ML20072S461

Part 21 Rept Re Ssps semi-automatic Tester at Plant

ML20072S461
Person / Time
Site:	Beaver Valley
Issue date:	09/05/1994
From:	DUQUESNE LIGHT CO.
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20072S440	List: ML20072S438 ML20072S461
References
REF-PT21-94 NUDOCS 9409140087
Download: ML20072S461 (3)

Text

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Attachment 1 Page1 10 CFR Part 21 BVPS Unit No.1: Solid-State Protection System Semi-Automatic Tester (i) Name and Address ofIndividual Making Notification:

L. R. Freeland, General Manager, Nuclear Operations  !

Duquesne Light Company  :

Beaver Valley Power Station P.O. Box 4 i Shippingport, PA 15077 (ii) Basic Component AfTected: l l

Solid-State Protection System Semi-Automatic Tester / Clock-Counter Card l l

(iii) Firms Supplying Components:

Supplier: Westinghouse Electric Corp.

Energy Systems Business Unit Box 355 Pittsburgh, Pa 15230-0355 (iv) Nature of Defect:

i While performing routine on-line testing of the Train "B" Solid-State Protection System (SSPS) at BVPS Unit No.1, an anomaly with the SSPS semi-automatic tester was observed. The semi-automatic tester is used to generate test pulses to 1 check all possible input combinations to the universal logic card circuit. A recorder was used to check the test pulses generated by the semi-automatic tester.

This check revealed extra test pulses on Channel "A", such that all logic combinations were not being tested. Tester card Channel "A" produced a test pulse corresponding to each enable pulse produced by the clock-counter card (A103).

The extra pulses on Channel "A" could mask certain input logic combinations and a " good" test could be indicated even though all logic combinations were not individually verified. A failure in the universal logic card could go undetected as a result of this anomaly.

9409140087 940905i PDR ADOCK 05000334 S PDR.

Attachment 1 Page 2 10 CFR Part 21 BVPS Unit No.1: Solid-State Protection System Semi-Automatic Tester (Continued)

The SSPS is relied upon to mitigate the consequences of Condition II, III, and IV Faults as evaluated in the BVPS Unit No. I Updated Final Safety Analysis Report (UFSAR). Although the probabilities of an occurrence of an accident previously evaluated in the UFSAR are not significantly increased by the abnormality in the SSPS tester system, the functional deficiency in the coincidence logic scheme could result in protective actions occurring beyond the time frames identified in the UFSAR for accident mitigation. The redundancy of the SSPS could be lost given a scenario where the affected SSPS train is in service and the counterpart redundant train is assumed to be lost due to a single failure per the guidelines established in 10 CFR Part 21 and NUREG-0302 (Rev.1).

This anomaly in the SSPS semi-automatic tester could result in an unrecognized condition of unavailability of a train, which, in conjunction with a single failure of the opposite train could prevent a safety system from performing its accident mitigating functions. Therefore, a substantial safety hazard could be created as a result of this abnormality per the criteria of 10 CFR Part 21.

(v) Date on Which Defect Identified:

On July 5,1994, the problem was discovered during routine logic testing of the SSPS at BVPS Unit No.1. During trouble-shooting, it was determined that an anomaly existed with the SSPS semi-automatic tester.

(vi) Number and Location of Components:

Affected Components: Solid-State Protection System (SSPS)

Location: BVPS Unit No.1 Process Instrument Room

t Attachment 1 Page 3 l

10 CFR Part 21 i BVPS Unit No.1 -Solid-State Protection System Semi-Automatic Tester (Continued) l (vii) Corrective Actions Taken: I l

. The testing system clock-counter card (A103) was replaced and Train B SSPS l I output logic was successfully tested. The opposite train (Train A) SSPS output logic was tested, utilizing a recorder to verify proper logic l combinations, and found to be satisfactory.

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. The Unit No. 2 SSPS, which utilizes the same type semi-automatic tester system, was also checked and found to have no abnormalities.

. The original defective clock-counter card (A103) was sent to Westinghouse l

for evaluation. Westinghouse is currently investigating the problem and is j presently considering issuing a Nuclear Safety Advisory Letter to advise the j l mdustry of this potential problem. i i .

. Duquesne Light Company initiated an INPO NUCLEAR NETWORK message l l to notify other licensees of this potential anomaly with the SSPS semi- l automatic tester. l l

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