05000373/FIN-2011002-04
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Finding | |
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| Title | Potential Failure to Make a Non-Emergency Event Notification to the NRC Following a Loss of Shutdown Cooling Safety Function on Unit 1 |
| Description | The inspectors identified an Unresolved Item (URI) associated with the potential failure to make a non-emergency eight-hour notification to the NRC in accordance with 10 CFR 50.72 (b)(3)(v) for a loss of safety function of a system which was required to remove residual heat from the reactor. This item remains unresolved pending further review by the NRC staff. On February 2, 2011, Unit 1 was in hot shutdown (Mode 3) following an unexpected scram that occurred the previous day. The control room operators were in the process of placing the B train of shutdown cooling in operation. When the B RHR pump was started, the initial flow conditions created a spurious closure of the common pump suction valve, CIV 1E12-F009, on a sensed high-flow condition. This containment isolation valve is designed to prevent a loss-of-coolant accident outside of containment due to a leak in the RHR system. If a higher than expected flow is sensed in the common suction piping, a control relay will cause a closure of the1E12-F009 valve to stop the potential interfacing system loss-of-coolant accident. The closure of this common suction valve resulted in the B RHR pump tripping and a complete isolation of shutdown cooling. The licensee declared both trains of shutdown cooling inoperable and entered Technical Specification (TS) 3.4.9, RHR Shutdown Cooling Hot Shutdown, which requires, in part, for the immediate initiation of actions to restore the RHR shutdown cooling subsystem to operable status. In order to prevent spurious containment isolations, the licensee had proceduralized the installation of jumpers that bypass the relays that would cause the containment isolation to occur, based upon previous operating experience. Following the closure of valve 1E12-F009 and the isolation of shutdown cooling, equipment operators installed jumpers to bypass the containment isolation. The control room operators reset the containment isolation logic, re-opened the 1E12-F009 valve, started the B RHR pump, and placed that train in operation. Once the RHR system was operating in shutdown cooling mode, the jumpers to defeat the high flow isolation were removed, shutdown cooling was declared operable, and the associated TSs were exited. The licensee reviewed the event for 10CFR 50.72 reportability, but determined that it was not reportable since the closure of 1E12-F009 was considered spurious and it occurred during system startup, hence, shutdown cooling was never established. As such, this event was not characterized as an event or condition that could have prevented the fulfillment of a safety function. The inspectors consulted NUREG-1022, Revision 2, Event Report Guidelines 10 CFR 50.72 and 50.73, which is considered the NRC staffs position on the reporting of nuclear events. The NUREG-1022 guidance states, in part, that if a single RHR suction line valve should fail in such a way that RHR cooling cannot be initiated, the event would be reportable. The closing of the common RHR shutdown cooling isolation valve, 1E12-F009, represented this scenario. In addition, NUREG-1022 states that the event must be reported regardless of whether or not an alternate system could have been used to perform the systems safety function. In addition to the reportability aspect, the inspector is reviewing the appropriateness of the corrective actions completed by the licensee as a result of this event. The inspectors plan to engage personnel in the NRC Office of Nuclear Reactor Regulation to ensure that the licensee is implementing the reportability guidelines and regulations appropriately and to ensure that the loss of shutdown cooling by all licensees is treated consistently. An URI is opened pending further review by the NRC staff. (URI 05000374/2011002-04). |
| Site: | LaSalle  |
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| Report | IR 05000373/2011002 Section 4OA2 |
| Date counted | Mar 31, 2011 (2011Q1) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71152 |
| Inspectors (proximate) | R Jickling R Ruiz R Winter F Ramirez A Dahbur K Riemer J Yesinowski R Walton M Munirn Shahr Ruiz F Ramirez K Riemer M Mitchell J Neurauter J Yesinowski J Bozga M Learn A Scarbeary R Edwards L Rodriguez |
| INPO aspect | |
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Finding - LaSalle - IR 05000373/2011002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (LaSalle) @ 2011Q1
Self-Identified List (LaSalle)
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