ML20003D676

Ro:On 810223,w/reactor Shutdown for Scheduled Maint, Isolation Valve for Containment Bldg Leak Rate Determination Sys Found in Open Position.Cause Not Stated.Valve Lineup on Containment Leak Rate Sys Conducted.Pipe Cap Installed

ML20003D676
Person / Time
Site:	University of Missouri-Columbia
Issue date:	03/20/1981
From:	Mckibben J MISSOURI, UNIV. OF, COLUMBIA, MO
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8103300297
Download: ML20003D676 (2)

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Research Reactor Facility

.K UNIVERSITY OF MISSOURI Reseatn Pstk Cotumbia. Mssoun 65211 w e n ne m as2aan March 20, 1981 p\m  %

h }..ky, 76 Director of Licensing i~ g9 hf th U. S. Nuclear Regulatory Commission Washington, D.C. 20555 f

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Reference:

Docket 50-186 University of Missouri .f:. " 4

License R-103 f@/ls!l e

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Subject:

Report as required by Technical 3pecification 6.1.h(2).

Description On February 23, 1981, with the reactor shutdown for a regularly scheduled maintenance day, an isolation valve for the containment building leak rate de-termination system was found in the open position The valve is located in a 3/4 inch line that penetrates the containment wall and is open ended on both sides. With this flow path opgn, the containment building leakage rate would probably have exceeded 16.3 ft / min with an overpressure of one pound per square inch and been out of compliance with Technical Specification 4.2.c.

Analysis At 0800 on February 23, 1981, a Health Physics Technician noticed an abnor-mal noise in the basement area outside the containment building. Investigation by the operating crew found one of the three containment leak check isolation valves to be in the open position. The, containment leak check line starts in the basement outside the containment buildinj, runs through a penetration plate, and terminates just inside the containment wall. The line is used to pressurize the containment building for the annual leak rate check. When the valve was found open, a complete valve-line-up was conducted on the leak rate system and no other discrepancies were fcund. A previous valve line-up on the containment leak rate system had been conducted in early January by a Reactor Shift Super.

visor and no vilves had been found rut of position. No evolutions involving this system had been performed in the int : rim. A white "Do Not Operate" tag had re-mained fixed to the valve throughout the interval.

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8103300297

1. eirector of Licensing March 20, 1981 Page 2 During the period the valve was in the open position, a direct pathway existed from the containment building to the facility basement. The ability of the containment building to pass the required leakage criteria outlined in Technical Specification 4.2 with this pathway open is not known. The contain-ment building _ leak rate check was last conducted on A"ril 21, 1980 with a mea-sured leak rate of 10.2 scfm with a 1 psi overpressure. If an event had oc-curred requiring containment isolation, the flow rate through this pathway would have been small, detectable, and easily secured with containment isolated.

Corrective Action A valve line-up on the containment leak rate system was immediately con-ducted with no other valves being found out of position. A pipe cap has been installed on the open-ended line inside the containment wall and the leak rate procedure has been modified to include installation of this cap at the conclu-sion of the procedure. The white "Do flot Operate" tags have been replaced with red " Danger" tags which are more readily recognized and respected by personnel.

Additionally, other pipes penetrating the containment wall were reviewed to determine the potential for similar problems in other systems.

Sincerely, ,

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J. C. McKibben Reactor Manager JCMK:vs cc: James Keppler, Director Regulatory Operations - Region III Document Management Branch, NRC Reactor Advisory Committee , ,

Reactor Safety Subcomittee .

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