ML19270G988

Forwards Analysis of Complete Loss of Feedwater Transient for Facility, in Response to Request for Study of Reliability of Auxiliary Feedwater Sys

ML19270G988
Person / Time
Site:	Davis Besse
Issue date:	06/15/1979
From:	Roe L TOLEDO EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
TAC-43516, NUDOCS 7906220298
Download: ML19270G988 (21)

Text

Docket No. 50-346 License No. NPF-3 Serial No. 517 June 15, 1979 TCLECO EDISDN Mr. Harold R. Denton, Director LCWELL E. RCE Office of Nuclear Reactor Regulation vice wn.e.a.

U. S. Nuclear Regulatory Commission " * " " ' ' '

Washington, D. C. 20555

Dear Mr. Denton:

The Davis-Besse Nuclear Power Station Unit 1 has a full safety grade auxiliary feedwater system which includes the initiating and steam generator level control system, feedwater pumps and steam turbine drives, and the necessary steam and feedwater piping including certain cross-feed and steam supply capability. This system fully meets the single failure criteria and is completely independent of the Integrated Control System (ICS) and other non-safety related control systems.

Reliability improvements have been made to the auxiliary feedwater system result-ting from startup experience and have been submitted for your staff's review.

Inherent design features at Davis-Besse include a raised loop reactor primary coolant system that has been demonstrated to give greater time for operator actions than any other Babcock & Wilcox facility to handle off normal feedwater interruptions.

Additionally, the ability of the steam generator to maintain pressure for pump turbine operation over aa extended time has been experienced. All these factors reinforce the acceptability of the current response capability of the Davis-Besse auxiliary feedwater system.

However, in my letter of April 27, 1979 and in the Commission's Order of May 16, 1979, there was a commitment and requirement that we, on a long term basis, continue to study the reliability of the auxiliary feedwater system for the Davis-Besse Unit 1.

As part of this commitment and requirement, even though there is an extremely low probability that there would be no auxiliary feedwater available if called for, we have asked B&W to conduct a review and analysis of the consequences of no auxiliary feedwater being available. We have also considered what systems

ther than auxiliary feedwater are available to mitigate the consequences of loss of auxiliary feedwater and permit uninterrupted cooling of the reactor core.

You and your staff have been made aware of this effort and a portion of the pre-liminary results to date were discussed with the review team during the site visit on June 8, 1979. As a result of these and other discussions you have also requested the results of this study to be submitted.

We, accordingly, have prepared this in a formal report and are enclosing five copies of the " Analysis of A Complete I,oss of Feedwater Transient for the Davis-Besse Nuclear Power Station, Unit 1".

Yours very truly, cc: Guy Vissing Operating Reactors Branch No. 4

. o-R. Division of Operating Reactors U.S. Nuclear Regulatory Commission MRm Washington, D. C. 20555 Enclosure THE TCLECO EDISCN COMPANY EDISON PLAZA 3C0 MACISCN AVENUE TCLECC. CMC 43552 9\0

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