ML20065R032

Significant Deficiency Rept SD 370/82-05 Re Problem W/Ssps on-line Testing Circuits.Initially Reported on 820920.Test Procedures Revised to Ensure Relay Test Circuits in Ssps Operate Properly

ML20065R032
Person / Time
Site:	Mcguire
Issue date:	10/20/1982
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, 50-370-82-45, SD-370-82-45, NUDOCS 8210290045
Download: ML20065R032 (3)

Text

e, 'e DUKE POWEn GOMPANY P.O. IM)X 33180 CilAHLOTTE. N.C. 28242 HAL15.TUCKEH TE LEPitONE ww.s reasso,,, (704) 373-4531 at= s.eae emenwernom October 20, 1982 Mr. James P, O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Re: McGuire Nuclear Station Unit 2 Docket No. 50-370

Dear Mr. O'Reilly:

Pursuant to 10 CFR 50.55e, please find attached Significant Deficiency Report SD 370/82-05 concerning a potential problem with the SSPS on-line testing circuits. Note that this SSPS undetectable failure was previously reported to the NRC by Westinghouse via Mr. E. P. Rahe'n (W/NTD Nuclear Safety) letter to Mr. R. DeYoung (NRC/0IE) d&ted August 6, 1982.

Very truly yours, f

Hal B. Tucker PBN/j fw Attachment cc: Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 i

Mr. P. R. Bemis Senior Resident Inspector-NRC McGuire Nuclear Station

{DFFICIAL copy 8210290045 B21020 PDR ADDCK 05000370 1E d[

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DUKE POWER COMPANY HCGUlRE NUCLEAR STATION SIGNIFICANT DEFICIENCY REPORT NUMBER: 50-370/82-05 REPORT DATE: October 20, 1982 FACILITY: McGuire Nuclear Station, Unit 2 IDENTIFICATION OF DEFICIENCY:

Potential with Solid State Protection System on-line testing circuits for failure to activate zhe safegrords systems due to possible failure of the switch contacts which shunt the proving lamp. Deficiency identified August 16, 1982 by Westinghouse (received August 23,1982).

INITIAL REPORT:

On September 20, 1982, A. Ignatonis, NRC Region II, Atlanta, Georgia was notified of the deficiency by W. O. Henry and J. E. Thomas of, Duke Power Company, Charlotte, North Carolina.

COMPONENT AND/OR SUPPLIER:

The component which could potentially fall is a test switch contact that is part of the Solid State Protection System manufactured by Westinghouse.

DESCRIPTION OF DEFICIENCY:

During review of a schematic diagram of the Solid State Protection System (SSPS), redrawn for purposes of consolidation, Westinghouse engineers uncovered an undetectable failure 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 Safeguards systems. When a preselected master relay is energized, a proving lamp in series with the output (slave) relay coil confirms electrical continuity. Operation of the relay is prevented by reducing the circuit voltage f rom 120 VAC to 15 VDC during test. Subsequent tests from the Safe-guards Test Cabinets energize (120 VAC) each output relay to confirm actuation of the Safeguards device. In those instances where actuation of the final device cannot be tolerated, a proving lamp in the Safeguards test circuits verifies relay contact movement, field wiring and electrical continuity through the final device. Operation of the master relay by means of the pushbutton test switch removes the shunt f rom the SSPS proving lamp and allows the 15 VDC to energize it confirming the continuity of the output relay coil.

Upon completion of the master relay and output relay coil continuity tests, 120'VAC ci rcuit voltage is restored. However, if the switch contacts which sh^unt the proving lamp should fail to reclose as expected, 120 VAC would be applied to the lamp in event the system were called upon to operate. Depend-ing on the output relay coil impedance and the number of output relays being cperated by the master relay contacts, the current through the lamp could cause it to burn open before the output relay (s) energized, in such an instance associated Safeguards devices in the affected train would not actuate.

7 Page 2 ANALYSIS OF SAFETY IMPLICATIONS:

Although failure of the subject test switch contacts is highly improbable, a test switch contact failure could cause associated safeguard devices in the affected train not to actuate.

CORRECTIVE ACTIONS:

A revision to test procedures conducted from the safeguards test cabinets I where operation of the SSPS output relays is verified has been made by Westinghouse to ensure the relay test circuits in the SSPS operated properly when the system is returned to its normal operating mode. Imple-mentation of this procedural revision will be completed prior to fuel load.

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