05000395/LER-1983-036, Forwards LER 83-036/03L-0.Detailed Event Analysis Encl

Forwards LER 83-036/03L-0.Detailed Event Analysis Encl

ML20023D449
Person / Time
Site:	Summer
Issue date:	05/13/1983
From:	Dixon O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20023D450	List: 05000395/LER-1983-036, Forwards LER 83-036/03L-0.Detailed Event Analysis Encl 05000395/LER-1983-036-03, /03L-0:on 830414,during Performance of Channel Calibr,Pressurizer Safety Valve Position Indication on Valves Failed to Function Properly.Caused by Excessive Current Flow During Contact Closure.Switch Assembly Changed
References
NUDOCS 8305200510
Download: ML20023D449 (3)

LER-1983-036, Forwards LER 83-036/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3951983036R00 - NRC Website

text

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SOUTH CAROLINA ELECTRIC & GAS COMPANY co Post orrict 7s4 w

CoLuMalA. SOUTH CAROUNA 29218 g

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y.r O. W. Dixon. JR.

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VICE PRESIDENT P3y 13, 1983 2,

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$f Mr. James P. O'Reilly C3 q~

Regional Administrator U.S. Nuclear Regulatory Commission Region II, Suite 2900 101 Marietta Street, N.W.

Atlanta, Georgia 30303

SUBJECT:

Virgil C. Summer Nuclear Station Cocket No. 50/395 Operating License No. NPF-12 Thirty Day Written Report LER 83-036

Dear Mr. O'Reilly:

Please find attached Licensee Event Report #83-036 for Virgil C.

Summer Nuclear Station.

This Thirty Day Report is required by Technical Specification 6.9.1.13.(b) as a result of discovering an inoperable condition of the Pressurizer Safety Valve Position Indication on April 14, 1983.

This indication is required by Technical Specification 3.3.3.6, " Accident Monitoring Instrumentation," to ha operable in Modes 1, 2,

and 3.

This condition was discovered with the plant operating in Mode 5.

. Should there be any questions, please call us at your convenience.

Very tr ly yours, Tf( )

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i O. W.

ix r Jr.

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J. Braddick cc:

V. C.

Summer l

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C. Nichols, Jr.,/O.

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Dixon, Jr.

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Miller E.

C. Roberts J. L.

Skolds J.

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Knotts, Jr.

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Cyrus Group / General Managers I&E (Washington)

O. S. Bradham Document Management Branch R.

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Mr. James P.

O'Reilly LER No.83-036 i

Page Two May 13, 1983 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES On April 14, 1983, with the Plant in Mode 5, the Pressurizer Safety Valve Position-Indication on valves XVR-8010 A, B,

and C failed.to function properly during the performance of a channel calibration.

The Main Control Board indication of valve position was received during the simulated valve opening, however, once the lights were illuminated, they would not change state to indicate further movement of the valve (i.e. closed, intermediate, and open indication were all present).

The valve position indication switch assemblies were originally installed and tested in accordance with the manufacturers' recommendations on April 23, 1982.

Testing performed at that time verified correct switch operation from the valve to the local cable junction box.

Verification of the Main Control Board position indication / alarm functions was performed with an independent test on June 21, 1982.

The independent test was performed by simulating switch closure at the cable junction box.

The Pressurizer Safety Valve Position Indication is identified in Technical Specification 3.3.3.6, Table 3.3-10, Item 22, and is required to be operable while the plant is in Modes 1, 2,

and 3.

Operations personnel would have been aware of any opening of a Pressurizer Safety Valve as indicated by the April 14, 1983, test results. 'However, one of the three alternate monitoring methods would have been required to determine actual valve position after lifting.

The alternate monitoring methods available are:

i 1.

Temperature detectors in the piping downstream of the valves.

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2.

Acoustic Leak Monitoring System.

I 3.

Pressure, temperature, and level in the Pressurizer Relief Tank.

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Mr. James P. O'Reilly LER No.83-036 Page Three May 13, 1983

CAUSE AND CORRECTIVE ACTIONS

The switch contacts were found to be fused shut upon disassembly by maintenance personnel.

Engineering, through discussions with the vendor and other customers, determined that the cause of the excessive current and subsequent contact damage was the discharge of the cable capacitance.

The original acceptance test failed to discover this problem since each portion of the circuitry was subjected to En independent test.

The damaged switch assemblies have been replaced, and the circuitry is presently being modified to include a resistor adjacent to the switches.

The resistor will limit tne current flow through the contacts in order to prevent a future recurrence of the failure.

A test of this modification, which cycled the switches approximately 100 times with no failures, was performed on April 28, 1983.

The modification and subsequent Channel Calibration will be completed prior to entry into Mode 3.

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