ML20063L886

Interim Deficiency Rept Re Undetectable Failure in Solid State Protection Sys.Initially Reported on 820804. Recommended Revisions to Testing Procedures & Possible Design Changes Under Review.Next Rept Expected by 830303

ML20063L886
Person / Time
Site:	Wolf Creek, Callaway, 05000000
Issue date:	09/03/1982
From:	Petrick N STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM
To:	Jay Collins, James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, SLNRC-82-036, SLNRC-82-36, NUDOCS 8209090256
Download: ML20063L886 (2)

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EJ4UPPS Standardized Nuclear Unit Power Plant System 5 Choke Cherry Road Nicholas A. Petrick Rockville, Maryland 20850 Executive Director (301) 8694010

' September 3, 1982 SLNRC 82- 036 FILE: 0491.10.2 SUBJ: Interim Report: Undetectable Failure in Solid State Protection System; 10 CFR 50.55(e) Report 82-2 Mr. James G. Keppler Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 Mr. John T. Collins Administrator, Region IV U. S. Nuclear Regulatory Comnission Suite 1000, Parkway Central Plaza Arlington, Texas 76012 Docket Nos. STN 50-482 and STN 50-483

Reference:

Westinghouse (Rahe) letter, NS-EPR-2638, to NRC (DeYoung) 8/6/82.

Gentlemen:

On August 4,1982, SNUPPS informed the Nuclear Regulatory Commission Regions III and IV, of a potential deficiency involving an undetectable failure in the Solid State Protection System (SSPS). The infonnation was communicated by telephone to Mr. J. Konklin (Region III) and Mr. J.

Jaudon (Region IV) pursuant to 10CFR 50.55(e). The NRC was also informed of this issue on a generic basis by the referenced letter.

During review of a schematic diagram of the SSPS, Westinghouse discovered an undetectable f ailure which could exist in on-line testing circuits for relays in the system. Periodic testing of the SSPS includes actuation of master relays which actuate safety systems. Electrical continuity testing of the master relay and output relay coil involves reducing the circuit voltage from 120VAC to 15VDC, (to prevent actual operation of the relay),

by removing a shunt from the SSPS proving lamp. Upon test completion, 120VAC circuit voltage is restored. If the switch contacts which shunt the proving lamp should f ail to reclose as expected,120VAC would be applied to the lamp upon system actuation. The current through the lamp could cause it to burn open before the output relay (s) energized causing associated safety devices in the affected train not to actuate. Since it is a non-detectable failure, the identical f ailure in the redundant train must be assumed.

8209090256 820803 %P' 7 Ed2, DR ADOCK 05000

r SLNRC 82-Page 2.

The SNUPPS Utilities will review recommended revisions to testing proce-dures and possible design changes to correct this deficiency. Follow-up reports will keep the NRC informed regarding the actions taken by the SNUPPS Utilities relative to this matter. A followup. report will be submitted by March 3, 1983.

Very truly yours, hn -

Nicholas A. Petrick VAS/nid cc: G. L. Koester KGE D. T. McPhee KCPL D. F. Schnell UE T. H. Vandel NRC/WC J. Konklin NRC-Region III J. H. Neisler NRC/ CAL Record l

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