ENS 52327
ENS Event | |
|---|---|
14:24 Oct 28, 2016 | |
| Title | Shutdown Cooling System Declared Inoperable |
| Event Description | At 0851 [EDT] on October 28, 2016, Division 1 RHR was started in shutdown cooling (SDC) mode of operation. Prior to starting the RHR system, the Alternate Decay Heat Removal (ADHR) system was maintaining RPV and Spent Fuel Pool temperature.
At 0924 on October 28, 2016, RHR [pump A] tripped due to RHR-MOV-17 (SDC suction valve) closing. This is considered to be an event or condition that could have prevented fulfillment of a safety function, and is reportable under 10 CFR 50.72(b)(3)(v)(B). RHR SDC subsystem A was declared inoperable. CNS [Cooper Nuclear Station] entered LCO 3.9.7, Condition A - Required Action A.1: Verify an alternate method of decay heat removal is available within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter; Condition C - Required Action C.1: Verify reactor coolant circulation by an alternate method within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from discovery of no reactor coolant circulation and once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter, and Required Action C.2: Monitor reactor coolant temperature hourly. All LCO conditions specified have been met. ADHR remained in service throughout the event and the plant remained aligned for natural circulation. Spent fuel pool weir temperature monitoring was commenced to verify natural circulation. No increase in RPV [reactor pressure vessel] temperature has been observed. There was no impact to plant operations. Initial investigation indicates that installation of PCIS relay K27 during a maintenance activity physically agitated the adjacent relay, K30, which actuated and caused RHR-MOV-17 to close. The NRC Resident Inspectors have been informed. |
| Where | |
|---|---|
Cooper  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| LER: | 05000298/LER-2016-007 |
| Time - Person (Reporting Time:+2.83 h0.118 days <br />0.0168 weeks <br />0.00388 months <br />) | |
| Opened: | Aric Harris 17:14 Oct 28, 2016 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Oct 28, 2016 |
| 52327 - NRC Website
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