ML19338G049

Submits Rept Re 800922 Semiannual Compliance Check on Reactor Coolant Inlet High Temp Scram Unit 980A.Meter Relay Control Unit Scram Did Not Actuate in Response to High Temp Signal.Unit Was Replaced

ML19338G049
Person / Time
Site:	University of Missouri-Columbia
Issue date:	10/20/1980
From:	Brugger R, Mckibben J MISSOURI, UNIV. OF, COLUMBIA, MO
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8010280378
Download: ML19338G049 (2)

Text

_ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _

1 Research Raactor Facility UNIVERSITY OF MISSOURI Research Park Columbia. Missouri 65211 October 20, 1980 Teteonone (314) 882-4211 Director of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 23555

Reference:

Docket 50-186 University of Missouri License R-103 ,

Subject:

Report as required by MURR Technical Specification 6.1.h(2).

Description On September 22, 1980, while performing a routine semi-annual compliance check on the reactor coolant inlet high temperature scram unit 980A, it was found the meter relay control unit scram did not actuate in response to a high temperature signal. Operation of the reactor with this meter relay trip in-operable deviates from MURR Technical Specification 3.3.2 in that one of the three reactor coolant temperature scrams was not operable.

Analysis The reactor was in the shutdown mode, with all control rods fully inserted.

A test signal was being fed into the 980A meter relay trip unit as part of the compliance check procedure. The meter indication was in calibration but the meter relay contacts failed to open. A new meter relay control unit was in-stalled.

To investigate the malfunction, the old meter relay control unit was con-nected to a test signal in the Electronic Shop. The capacitance value of a capa-citor located in the meter relay control circuit had decreased and caused the failure. The original value of the capacitor was 330 pf 0 6V. The measured value of the capacitor had decreased to about 80 uf. Because of the reduced capacitance value, the capacitor did not charge sufficiently for the meter re-lay control circuit to function properly.

The reactor coolant inlet high temperature instrument channel, 980A, was added to the reactor instrumentation in July 1973. There have been no other 1 I

[oAo s

% \# /!O E

E ROLLA COLUMBIA KANSAS CITY ST. LOUIS B010280 Q .n eaua n npormn e nsnmuon P

Director of Licensing October 20, 1980 Page 2 operational problems with the 980A channel since its installation. This channel is one of seven instrumentation channels that contain meter relay control units at MURR. One other deviation from technical specifications due to a failure of i

a meter relay control unit occurred on July 3,1978, when mechanical binding in the relay caused the failure (L.E.R. dated August 2,1978).

The reactor safety system was still capable of perfonning its safety function if a high reactor coolant temperature condition had occurred, due to b'oth the reactor high outlet temperature scram, 9018, and the other reactor inlet high temperature scram, 9808, being operable (Hazard Summary Analysis, Addendum 4, Appendix A.3.3.6).

Corrective Action The meter relay control unit was replaced with a new unit and the 980A com-pliance check was performed. In addition, the regularly scheduled compliance checks for 9808 and 901B were performed with all scrams actuating within techni-cal specification limits.

The control' circuit capacitor for the other six meter relay control units will be tested when their respective semi-annual compliance check procedures are scheduled to be completed. In addition, all seven capacitors will be retested every five years.

Sincerely, s . g J. C. McKibben React anager Endorsement: .

Rrviewed and Approved -

Or. Robert M. Brug e Director JCMK:vs ccN.S. Nuclear Regulatory Commission c/o Document Management Branch James Keppler, Director Regulatory Operations - Region III Reactor Advisory Committee Reactor Safety Committee

,