ML19347E287

LER 81-001/03L-0:on 810324,steam Generator Loop a Pressure Safeguards Actuation Setpoint Found Below Tech Spec.Caused by Setpoint Drift in Foxboro Model 63U-BC-OHCA-F Bistable. Bistable Replaced

ML19347E287
Person / Time
Site:	Point Beach
Issue date:	04/16/1981
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19347E285	List: ML19347E284 ML19347E287
References
LER-81-001-03L, LER-81-1-3L, NUDOCS 8104240524
Download: ML19347E287 (2)

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7 8 68 OOCKET NUMBER 89 EVENT DATE 74 75 EVENT OESC";iPTION %ND PRO 8ABLE CONSEQUENCES h 10 l 21 l On 0 3-24-81, during normal operation, periodic testing (reg. by Tech. l

O #3l l Spec. 15.4.5) revealed that a Unit 2 loop " A" SG pressure safeguards l l O 14 l l actuation setpoint was 3.96 percent below Tech. Spec. requirements l IO lsi i found in Table 15. 3.5-1. This is a 2-cf-3 logic initiating safety l lO is l l injection. Both the remaining channels were operable. The out-of-spec.l l 0 l 7 l l channel would have tripped at the lower setpoint. The event had no l 10181 i effect on the public health and safety as the 2 other channels were l 7 8 9 fully operational. M DE OE SU C E COMPONENT CODE SU8 DE SU E O 9 8

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42 43 44 47 CAUSE OESCRIPTION AND CORRECTIVE ACTIONS 27 l i 10 l l The event was caused by setpoint drif t in a Foxboro Model 6 3U-BC-OHCA-F l 3 i l bistable. The bistable was replaced. The bistable removed from i

, , l service was bench-tested and no specific cause for the setpoint drift i g l was identified. I LL1A l 1 - I 7 8 9 80 ST  % POWER OTHER STATUS Di O RY DISCOVERY DESCRIPTION li Is l W@ l ll 010l@l N/A l l B l@l Technician observation l ACTIVITY CO TENT RELEASED OPRELEASE AMOUNT OP ACTIVITY LOCATION OP RELEASE Ii is 'i LZ_J @' W@l N/A I IN/A l PERSONNEt ExPOSMES NuM8eR TvPE DES mPTiON @

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ATTACHMENT TO LICENSEE EVENT REPORT NO. 81-001/03L-0 Wisconsin Electric Power Company Point Beach Nuclear Plant Unit 2 Docket No. 50-301 During normal operation on March 24, 1981, pericdic testing (per the requirements of Technical Specification Section 15.4.5, plant procedure ICP 2.1) o f t' Unit 2 reactor protection and safeguards analog systems reveaJ',d that in one of the loop " A" steam generator pressure sare-guards channels, channel 482A, the actuation setpoint was 3.96 percent lower than that required by Technical Specification Table 15. 3. 5-1. Thus, generation of a safeguards actuation signal in channel 482A would have occurred at 480.2 psig, approximately 20 psig lower than the setpoint requirement of

>/=500 psig.

This is a two-out-of-three logic to cause safety injection. The other two channels were operable. All three channels would have tripped initiating the actuation signal although one channel was out-of-specification low.

The condition was caused by setpoint drift in a Foxboro Model 6 3U-BC-OHCA-F bistable unit. The bistable was replaced. The bistable removed from service was bench-tested and no specific cause of the setpoint drift was identified.

The event had no effect on the public health and safety as the two other channels were fully operational. The channel that had drifted would still have initiated the required signal, but at a lower level than required.

This event is being reported as required by Technical Specification 15. 6. 9. 2.B. l.

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