ML20151R867

Discusses Util Requesting Approval of Alternate Requirement Re Safety of Equipment in Main Steam Feedwater Isolation Areas.Util Proposal Unacceptable & Mod of FSAR to Reflect Stated Conclusions Requested

ML20151R867
Person / Time
Site:	Washington Public Power Supply System
Issue date:	04/21/1988
From:	Rubenstein L Office of Nuclear Reactor Regulation
To:	Mazur D WASHINGTON PUBLIC POWER SUPPLY SYSTEM
References
NUDOCS 8804280114
Download: ML20151R867 (4)

Text

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NUCLEAR REGULATORY COMMISSION t

g WASHINGTO N, D. C. 20555 O

l April 21, 1988 Docket No. STN 50-460 Mr. D. W. Mazur, Managing Director Washingten Public Power Supply System 3000 George Washington Way P. O. Box 968 Richland, Washington 99352

SUBJECT:

WPPSS NUCLEAR PROJECT 1 - MECHANISTIC FAILURES IN THE MAIN STEAM AND FEEDWATER ISOLATION AREA By letter dated October 1, 1986, you requested approval of an alternate requirement in lieu of that stated in Branch Technical Position (BTP) ASB 3-1 regarding the safety of equipment in the Main Steam and Feedwater Isolation Areas (MSFIA). The piping in these areas is commonly known as "superpipe,"

since they are designed under the break exclusion criteria of BTP MEB 3-1.

ipe The staff's criteria for protection against breaks in the superp(NUREG-0800, are set forth in BTP ASB 3-1, attached to Standard Review Plan Revision 1) Section 3.6.1, require postulating a non-mechanistic pipe break (longitudinal) with an area of at least one square foot at a location that has the greatest effect on essential equipment, including consideration of jet impingement effects. Prior to the issuance of NUREG-0800 in July 1981, the staff's criteria were set forth in BTP-APCSB 3-1 attached to SRP Section 3.6.1 of NUREG-75/087, and required that a non-mechanistic full flow area break be assumed to establish the design paramenters (i.e., pressure / temperature) of the enclosing protective structure.

Jet impingement and pi)e whip were not considered in these criteria. The latest revision to t1e criteria of BTP ASB 3-1, as noticed in the Federal Register, January 25, 1988, eliminated the need for consideration of jet impingement effects. However, the environmental effects from a one square foot break must still Le considered.

In lieu of the revised or original requirements in BT/ ASB 3-1, you have proposed to qualify the MSFIA and the internal essential equipment and components to withstand fluid releases from a four inch diameter steam line circunferential failure. Such a failure was stated to represent the most severe "mechanistically derived" break postulated within the MSFIA and is the design basis break for the MSFIA. You have also stated that due to the advanced stage of the construction of the MSFIA, it was not feasible at the time of the publication of NUREG-0800 to apply the revised criteria of BTP ASB 3-1 to the MSFIA design at WNP-1.

We have reviewed your proposal and do not find it acceptable. No basis has been provided for the postulation of the "mechanistic" circumferential pipe break, such as the smallest line in the MSFIA is a six inch diameter modulating steam dump line.. There is no indication that the safety margins of the HSFIA i

and the essential equipment are comparable to those which would be obtained under the criteria of BTP ASB 3-1, Revision 0, Revision 1, or the revision noticed in the Federal Register.

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i 2-Mr. D. W. llazur, Managing Director April 21, 1988 You will be required to qualify the MSFIA and essential equipment according to the criteria stated in the latest approved revision (least stringent) to SRP Section 3.6.1, BTP ASB 3-1 which deletes the requirement for protection against the effects of jet impingement in the break exclusion area. Therefore, jet impingement effects resulting from the postulated one square foot break need not be included in the qualification of the MSFIA and essential equipment at WNP-1. However, jet impingement effects from branch lines which have mechanistically postulated breaks in the break exclusion areas must still be considered in addition to the environmental effects from a one square foot break. You are requested to modify the FSAR to reflect the above conclusions.

Note that the staff does not consider this a backfit for WNP-1, as it is our understanding that during the construction permit stage of review, a full flow area break vts required to be considered (environmental effects only) at WNP-1.

Sincerely, L2 Lester S. Rubenstei rector Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, Y and Special Projects Office of Nuclear Reactor Regulation ec: See next page

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2 Mr. D. W. Mazur, Managing Director April 21, 1988 You will be required to qualify the MSFIA and essential equipment according to the criteria stated in the latest approved revision (least stringent) to SRP Section 3.6.1, BTP ASB 3-1 which deletes the requirement for protection against the effects of jet impingement in the break exclusion area. Therefore, jet impingement effects resulting from tM postulated one square foot break need not be included in the qualification of the MSFIA and essential equipment at WNP-1. However, jet impingement effects from branch lines which have mechanistically postulated breaks in the break exclusion areas must still be considered in addition to the environmental effects from a one square foot break. You are requested to modify the FSAR to reflect the above conclusions.

Note that the staff does not consider this a backfit for WNP-1, as it is our understanding that during the construction permit stage of review, a full flow area break was required to be considered (environmental effects only) at WNP-1.

Sincerely, Drfginni Signed By:

Lester S. Rubenstein, Director Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, Y and Special Projects Office of Nuclear Reactor Regulation cc: See next page Distribution:

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OFFICIAL RECORD COPY L

Mr. D. W. Mazur WPPSS Nuclear Project No. 1 Washington Public Power Supply System (WNP-1) Docket No. STN 50-460 cc:

Mr. Charles B. Brinkman Mr. G. C. Sorensen, Manager Washington Nuclear Operations Regulatory Programs Combustion Engineering, Inc.

Washington Public Power Supply 7010 Woodmont Avenue, Suite 1310 System Bethesda, Maryland 20814 Post Office Box 968 Richland, Washington 99352 Nicholas S. Reynolds Esq.

Bishop, Cook, Purcell & Reynolds Law Offices 1400 L. Street, N.W.

Washington, DC 20005-3502 G. E. Doupe, Esq.

Washington Public Power Supply System 3000 George Washington Way Richland, Washington 99352 Mr. Curtis Eschels, Chairman Energy Facility Site Evaluation Council Mail Stop PY-11 Olympia, Washington 98505 Mr. Douglas Coleman Washington Public Power Supply System P. O box 1223 Elma, Washington 98541 Mr. William Ang /WPPSS 3/5 Region Inspector l

U.S. Nuclear Regulatory Commission 1450 Maria Lane - Suite 210 Walnut Creek, California 94596 Mr. Eugene Rosolie Director Coalition for Safe Power 408 Southwest Second Avenue Portland, Oregon 97204 I

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