NRC Generic Letter 80-35, Effect of a DC Power Supply Failure on ECCS Performances

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GL80035

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555

APRIL 25 1980

Docket No. 50-271

Mr. Robert L. Smith Licensing Enginer Vermont Yankee Nuclear Power Corporation 25 Research Drive Westboro, Massachusetts 01581

Dear Mr. Smith:

SUBJECT: EFFECT OF A DC POWER SUPPLY FAILURE ON ECCS PERFORMANCE

It has generally been recognized that the loss of a direct current (DC)

power supply could disable several emergency core cooling system components and thereby could result in a limiting single failure condition for some breaks. The enclosed letter report was submitted to the NRC staff by the General Electric Company to provide a definitive, generic, reference analysis of the effects of DC power supply failures on ECCS conformance calculations. The NRC staff is reviewing the analysis which compares the peak cladding temperatures associated with various postulated DC power supply failure (ECCS equipment availability) cases to the peak cladding temperatures for a HPCI (small break) failure and LPCI injection valve (large break) failure cases. Since the study was based on plant design information which may have been incomplete or out-of-date, some uncertainty exists whether the worse ECCS system availability combinations have been identified for your operating BWRs. Accordingly, in order that we may have an adequate level of assurance that the systems combinations assumed in the generic analysis are conservative for Vermont Yankee Nuclear Power Station, we request that you confirm the conclusion of the reference study regarding the minimum ECCS equipment availability with a DC power supply failure. Include in your response a list of the ECCS equipment that would be for large and small

(1) recirculation loop discharge breaks, and

(2) recirculation loop suction breaks. The listing of equipment available should take into account not only DC power supply failure, but also loss of equipment due to water spillage.

Please provide a schedule for your response within 30 days of the receipt of this letter.

.

Mr. Robert L. SmithAPRIL 25 1980

This request for generic information was approved by GAO under clearance number B-180225(579018); this clearance expires October 31, 1980.

Sincerely,

Thomas A. Ippolito, Chief Operating Reactors Branch #3 Division of Operating Reactors

Enclosure:

General Electric Company letter (R. E. Engle) to USNRC (P.S. Check), "DC Power Source Failure for BWR/3 and 4," dated November 1, 1978.

cc w/enclosure See next page

.

Mr. Robert L. SmithAPRIL 25 1990

cc:

Ms. J. M. Abbey Vermont Yankee Nuclear Power Corporation 77 Grove Street Rutland, Vermont 05701

Mr. Louis H. Heider, Vice President Vermont Yankee Nuclear Power Corporation 25 Research Drive Westboro, Massachusetts 01581

John A. Ritsher, Esquire Ropes & Gray 225 Franklin Street Boston, Massachusetts 02110

Laurie Burt Assistant Attorney, General Environmental Protection Division Attorney General's Office One Ashburton Place, 19th Floor Boston Massachusetts 02108

Ronald J. Wilson 810 18th Street, N. W. Suite 802 Washington, D. C. 20006

Honorable M. Jerome Diamond Attorney General State of Vermont 109 State Street Pavilion Office Building Montpelier, Vermont 05602

Mr. J. E. Griffin, President Vermont Yankee Nuclear Power Corporation 77 Grove Street Rutland, Vermont 05701

John R. Stanton, Director Radiation Control Agency Hazen Drive Concord, New Hampshire 03301

John W. Stevens Conservation Society of Southern Vermont P. O. Box 256 Townshend, Vermont 05353

.

Dr. Mars Longley, Director Occupational & Radiological Health 10 Baldwin Street Montpelier, Vermont 05602

New England Coalition on Nuclear Pollution Hill and Dale Farm West Hill - Faraway Road Putney, Vermont 05346

Public Service Board State of Vermont 120 State Street Montpelier, Vermont 05602

W. P. Murphy, Plant Superintendent Vermont Yankee Nuclear Power Corporation P. O. Box 157 Vernon, Vermont 05354

Mr. Charles Sheketoff Assistant Director Vermont Public Interest Research Group, Inc. 26 State Street Montpelier, Vermont 05602

Brooks Memorial Library 224 Main Street Brattleboro, Vermont 05301