ENS 46996

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v t e ENS Event
05:05 Jun 28, 2011
Title	Failure of #2 Fire Water Pump to Realign
Event Description	At 0005 CDT, on 06-28-2011, the Plant Shift Superintendent was notified that the C-631 High Pressure Fire Water (HPFW) pumps #2 and #3 automatically started in response to low HPFW header pressure created by a line leak and rendered inoperable. Following isolation of the water leak the #2 and #3 pumps were shut down and were being configured for automatic start. The RCW operator observed the 'Auto Start' Indicator for the #2 pump was not illuminated. The pump was declared inoperable and power was removed from the #2 pump for troubleshooting and repair by electrical maintenance (EM). When power was removed from the pump the HPFWS could not perform its intended safety function of providing 4875 gpm. Two HPFW system pumps are required to be operable according to TSR LCO 2.4.4.8. EM reset a disconnect interlock switch which reenergized the 'Auto Start' controls and the pump was declared operable and returned to service. This event is reportable under 10 CFR 76.120(c)(2) as an event in which equipment required by the TSR is disabled or fails to function as designed. The NRC Senior Resident Inspector has been notified of this event. * * UPDATE FROM KEVIN BEASLEY TO PETE SNYDER AT 1613 EDT 6/29/11 * * * Due to the uncertain nature of the leak on the 16 inch underground High Pressure Fire Water (HPFW) distribution main, it is not known at this time if the two operable HPFW pumps would have been able to satisfy the maximum sprinkler system demand of 4875 gpm. Upon completion of excavating the area of the leak, Engineering will evaluate the failure mode to determine if system requirements were maintained. The licensee notified the NRC Resident Inspector. Notified R2DO (M. Franke) and NMSS (R. Johnson). * * RETRACTION FROM CALVIN PITTMAN TO KARL DIEDERICH AT 1423 EDT 07/14/11 * * * Upon further evaluation it was determined that the (High Pressure Fire Water System) HPFWS was capable of fulfilling its intended safety function at all times during the incident. The safety function of the High Pressure Fire Water System established in SAR 3.15.7.2 is to provide sufficient fire suppression capability for the cascade process buildings to minimize the likelihood of a large fire. Fire scenarios were evaluated to establish the system design basis. A lube oil spill fire on the operating floor resulted in the highest sprinkler flow rate demand of 3200 gpm. A 500 gpm hose stream demand is added to the sprinkler system flow rate to obtain a maximum fire water flow rate of 3700 gpm for the evaluation basis fire event. As stated in the TSR 2.4.4.8 Basis Statement, the requirements for HPFWS operability established in TSR 2.4.4.8 are conservative with respect to the system evaluation presented in SAR 3.15.7.2. TSR SR 2.4.4.8-4 requires an annual flow rate verification of each HPFW pump. The most recent flow rate tests performed in Nov. 2010 demonstrate the capacity of each pump exceeds the evaluation basis flow demands. During the short time where only HPFW pump #3 was operable, this pump could have supplied more than the 3700 gpm required to satisfy the evaluation basis flow demand. The HPFWS remained capable of fulfilling its intended safety function. In addition, when HPFW pumps #2 and #3 were running in response to the leak on the underground distribution system, system pressure was approximately 134 psig. Using the pump curves established by the annual TSR surveillance test discussed above, this equates to a flow rate of approximately 5900 gpm. Any sprinkler system activation on the HPFWS would drop the system pressure to around 125 psig, slightly lowering the flow rate through the leak. During the time frame the leak was active, the HPFWS remained capable of fulfilling its intended safety function. The combined pump capacity of pumps #2 and #3 (10,600 gpm) demonstrated by the annual surveillance test exceeds the combined demand from the leak (5900 gpm) and the evaluation basis flow requirements (3700 gpm). Therefore, the HPFWS remained operable throughout the incident of the underground piping leak and the following time period of only one pump operable. Thus, reporting per 10 CRF 76.120 was not required and the subject notification can be retracted. The NRC Senior Resident Inspector has been notified of this retraction by the licensee. Notified R2DO (Freeman) and NMSS (Rahimi).

ENS 46996 +/- *RETRACTED*
Where
Paducah Gaseous Diffusion Plant Paducah, Kentucky (NRC Region 2)
License number:	Gdp-1
Reporting

10 CFR 76.120(c)(2)
Time - Person (Reporting Time:+18.08 h0.753 days <br />0.108 weeks <br />0.0248 months <br />)
Opened:	R. J. Cook 23:10 Jun 28, 2011
NRC Officer:	Pete Snyder
Last Updated:	Jul 14, 2011
46996 - NRC Website
v • d • e

v t e Emergency Notification System
Paducah Gaseous Diffusion Plant with 10 CFR 76.120(c)(2)
WEEKMONTHYEAR2014-05-08T15:24:00 [Table view]
[ENS list for Paducah Gaseous Diffusion Plant]

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