ML20214P284
| ML20214P284 | |
| Person / Time | |
|---|---|
| Site: | University of Missouri-Columbia |
| Issue date: | 09/10/1986 |
| From: | Alger D, Meyer W MISSOURI, UNIV. OF, COLUMBIA, MO |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8609170385 | |
| Download: ML20214P284 (4) | |
Text
,
o II Research Reactor Facility September 10, 1986 UNIVERSITY OF MISSOURI Research Park Columbia, Missouri 65211 Telephone (314) 882-4211 Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555
REFERENCE:
Docket 50-186 University of Missouri Research Reactor License R-103
SUBJECT:
Report.as required by Technical Specification 6.1.h(2) concerning reactor operation with an abnormal valve lineup for the Emergency Pool Fill System.
INTRODUCTION:
The Technical Specification for limiting conditions on reactor auxiliary systems states that "the reactor shall not be operated unless the emergency pool fill system is operable" [ Technical Specification 3.10(c)]. The technical speci-fication definition of operable (1.12) states "that a system is operable when it is capable of performing the intended function in a normal manner".
The reactor operated from May 1, 1986 to August 15, 1986 with the Emergency Pool Fill System in an abnormal valve lineup, due to one valve (PIV-1) being closed that is normally locked open.
In this valve configuration, two valves would have had to be opened to initiate emergency pool fill flow rather than one valve. Therefore, for the period of time that the reactor operated with the post indicator valve to the Emergency Pool Fill System closed, the emergency pool fill system was operable, but in a state of reduced effectiveness.
DESCRIPTION:
On August 15, 1986, a reactor operator found the post indicator valve (PIV-1) for the fire main water supply to the Emergency Pool Fill System in the closed position (see Fig. 1). This valve is normally placed in the locked open position during reactor operation, leaving a single manually operated isolation valve at the reactor bridge capable of initiating emergency pool fill.
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Director September 10, 1986 Page 2 The last recorded manipulation of this post valve occurred on May 1, 1986, when it was shut and tagged out for testing of the fire' main. The tag log and console log indicate that the tag was removed and the valve was reopened at 1100 on May 1,1986, but it. appears the tag may have been cleared without reposition-ing the valve to the open position. With the post valve closed, initiation of emergency pool fill flow would have required manually opening two valves instead of manually opening one valve on the reactor bridge.
Having the post indicating valve shut also isolates the fire main pressure indication and alarm from the fire main system. Reactor operators monitor this low pressure alarm (108 psig) in the control room and check the fire main pressure indication whenever the alarm condition annunciates. Operator response to a loss of fire main pressure would result in a reactor shutdown as per REP-11, low Fire Main Pressure. During the time PIV-1 ~was shut, the low pressure alarm never actuated, indicating that water pressure was being sensed by leakage through the valve seat on PIV-1. Furthermore, the pressure indication and alarm system for the Domestic Cold Water (DCW) System monitors the water pressure of the water sup-ply that is common to both the DCW system and the emergency pool fill flow system (see Fig.1) and would have alerted the control room operator to any situation where insufficient water pressure was available to provide the minimum 1000 gpm required by Hazards Summary (Reference 13.2.4 of HSR and Section 3.16 of Addendum 1 to HSR.)
ANALYSIS:
The Emergency Pool Fill System is designed to assure that pool water level will remain above the reflector in case a six-inch beamport or a six-inch pool coolant line is sheared (Reference Section 13.2.4 and 13.2.5 of HSR). The capa-bility of the Emergency Pool Fill source is verified greater than 1000 gpm by a semiannual compiiance procedure (CP-16). The most recent compliance check was performed April 17, 1986 and the capability was determined to be 1216 gpm. There was never an indication during reactor operation from May 1,1986 to August 15, 1986 that insufficient water pressure was available to provide the minimum emer-gency pool fill flow of 1000 gpm. The reduced effectiveness of the Emergency Pool Fill System during this time can be attributed to the isolation valve (PIV-1) that was found closed which normally should be locked open.
Had Emergency Pool Fill flow.been required, a reactor operator would have had to recognize after opening the single isolation valve on the reactor bridge, that the second valve (PIV-1) required opening.
It would take a reactor operator, at the reactor bridge, less than two minutes to get to and open PIV-1.
It is pertinent to point ~out that the-emergency procedure that calls for initiating Emergency Pool Fill Flow, REP-15, LOSS E P0OL WATER LEVEL DURING REACTOR OPERATION, recognizes this source of raw water as the last water source utilized, and then only if the pool leak cannot be secured and a core void is suspected. Provisions are made. to gravity feed or pump the contents of the 7000 gallon demineralized water storage tank into the pool in tne event of pool water loss before considering the addition of raw water via the Emergency Pool Fill System.
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Director September - 10,1986 Page 3 The cause of the abnormal valve lineup in the Emergency Pool Fill System was improper clearing of the red tag attached to PIV-1 on May 1,1986. The operator clearing the tag failed to reposition the valve to the locked open position.
CORRECTIVE ACTIONS:
As stated above, failure to reposition valve PIV-1 after removing its red tag was the cause of reduced effectiveness of the Emergency Pool Fill System. Each reactor shift supervisor will address this problem with his shift to ensure all operators recognize the need, after removing a tag, to check the position of any valve, switch.or equipment to ensure it is in the proper position / condition for reactor operation.
As a further control, an entry will be made in the Reactor Startup Checksheet to have reactor operators " Check valves PIV-1 and PIV-2 locked open" prior to reactor startup.
Si cerely, b
Walt A. Meyer, J Acting Reactor Manager Endorsement:
Reviewed and Approved g
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Don M. Alger
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Associate Director Attachment RARY MARTIN xc:
U. S. Nuclear Regulatory Commission notanY PUBLIC STAti CF Mi$$MRI c/o Document Control Desk co m co-NT Cou!$SION EXP. MAR.1,1970 3 * ' * * * ' "' " #8 *
- James Keppler, Regional Administrator US NRC, Region III Reactor Advisory Committee Reactor Safety Subcommittee l
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