05000440/FIN-2007005-11
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Finding | |
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Title | Adequacy of Reactor Core Isolation Cooling System Flow Controller Tuning Procedures |
Description | On November 28, 2007, the inspectors observed licensee actions in response to a scram with complications. The digital feedwater level control system experienced a loss of two power supplies. This caused a loss of feedwater, main turbine trip, and reactor scram due to an erroneous reactor vessel water level 8 signal. The loss of feedwater caused an actual reactor vessel water level 2, which initiated both RCIC and high pressure core spray (HPCS) for reactor vessel water level control. RCIC tripped approximately 13 seconds after initiation due to low suction pressure, and reactor vessel control was maintained using HPCS. The inspectors observed licensee personnel shutdown the plant to Mode 4. A Special Inspection Team was chartered to investigate this event, and the results are documented in IR 05000440/2007010. At the end of the inspection period, the inspectors continued to evaluate the adequacy of the RCIC flow controller tuning procedure. A contributing cause of the November 28, 2007, RCIC failure was determined to be an improperly tuned flow controller. Following this failure, the licensee revised the tuning of the RCIC flow controller, tested the new settings, and determined that RCIC was operable on December 10, 2007. On December 12, 2007, the licensee declared RCIC inoperable due to questions over the appropriateness of the flow controller settings and whether the settings provided a sufficiently over-damped response for conditions of RCIC injection to the reactor vessel from the suppression pool. The licensee again revised the RCIC flow controller settings and returned the settings to values associated with successful injection testing to the reactor during baseline pre-startup testing. Following additional testing using the condensate storage tank and further evaluation, the licensee declared RCIC operable again on December 21, 2007. |
Site: | Perry |
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Report | IR 05000440/2007005 Section 4OA3 |
Date counted | Dec 31, 2007 (2007Q4) |
Type: | URI: |
cornerstone | No Cornerstone |
Identified by: | NRC identified |
Inspection Procedure: | IP 71153 |
Inspectors (proximate) | M Wilk A Dahbur G Wright M Franke J Cameronm Wilkr Jickling J Robbins D Reeser M Franke B Burgess J Quichocho R Leidy T Mccall T Taylor |
INPO aspect | |
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Finding - Perry - IR 05000440/2007005 | |||||||||||||||||||||||||||||||||
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Finding List (Perry) @ 2007Q4
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