ML20136C291

Discusses Licensee Response to IE Bulletin 79-01 Re Stem Mounted Limiting Switches Unqualified for LOCA Environ. Outlines Conditions That Must Be Satisfied If Unqalified Limit Switches Are Not Replaced

ML20136C291
Person / Time
Site:	Browns Ferry
Issue date:	06/06/1979
From:	Lainas G Office of Nuclear Reactor Regulation
To:	Ippolito T Office of Nuclear Reactor Regulation
Shared Package
ML20136C288	List: ML20136C282 ML20136C291
References
NUDOCS 7909190033
Download: ML20136C291 (2)

Text

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• • "* M C 19*1 POCRANDLM FOR: T. Ippolito. Chief. Operating Reactors Branch #3 l

' Division of Operating Reactors FROM:

E. Lainas. Chief. Plant Systems Branch. Division of Operating Reactors l

l

SUBJECT:

BRobus FERRY L5IITS 1. 2 AND 3 - ENVIRONMENTAL QUALIFICATION OF STEAM POUNTED LIMIT SWITCHE5 WI M5 LIV's (IE BULLETIN 79-01)

J In connection with their response to IE Bulletin 79-01. TVA has reported l

that the stem ununted limit switches on the MSLIV's which provide input

' to the IF5 are not qualified for an accident (e.g. LOCA) environment.

(Ref. TVA letters dated February 23, 1979 and March 9,1979 and Telecon dated May 17. 1979). TVA has stated that these limit switches need not be environmentalTy qualified for an accident environment for the following reasons and, therefore, will not be replaced with qualified switches.

l l 1. The switches are not needed to mitigate any accident or transient including a fast closure of the M51V's. No credit has been taaen for these limit switches in the analyses provided in the FSAR.

2. The switches do not have any control function and are' isolated from all control circuits and the RPS by an interposing relay. l j

The only possible deleterious effect of a failure would be a loss

3. l of the position indication derived from the limit switches.

Me have reviewed the inforention provided by TVA and have concluded that the following conditions must be satisfied if the unqualified limit switches are not replaced.

1: An ar.alysis must be provided (or a reference if it has previously been provided) to show that the M5 LIV closure input to the P.p5 is not required to mitigate the consequences of a closure of three or more

• MSLIV's. Such an analysis does not appear to be included in the FSAR.

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2. Schematic diagrams must be provided which show all circuits with inputs from the unqualified limit switches and tfe interposing niey isolating the limit switches from the RPS so that we can verify that the switches do not have any(safety function and that they are adequately is from the'RPS. Note:

3. An environmentally qualified method of determining MSLIV position from the control roca sust be provided and the indication devices with input signals derived from the unqualified limit(1) switches must states that be should they clearly not identified with a pemanent tag which:

be relied en for position indication except during normal operation; and (2) provides a reference to an instrument located in the control room which she;1d be alied on .during transient or accident conditions.

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Please inform the licensee of our position and request that they provide the information identified above and make any modifications necessary to -

satisfy these conditions if they do not elect to mplace the unqualified limit switches.

G. Lainas. Chief Plant Systems Branch Division of Operating Reactors

Contact:

E. Butcher. X28077 cc: Y. Stello D. Eisenhut R. Vollmer P. Check R. Satterfield G. Lainas D. Tondi M. Chirumal l J. Burdoin

- R. Clark E. Butcher l

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