ML20236S292

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RO-19:on 980720,reactor Operation w/in-operable Alarm Circuit on Bridge Radiation Monitor,Was Disabled.Caused by Spurious Alarms Due to Temperature & Humidity Sensitivity. Reactor Shutdown Pending Further Investigation
ML20236S292
Person / Time
Site: University of Michigan
Issue date: 07/20/1998
From: Simpson P
MICHIGAN, UNIV. OF, ANN ARBOR, MI
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9807240242
Download: ML20236S292 (1)


Text

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. The . Univ:rsity cf Michigrn Michig:n M:mtri:1 Phoenix Prd:ct Phoenix Memorial Laboratory Ford Nuclear Reactor 2301 Bonisteel Boulevard Ann Arbor, Michigan 48109-2100 Tel. 734-764-6220 Docket 5024 License R-28 United States i+.uclear Regulatory Commission Document Control Desk Washington, D.C. 20555 1

Re: Reportable Occurrence No.19 - Reactor Operation with In-Operable Alarm Circuit on the Bridge Radiation Monitor.

Date July 20,1998 At approximately 15:45 today it was brought to my attention that the 0000 - 0800 shift crew had disabled what I think they believed to be the local alann circuit in the Ford Nuclear Reactor's Bridge Radiation Monitor. The monitor had been giving spurious alarms due to temperature and humidity sensitivity. The reactor was shutdown at 15:48 and an initial investigation was started.

The bridge radiation monitor is Required Safety Related Equipment and is required to be

! functioning during reactor operation with an alarm setpoint not to exceed 50 mr/hr . The l actual setpoint is 40 mr/hr. Operation of the reactor without a functioning Bridge Radiation l Monitor alarm circuit is believed to be a violation of the Limiting Conditions for Operation as defined in the FNR Technical Specifications for the Ford Nuclear Reactor.

~ The radiation measurement circuit of the monitor was not disabled with the alarm circuits and continued to be displayed and recorded on the Radiation Recorder in the Reactor Control Room. A review of the chart record showed no abnormal readings during the approximately 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> that the bridge radiation monitor alarm circuits were disabled.

Immediate ActionsTaken The reactor was shutdown and will remain shutdown pending further investigation.

Sinc rly,

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alip Simpson l g Assistant Laboratory Manager xc: Ron Fleming, Director .1 Judy Nowak, OVPR P John Lee, FNR SRC 4( i Bernard Ducamp, FNR ARM Seymour Weiss, USNRC Theodore Michaels, USNRC Tom Burdict, USNRC 9807240242 990720 PDR ADOCK 05000002 S PDR <

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