ENS 46521
ENS Event | |
|---|---|
06:20 Jan 5, 2011 | |
| Title | Reactor Core Isolation Cooling Declared Inoperable |
| Event Description | On January 5, 2011, at 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br />, with the reactor at 100% thermal power and steady state conditions, Pilgrim Nuclear Power Station (PNSP) declared the Reactor Core Isolation Cooling (RCIC) system inoperable due to the RCIC suction isolation valve from the Torus/Suppression Pool (RCIC-26) failing to go fully closed during planned surveillance testing. The RCIC-26 is a motor-operated valve (MOV) and its normal position is closed. The RClC-26 valve is redundant to the RCIC-25 valve, and is not the credited containment isolation valve. The RCIC-26 valve has a safety function to be (manually) opened during certain event mitigation scenarios requiring a transfer of suction sources from the Condensate Storage Tank (CST) to the Torus.
Based on the valve failing to fully close during MOV stroke time testing per PNPS Procedure 8.5.5.4, the RCIC system was declared inoperable at 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> and the appropriate LCO was entered. The RCIC-26 was subsequently returned to a full open position, caution tagged and the RCIC system was declared operable. The LCO was exited at 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />. An investigation of the event is underway and continuing. This event had no impact on the health and/or safety of the public. The NRC Resident Inspector is on-site and has been notified. This is an 8-hour notification made in accordance with 50.72(b)(3)(v)(D). The licensee will notify the State of Massachusetts.
Event Notification 46521 was conservatively made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10 CFR 50.72 were satisfied pending the evaluation of RCIC System operability. On 01/05/11, at 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> the RCIC System was declared inoperable due to uncertainty of RCIC System Operability when the Torus/Suppression Pool Suction Valve (RCIC-26) failed to go fully closed during planned surveillance testing. The valve was restored to the full open position and the valve was declared operable based on capability to meet the required safety function to fully open when RCIC pump suction from the suppression pool is required. The apparent cause evaluation concluded that valve failure was the result of high relay contact resistance in the closing control circuit components of the valve breaker. This failure prevented the valve from fully closing but had no affect on capability to open the valve. Surveillance testing verified that capability to open the valve was not affected. Corrective action was completed to clean or replace the control circuit relay contacts. Post work testing confirmed capability to open and close the valve. An extent of condition for similar breaker control circuit components was also performed. All relevant technical information is documented in the corrective action system. The failure observed did not affect the valve's required safety function and did not impact RCIC System operability. Thus there was no impact on nuclear safety. This event is not reportable pursuant to 10 CFR 50.72(b)(3)(v)(D) . Event Number 46521, made on 01/05/2011, is being retracted. The licensee has notified the NRC Resident Inspector. Notified R1DO (Anthony Dimitriadis) |
| Where | |
|---|---|
| Pilgrim Massachusetts (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+2.72 h0.113 days <br />0.0162 weeks <br />0.00373 months <br />) | |
| Opened: | Mert Probasco 09:03 Jan 5, 2011 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Mar 4, 2011 |
| 46521 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |