ML20212Q212

Forwards Vermont Yankee Containment Safety Study, Per 860630 Commitment.Rept Represents 60-day Study Comparing Facility Design Features to Ref Plant in WASH-1400 & of Five Bernero BWR Containment Concerns

ML20212Q212
Person / Time
Site:	Vermont Yankee
Issue date:	09/02/1986
From:	Weigand J VERMONT YANKEE NUCLEAR POWER CORP.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20212Q214	List: ML20212Q212 ML20212Q273
References
NUDOCS 8609040082
Download: ML20212Q212 (2)

Text

VERMONT YANKEE NUCLEAR POWER CORPORATION I .

. RD 5. Box 169, Ferry Road, Brattleboro, VT 05301

$.V .

J. GAsv WOGAND PRESIDENT AND CHIEF E RECUTIVE OFFICER $eptember 2, }986 l 48an ts7-5271 Mr. Harold Denton Director, Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 1717 H Street, NW Washington, D.C. 20555

Reference:

Letter, J.G. Weigand to Mr. H. Denton, dated 6/30/86

Subject:

Vermont Yankee Containment Safety Study In accordance with our commitment contained in the reference letter, enclosed please find our completed Vermont Yankee Containment Safety Study.

This study represents an intensive 60 day effort on the part of Vermont Yankee and our consultants to compare Vermont Yankee design features to those of the reference plant in WASH-1400, calculate a Vermont Yankee specific con-tainment conditional failure probability, and address the five BWR containment concerns raised by Mr. Bernero last June.

Vermont Yankee has concluded that the best estimate of probability of con-tainment failure is once every 500,000 years, which corresponds to a 7 percent containment failure probability in the unlikely event of a serious accident resulting in core melt. The study does identify procedural enhancements and potential design modifications w:.;ch would enhance the Vermont Yankee contain-ment and make it even safer.

I We have already started efforts to implement procedure changes in areas where the study identified no competing safety concerns. These include pro-cedures for accommodating Station Blackout, for restoring ac power and for use of the diesel driven fire pump as motive power for drywell spray. We are also writing a guideline for venting. Numerous other procedural and design changes have been identified which warrant fuether study prior to implemen-tation. We are committed to improving the safety of our plant, and are already I initiating those follow-on studies which will lead to the implementation of improvements in containment safety.

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8609040082 860902 -

PDR ADOCK 05000271 A P PDR d-

VisitaloNT YANKlitt NUCI.IIAlt Powltit COltPOltATION U.S. Nuclear Regulatory Commission September 2, 1986 Page 2 l

Our quantification methodology is heavily dependent on applying the results of previous severe accident studies to Vermont Yankee specific design and opera-tional features. Our final report summarizes the results of this process, but does not provide a detailed description of each individual manipulation. We are willing to meet with your staff to answer any questions which may arise during your review.

We are looking forward to presenting this study to you and your staff on the afternoon of September lith.

Sincerely,

\ j I . .

_ea  %

I

/dm cc: Mr. D. Muller, w/15 enclosures Governor Kunin, w/ enclosure Commissioner Tarrant, w/3 enclosures Dr. T. Murley, Region I I

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