05000339/LER-2014-001
| North Anna Power Station | |
| Event date: | 02-02-2014 |
|---|---|
| Report date: | 04-02-2014 |
| 3392014001R00 - NRC Website | |
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1.0 DESCRIPTION OF THE EVENT At 0859 on February 2, 2014, with Unit 2 operating at 100% power, the "A" MFW Pump, 2-FW-P-1A (EIIS System — SJ, Component — P), had a motor lead connection that grounded and caused the power supply breakers for 2-FW-P-1A to trip open. The standby MFW pump, 2-FW-P-1C, auto started, as designed. The operating crew entered the abnormal procedure for Loss of Main Feedwater, 2-AP-31. The RO believed that one of the two tandem motors of the standby pump did not auto start, since one of the Control Room indicating lights did not illuminate as expected. The RO believed only one MFW pump was running with two required for operation greater than 70% power. Based on this indication and the perceived loss of MFW, the RO initiated a manual reactor trip as directed in 2-AP-31. Although the remaining control room team members were aware that the standby pump had auto-started, they were unable to intervene in time to prevent the manual trip. A 4-hour report per 10CFR50.72(b)(2)(iv)(B) was made at 1101 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.189305e-4 months <br /> on February 2, 2014 for manual actuation of the reactor protection system.
Following the reactor trip, all control rods fully inserted into the core and the unit was stabilized in Mode 3 at normal reactor coolant system temperature and pressure. The Auxiliary Feedwater (AFW) pumps (EIIS System — BA, Component — P) automatically started, as designed, following the reactor trip and provided makeup flow to the steam generators (EIIS System — AB, Component — SG). Steam generator levels were returned to normal operating level and the AFW pumps were returned to the normal, standby automatic alignment. An 8-hour report per 10CFR50.72(b)(3)(iv)(A) was made at 1101 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.189305e-4 months <br /> on February 2, 2014 for automatic actuation of an ESF system.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS No significant safety consequences resulted from this event because the reactor was placed in a safe condition by the RO. Ultimately there was adequate feed water and 2- FW-P-1C auto started so the unit could have remained at 100 percent power with 2-FW- P-1A tripped. The health and safety of the public were not affected by this event.
North Anna Power Station Unit 2 05000339 3.0 CAUSE The root cause of this event is that the RO did not use diverse indications for determining if MFW Pump 2-FW-P-1C was running. Thus, the Response Not Obtained (RNO) step of 2-AP-31 was performed to trip the reactor. A contributing cause was that the Supervisor did not oversee performance of the Immediate Operator Actions (I0As) by the RO in accordance with Operations Department standards.
4.0 IMMEDIATE CORRECTIVE ACTION(S) The license qualification for the RO was administratively suspended pending further investigation of the event.
5.0 ADDITIONAL CORRECTIVE ACTIONS An improvement plan will be implemented for the Supervisor to enhance oversight of control room performance. Additional corrective actions are being tracked to completion by the root cause evaluation.
6.0 ACTIONS TO PREVENT RECURRENCE A remediation plan will be developed and implemented for the RO that addresses, at a minimum, the lapses in individual performance that occurred during this event.
7.0 SIMILAR EVENTS No similar events have occurred at North Anna Power Station.
8.0 ADDITIONAL INFORMATION Unit 1 continued operating in Mode 1, 100 percent power during this event.