • Criterion 4 (10 CFR 50, Appendix A) to the Northeast Nuclear Energy Company (the applicant) for the Millstone Nuclear Power Station, Unit 3, loc ted at the applicant's site in Waterford, Connecticut.

ENVIRONMENTAL ASSESSMENT:

Identification of Proposed Action:

The Exemption would permit the applicant not to consider dynamic loading effects associated with postulated pipe breaks in eight locations per loop in the Millstone Nuclear Power Station, Unit 3 primary coolant system on the basis of advanced calculational methods for assuring that piping stresses would not result in rapid piping failure; i.e.,

pipe breaks.

Noticed in the Federal Register on May 29, 1985 (50 FR 21954) 8506130463 850605 DR ADOCK 05000423 PDR j

7F90-01 Need for Proocsed Action:

The proposed exemption is needed in order to permit the applicants not to install protec.tive devices such as pipe whip restraints and jet shields related to 32 postulated break locations in the primary coolant icws. Analysis snows tr.at pipe breaks, which these oevices are cesigned to pro-tect against, will not occur. On the other hand the presence of these devices increases inservice inspection time in the containment and their elimination would tend to lessen the occupational doses to workers and facilitate inservice inspections. General Design Criterion (GDC) 4 requires that structures, systems anc componer.ts important to safety shall be appropriately protected against dynamic effects including the effects of discharging fluids that may result from equipment failures, up to and including a double-ended rupture of the largest pipe in the reactor coolant system (Definition of LOCA).

In recent submittals the applicant has provided information to show by advanced fracture mechanics techniques that the detection of small flaws by either inservice inspection or leakage monitoring systems is assured long before flaws in the piping materials can grow to critical or unstable sizes which could lead to large break areas such as the double-ended guillotine break or its equivalent.

The NRC staff has reviewed and accepted the applicant's conclusion. Therefore,

+he NRC staff agrees that censideration of the dynamic loading effects associated with a postulated double-ended guillotine break in the primary pressure coolant loop piping need not be reouired as a design basis accident for pipe protective devices and jet sheilds. Accordingly, the NRC staff agrees that an exemption from GDC 4 is appropriate, t

7590-01 Environrental Impact of the Proposed Action:

The proposed Exemption would not affect the environmental impact of the facility.

No credit is given for the restraints and barriers to be eliminated in calculating accident doses to the environment.

While the pipe whip restraints and jet impingement barriers would minimize the damage from jet forces and whipping from a broken pipe, the calculated limitation on stresses required to support this Exemption assures that the probability of pipe breaks which could give rise to such foreas are extremely small; thus, the pipe whip restraints and jet shields would have no significant effect on overall plant accident risk.

The Exemption does not otherwise affect radiological plant effluent.

Like-wise, the relief granted does not affect non-radiological plant effluents, and has no other environmental impact. The elimination of the pipe whip restraints and jet impingement shields would tend to lessen the occupational doses to workers inside containment. Therefore, the Commission concludes that there are no significant radiological or non-radiological impacts associated with this Exemption.

_ The proposed Exemption involves design features located entirely within the restricted area as defined in 10 CFR 20.

It does not affect plant non-radicactive effluents and has no other environmental impact.

Therefore, the Commission concludes that there are no non-radiolooical impacts associated with this proposed Exemption.

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7590-01 Since we have concluded that there are no measurable negative environ-mental impacts associated with this Exemption, any alternatives would not provide any significant additional protection of the environment. The alter-native to the compliance would be to require literal compliance with GDC 4.

Alternative Use of Resources:

This action does not involve the use of resources not previously considered in the Final Environmental Statement related to the-cperation of the Millstone Nuclear Power Station, Unit 3.

Acencies and Persons Contacted:

The NRC staff reviewed the applicant's request anc applicable documents referenced therein that support this Exemption for the Millstone Nuclear Power Station, Unit 3.

The NRC did not consult other agencies or persons.

FINDING 0F NO SIGNIFICANT IMPACT The Commission has determined not to prepare an environmental impact statement for this action.

Based upon the environmental assessment, we conclude that this action will not have a significant effect on the quality of the human environment.

Fcr details with respect to this action, see the reauest for exemption dated September 12, 1984 and additional information provided by the applicant in a letter dated October 18, 1964.

These documents, utilized in the NRC staff's technical evaluation of the exemption request, are available for public inspection at the Commission's Public Document Room, 1717 H Street,

)

a 7590-01 N. W., Washington, D. C., and at the Local Public Document Room at the Waterford Public Library, Rope Ferry Road, Route 156, Waterford, Connecticut. The staff's technical evaluation of the exemption request will be published with the exemp-tion and will also be available for inspect on at both locations listed above.

Dated at Bethesda, Maryland this.hdayof

,1985.

FOR THE NUCLEAR REGULATORY COMMISSION

/5 GeorgeW.Knightod,ActingAssistant Director for Licensing Division of Licensing DISTRIBUTION Docket File NRC PDR Local PDR PRC System NSIC

.LBf1 Rdg MRushbrook ELDoolittle-0 ELD, Attorney JKopeck TMNovak HThompson

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