ML20052F207

Updated LER 81-060/03X-1:on 811020,determined Potential Exists to Reduce Number of Operable APRM & IRM Instrument Channels in Rod Block Trip Sys to Below Tech Spec Min

ML20052F207
Person / Time
Site:	Pilgrim
Issue date:	04/14/1982
From:	Whitney G BOSTON EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20052F191	List: ML20052F190 ML20052F207
References
LER-81-060-03X, LER-81-60-3X, NUDOCS 8205120230
Download: ML20052F207 (2)

Text

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[7fTTl lon october 20, 1981 a Failure and Malfunction Renore tanc funnoa which indicated that I g g ;,; positioning of the APRM bypass and IRM switches affects the Control Rod Withdrawal l

[ g l Block Instrumentation. The potential exists to reduce the number of operable APRM & l

g;y; , IRM instrument channels in an APRM & IRM Rod Block trip sys em to below the minimum l ya;gy l stipulated in Technical Specification (T.S.) Table 3.2.C. This situation is not indi-l oj,, lcative of an actual safety problem because the safety analyses do not take credit for l

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JJ 34 35 36 3/ 40 42 43 47 CAUSE DESCHIPTION AND CORRECTIVE ACTIONS h 11 101 IIncompatability of PNPS's ovinrInc hchnicn1 Specification for the Control Rod IJf th- l i t idrawal Block Instrumentation with an intended bypass function of the APRM'c 6 IRM's. I

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BOSTON EDISON COMPANY PILGFIM NUCLEAR PORER STATION

• DOCKET No. 50-293 Attachment to LER UPDATE 81-060/03X-1 Description As a result of an investigation conducted in response to a question raised by ,

the On-Site NSS representative, a Failure and Malfunction Report was issued on October 20, 1981 which indicated that the position of the APRM & IRM bypass switches affects the Control Rod Withdrawal Block Instrumentation.

The review indicated that the bypass switch has the potential to reduce the number of operable APRM & IRM instrument channels in an APRM & IRM rod block trip system to less than the minimum number of channels specified in.the Technical Specifications Table 3.2.C.

The situation is not indicative of an actual safety problem because the safety analyses do not take credit for APRM or IRM - initiated rod. blocks.

Cause and Corrective Action

. This condition exists because the Technical Specification requires that a minimum of two (2) APRM channels and three(3) IRM channels per trip system be operable,

. whereas, the trip bypass switches physically allow less than that number of instrument channels to exist. .

To ensure Te'chnical Specifications adherence until this problem is resolved,

" Caution Tags" have been placed on the APRM & IRM Bypass Switches.

To resolve this problem in the long term, a proposed Technical Specification change and/or logic change is being considered.

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