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On 9/18/13, during performance of the High Pressure Coolant Injection (HPCI) pump operability surveillance, a minor steam leak was discovered on the governor valve inspection cover flange. Due to the leak, HPCI was declared inoperable. Actions taken: A 14-day LCO per TS 3.5.E.2 has been entered and corrective actions are in progress. The licensee has notified the NRC Resident Inspector.

• * * RETRACTION FROM BENJAMIN EGNEW TO HOWIE CROUCH AT 1341 EDT ON 10/31/13 * * *

After further evaluation, the gasket leak at the flange was determined to have no impact on the operability of the HPCI system, and therefore the HPCI system was able to perform all safety functions with the identified condition. The immediate determination, made on September 18, 2013, that the HPCI system was inoperable was revised based on the results of an analysis of the HPCI room heat up rate. The heat up rate was modeled using a calculated steam leak rate based on actual measurements of the damaged gasket after removal from the HPCI turbine flange. The time to heat up was based on the first set point at which isolation due to a temperature increase would occur. It was determined that the existing gap in the gasket represented approximately one-tenth of the approximate size of a steam leak that would be expected to result in an isolation, therefore the existing flange leak had no impact on operability of the HPCI system or its ability to mitigate the consequences of an accident. The licensee has notified the NRC site Resident Inspector. Notified R1DO (Krohn).

The licensee discovered that the High Pressure Coolant Injection (HPCI) system flow control loop was degraded in such a manner that HPCI would not perform its safety function. The HPCI loop flow indicator indicated 200 GPM with no flow in the loop. The specification for that parameter is <100GPM. With the flow indicator in this condition the HPCI flow controller would perform non-conservatively (less flow into the system than was demanded), and would not perform its intended safety function therefore rendering HPCI inoperable. The licensee declared HPCI inoperable and in accordance with Technical Specification 3.5.E.2 entered a 14 day LCO. The licensee has commenced troubleshooting and will initiate repairs as necessary to return the system to operation. The licensee notified the NRC Resident Inspector.

• * * RETRACTION ON 03/09/07 AT 1413 EST FROM M. RAMSEY TO MACKINNON * * *

BASIS FOR RETRACTION: NRC Event Notification 43113 was conservatively made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10CFR50.73 were met pending the evaluation of an atypical condition observed with the High Pressure Coolant Injection (HPCI) Flow Indicator that was observed by Operators during routine monitoring of plant equipment. After comparing the observed flow indication to allowable values for meter uncertainties, it was determined that the initial NRC Notification was not required. The HPCI system was capable of fulfilling all design safety functions. Additional measures to ensure system reliability were completed that included removing and bench testing the recently refurbished 'square root converter' and calibration verification of involved components. No degraded conditions were discovered. ENS Event Number 43113, made on 01/22/07, is being retracted. R1DO (Neil Perry) notified. The NRC Resident Inspector was notified of this retraction by the licensee.

The HPCI flow control current loop was found degraded in such a manner that HPCI would not perform its intended function. HPCI was declared inoperable per TS 3.5.E.2 (14 day LCO). Repair efforts have been initiated. The licensee notified the NRC Resident Inspector.

• * * RETRACTION FROM M. RAMSEY TO M. RIPLEY AT 1601 ET ON 02/16/06 * * *

On 12/22/05, the HPCI System flow indicator 'spiked' a number of times with the system in its normal standby line-up. Control Room Operators declared the HPCI system inoperable and entered a 14 day LCO per TS 3.5.E.2, to troubleshoot and repair the system as appropriate. The safety function of HPCI system is to provide and maintain an adequate coolant inventory inside the reactor vessel to prevent fuel clad conditions from exceeding 10CFR50.46 criteria as a result of postulated small breaks in the Nuclear System process barrier. To ensure that this safety function is met, the HPCI System must be able to deliver a minimum actual flow rate of 3570 gallons per minute (gpm) to the reactor vessel. The actual flow rate was reduced below the Technical Specification value of 4250 gpm to account for potential flow instrument string inaccuracies. The delivery of 3570 gpm of actual flow demonstrates that sufficient margin to safety function is maintained during accident conditions. In automatic operation, the HPCI flow controller uses the flow signal to maintain a flow rate of 4250 gpm and is designed to automatically adjust developed flow rate in response to changes in flow signals. System operation is tested quarterly by monitoring flow to ensure that the HPCI system can perform its safety functions. The Technical Specification surveillance requirement states that the HPCI system shall deliver at least 4250 gpm at normal reactor operating pressure when recirculating to the Condensate Storage Tank. The event investigation revealed that the cause of the flow spikes was a malfunctioning electrical component in the power supply module within the flow controller. Power to the flow transmitter is supplied by this module. The power supply would malfunction for a few seconds and then would return to normal operation, thereby resulting in step changes in the HPCI flow signal. It is conservative to assume the actual HPCI flow rate would have been reduced by the full amount of the flow rate, for the entire duration of the flow signal. Additional conservatism also exists because the HPCI system flow is unlikely to have been able to respond to the full value of a short duration flow spike. When calculating the average HPCI flow rate, the impact of the flow spikes decreases as a longer period is evaluated because the duration of all of the flow spikes added together is very short and comparably longer periods of stable performance exist between the individual spikes. Therefore, it is conservative to evaluate the shortest period of time that HPCI is required to perform its safety functions that is stated in the Design Bases Document as 1000 seconds. With HPCI operable, the worst case period occurred just prior to it being declared 'Inoperable'. HPCI was calculated to have developed an actual flow rate of greater than 4191 gpm during the worst case 1,000 second period. The calculation for 'HPCI Flow Control & Indication Loop Accuracy' provides total loop accuracy of plus or minus 216.2 gpm at 4250 gpm for Design Bases Accident conditions. A calculated flow rate of 4191 gpm, minus the flow instrument loop uncertainty of 216 gpm yields a worst case actual flow rate of 3975 gpm. A flow rate of 3975 gpm is greater than the 3570 gpm assumed in event calculations. The subject flow controller power supply module was removed and bench tested to demonstrate that sufficient operating margin existed to provide reasonable assurance that the power supply would not have failed if called upon to mitigate a design bases accident with sufficient margin. The testing simulated HPCI operation at 4250 gpm for more than 24 hours. No flow spikes were recorded during this period. Based upon these test results and the analysis provided above, if the subject power supply component had remained in service and HPCI operation was required, the system would have performed its required safety function for a duration exceeding any analyzed event. ENS Event Number 42219, completed on 12/22/05, is being retracted. The licensee notified the NRC Resident Inspector. Notified R1 DO (J. Trapp)