ENS 44236
ENS Event | |
|---|---|
07:30 May 23, 2008 | |
| Title | Charging Pump Declared Inoperable Due to Relief Valve Lifting Below Setpoint |
| Event Description | During normal operation with 23 Charging Pump in service, 21 Charging Pump was placed in service for quarterly testing. Shortly after starting 21 Charging Pump, 23 Charging Pump relief valve lifted below its set point value. CVCS system pressure was approximately 2520 psig. This is the alternate safe shutdown pump responsible for inventory control for remote shutdown. 23 Charging Pump was declared inoperable. Recent NRC guidance indicates that a loss of a single train system not credited in accident analysis is reportable when identified in LCO 3.3.4, Remote Shutdown.
The licensee will notify the NRC Resident Inspector.
Indian Point Unit 2 is withdrawing the 8-hour non-emergency notification made on May 23, 2008, at 08:11 hours (EN#44236). The notification reported a safety system functional failure (SSFF) as a result of the relief valve for the 23 charging pump lifting below its setpoint value. The condition was discovered during Chemical Volume & Control System (CVCS) operation with the 23 charging pump in operation. Shortly after the 21 charging pump was placed in service for quarterly testing, the 23 charging pump relief valve lifted. The operating speed of the charging pumps was reduced and the 23 charging pump relief valve re-seated. The 23 charging pump is the alternate safe shutdown pump responsible for inventory control for remote shutdown from the control room. The relief valve has an active safety function in the open position to provide overpressure protection for the 23 charging pump and associated piping. The relief valve has an active safety function in the closed position to prevent charging pump discharge flow from continuously re-circulating to the pump suction. At the time of the event Operations believed the 23 charging pump relief valve lifted prematurely and declared the 23 charging pump inoperable and made the 8-hour non-emergency notification for loss of remote shutdown capability for a component specified in Technical Specification 3.3.4, 'Remote Shutdown.' The relief valve was subsequently changes out with a spare. Subsequent investigations determined that the CVCS pressure was set high in the operating band for two pump operation. Engineering determined that when the 21 charging pump was started the pulsation at the discharge of the positive displacement charging pump exceeded the limit of the relief valve pressure setting. Initial header pressure with the 23 charging pump in operation was approximately 2420 psig with typical charging header pressure at approximately 2300 psig. When the 21 charging pump was placed in service, the resultant pressure with consideration for pulsation immediately at the discharge of the charging pump would have been approximately 2701 psig. The charging pump relief valve lift pressure setting is 2735 +/- 3% (2653 psig to 2817 psig). Therefore, the resultant pressure from two pump operation was within the relief valve lifting pressure. An inspection of the removed relief valve showed only minor anticipated seat degradation of the disc ring insert. Further assessment indicated that the 23 charging pump relief valve did lift and also reseated when aligned for parallel pump operation when the CVCS pressure was adjusted. Engineering and Operations concluded that the 23 charging pump and associated relief valve were operable and capable of performing this safety function. The initial condition was determined to have been attributed to elevated initial CVCS pressure that resulted in challenging the relief valve during two pump operation. The licensee will notify the State and the Resident Inspector. R1D0 (Dentel) notified. |
| Where | |
|---|---|
Indian Point  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | |
| Time - Person (Reporting Time:+0.68 h0.0283 days <br />0.00405 weeks <br />9.31464e-4 months <br />) | |
| Opened: | Tim Buchal 08:11 May 23, 2008 |
| NRC Officer: | Jason Kozal |
| Last Updated: | Jul 21, 2008 |
| 44236 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 528012017-06-11T13:11:00011 June 2017 13:11:00
[Table view]10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor Excessive Bonnet Leakage from Chemical Volume Control System Valve ENS 467822011-04-25T13:50:00025 April 2011 13:50:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor Single Train Charging Pump Declared Inoperable ENS 463922010-11-04T05:23:0004 November 2010 05:23:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor Charging Pump '23' Declared Inoperable During Surveillance Testing ENS 462222010-09-01T20:00:0001 September 2010 20:00:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor Loss of Temperature Instrumentation ENS 454322009-10-14T19:00:00014 October 2009 19:00:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor Safety System Functional Failure - Alternate Safe Shutdown Source Range Neutron Monitor Inoperable ENS 451522009-06-23T22:23:00023 June 2009 22:23:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor Potentially Degraded Inventory Control During Shutdown ENS 442362008-05-23T07:30:00023 May 2008 07:30:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor Charging Pump Declared Inoperable Due to Relief Valve Lifting Below Setpoint 2017-06-11T13:11:00 | |