ML20028E142

Interim Deficiency Rept Re Undetectable Failure Mode Which Could Exist in on-line Testing Circuits of Solid State Protection Sys.Initially Reported on 820805.Westinghouse Determining Design Alternatives.Next Rept by 830819

ML20028E142
Person / Time
Site:	Marble Hill
Issue date:	01/14/1983
From:	Shields S PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, 582-18, S82-18, SVP-0001-83, SVP-1-83, NUDOCS 8301210024
Download: ML20028E142 (2)

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i PUBLIC SERVICE INDIANA S. W. Shields Senior Vice President -

January 14, 1983 nuclear Division S82-18 SVP-0001-83 Mr. James G. Keppler, Docket Nos.:

STN 50-546 Regional Administrator STN 50-547 U. S. Nuclear Regulatory Commission Construction Permit Nos.:

Region III CPPR - 170 799 Roosevelt Road CPPR - 171 Glen Ellyn, Illinois 60137 Marble Hill Nuclear Generating Station - Units 1 and 2

Dear Mr. Keppler:

On August 5, 1982, Mr. T. D. Geib of Public Service Company of Indiana, Inc. (PSI) notified your office of a potentially reportable item as required by 10 CFR 50.55(e). Westinghouse identified an undetect able failure mode which could exist in on-line testing circuits for their Solid State Protection System (SSPS).

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 coil voltage from 120VAC to 15VDC during the test.

Subsequent tests from the Safeguards Test Cabinets energize each output relay to confirm actuation of the Safeguards device. In those instances where actuation of the final device would disrupt plant operation, a proving lamp verifies relay contact movement, field wiring, and electrical continuity through the final device.

As mentioned above, output relay coil continuity is confirmed without operating the relay by reducing the circuit voltage to 15VDC from 120VAC. Operation of the master relay by means of the pushbutton test switch also removes the shunt from the proving lamp and allows the 15VDC to energize the lamp to confirm continuity through the output relay coil.

8301210024 830114 PDR ADOCK 05000546 S

PDR JAN 171983 P. O. Box 190, New WaAington, Indiana 47162 812. 289.1000

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PUBUC SERVICE Letter:

J. G. Keppler January 14, 1983 S82-18 SVP-0001-83

.Upon completion of the master relay and output relay coil continuity tests, 120VAC circuit voltage is restored. However, if the switch contact which shunts the proving lamp should fail to reclose as expected and the system were called upon to operate, 120VAC would be applied to the proving lamp. Since plant operators would receive ao indication of the contact's failure to reclose, this situation might remain undetected. Depending on the output relay coil impedance and the number of output relays being operated by the master relay contacts, the current through the proving lamp could cause it to burn open before the output relays energized.

In such an instance, associated Safeguards devices in the affected train would not actuate. Westinghouse is reviewing this item to determine alternatives in design changes.

This letter is intended to fulfill the requirements of an interim report as required by 10 CFR 50.55(e). A further report will be filed on or before August-19,.1983. - If you have any questions regarding this matter please contact me at your convenience.

Sincerely, S. W. Shields SWS/LGY/bak cc: Director of Inspection and Enforcement U. S. Nuc1 car Regulatory C6mmission Washington, D. C.

20555 J. E. Konklin J. J. Harrison

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