ML20003B263

Ro:On 810109 & 10,reactor Operated W/Low Air Flow Through Stack Radiation Monitor.Caused by Associated Air Blower in Secured Position.Blower Turned on When Found Secured.Stack Monitor Filters Pulled & Counted

ML20003B263
Person / Time
Site:	University of Missouri-Columbia
Issue date:	02/05/1981
From:	Brugger R, Mckibben J MISSOURI, UNIV. OF, COLUMBIA, MO
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8102100565
Download: ML20003B263 (2)

Text

1 Research Reacter Facility UNIVERSITY OF MISSOURI pesea,cn p3.,

csurre a %sscun G5211 February 5, 1981 Director of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Reference:

Docket 50-186 University of Missouri License R-103

Subject:

Report as required by Technical Speci fication 6.1.h(2).

Description On January 9 and 10, 1981, the reactor was operating with low air flow through the stack radiation monitor due to the associated air blower being secured. The particulate, gas and iodine indication and alarm instrumentation was operating properly but the low air flow by the detectors resulted in unreliable information being presented to the reactor operator. Operating without sufficient reliable information is a violation of Technical Specification 3.4.a.

Analysis At approximately 1630, during a reactor start-up check, the Electronic Shop personnel performed an electronic calibration of the iodine instrument. As a pre-caution, to prevent the test equipment cables from becoming entangled in the stack monitor blower fan belt, the blower was secured. Upon completion of the calibration, the iodine instrument was verified operable and returned to normal operation, but the blower was inadvertently left secured. The reactor was then operated at 10 MW from 1742, January 9, through 1422, January 10, with the blower secured. A total of 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />, 40 minutes elapsed with low stack monitor air flow. Technical specifica-tions permit the nonitor to be placed out of service for up to two hours providing there is no experiment or maintenance activities that would likely result in the release of unknown quanities of airborne radioactivity.

With the blower secured, the differential pressure across the stack nonitor caused a flow rate of 7.5 liters / minute compared with the normal blower induced flow rate of 235 liters / minute. The reduced flow rate likewise reduced the depo-sition rate of activity on the filters used by the particulate and iodine detectors.

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05 rector of Licensing February 5,1981 Page 2 Therefore, the counts per minute indicated in the control room for a given amount of activity in the exhaust stack would be lower with the blower off. The stack nonitor charts were reviewed and the stack monitor filters were counted to detect acti vi ty. Additionally, the charcoal filter from an experimental iodine monitor, which was furctioning properly during this ceriod, was pulled and counted for activity. Al? ana'yses showed the stack gas, particulate, and iodine activities to be normal ano vi thin technical specification limits during the period the blower was secured.

The stack monitor has a low /high flow alarm, but an investigation of the as-sociated electrical circuitry revealed securing the blo.ser electrical power also secured the alarm power thus Taking the control roon alarm inoperable.

Corrective Action The blower was immediately turned on when found secured. As stated before, the stack monitor filters were pulled and counted. The stack monitor charts were reviewec:. Tne electrical power for the alarm monitor circuit in the control room will be separated from the blower power and a run light indication will be added in the control room in addition to the existing high and low air flow alarm. An operability check of the air flow system will be added to the Standard Operating Procedures' Pre-start Up Check Sheet to be performed in conjunction with other stack monitor operational tests.

Sincerely, ,_

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(/ J. C. McKibben React,o  % ager Endo rs emen t Reviewed and approved: /

Q- j) lbf obert M. Brdgger '

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Director JCMK:vs cc: James Keppler, Director Regulatory Operations - Region III Reactor Advisory Committee Reactor Safety Subcommittee Document Management Branch, NRC