05000338/LER-2014-002
| North Anna Power Station Unit 1 | |
| Event date: | 12-10-2014 |
|---|---|
| Report date: | 2-4-2015 |
| 3382014002R00 - NRC Website | |
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2014 002 00 1.0 DESCRIPTION OF THE EVENT On December 10, 2014, at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> with Unit 1 (U1) in Mode 1 at 100 percent power, station technicians commenced scheduled periodic channel calibrations of level transmitters for U1 Refueling Water Storage Tank (EIIS System - BP, Component - TK) Level Channel I instrument loop (1-QS-L-100C) and Channel II instrument loop (1-QS- L-100D). A pre-job brief was performed emphasizing one channel instrument loop calibration at a time. Initial job preparations were established for Channel I instrument loop (1-QS-L-100C) calibration. Test equipment was staged in the instrument rack room and at the U1 Refueling Water Storage Tank (RWST) level transmitter (EIIS Component - LT). The lead technician proceeded to the Main Control Room (EIIS System - NA) to brief the Operations Senior Reactor Operator (SRO). Required procedure step signatures were obtained and permission was granted to perform the Channel II calibration. At 1258 hours0.0146 days <br />0.349 hours <br />0.00208 weeks <br />4.78669e-4 months <br /> Operations entered the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action statement for Technical Specification (TS) for performance of the Channel II instrument loop (1- QS-L-100D) calibration.
Upon arrival to the instrument rack room the lead technician discovered Operations signatures were made in the test procedure for 1-QS-L-100D. At this time the test equipment was moved from the cabinet for 1-QS-L-100C to the cabinet for 1-QS-L- 100D. When it was identified that the procedure was for the 1-QS-L-100D task, the lead technician did not specifically communicate the change to the field team. Subsequently, 1-QS-L-100D was removed from service and placed in test. The lead technician remained in the instrument rack room while two technicians proceeded to the RWST level transmitter for field work activities. At this point technicians simultaneously verified they were on transmitter 1-QS-L-100C using the working copy of the procedure and began isolating and draining the level transmitter.
At 1344 hours0.0156 days <br />0.373 hours <br />0.00222 weeks <br />5.11392e-4 months <br />, RWST Channel I instrument loop (1-QS-L-100C) level indication failed low with Channel II instrument loop (1-QS-L-100D) level transmitter having already been removed from service. Operations personnel responded by entering abnormal procedure 1-AP-3, Loss of Vital Instrumentation. Additionally, TS 3.0.3 was entered due to two channels inoperable that affect Recirculation Spray (RS) pump (EIIS System - BE, Component - P) auto-start capability. At 1356 hours0.0157 days <br />0.377 hours <br />0.00224 weeks <br />5.15958e-4 months <br />, both level indications returned to normal. At 1417 hours0.0164 days <br />0.394 hours <br />0.00234 weeks <br />5.391685e-4 months <br />, Channel II was declared operable and TS 3.0.3 was cleared. Had a Containment Depressurization Actuation (CDA) occurred during this time, accident mitigation may have been impacted. At 1439 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.475395e-4 months <br />, Channel I was declared operable.
North Anna Power Station Unit 1 05000338 2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS Had a CDA occurred during the period that Channels I & II were out of service the RS pumps would have started without sufficient suction inventory. The Main Control Room (MCR) Operators could promptly reset the CDA signal and manually shutdown the RS pumps to prevent any damage. When RWST level decreased to 60 percent the RS pumps would be manually started per procedure. As such, this event posed no significant safety implications.
In addition, a cross-tie is available to allow the Low Head Safety Injection pumps (EIIS System - BP, Component - P) to provide containment spray if the RS pumps are inoperable.
On December 10, 2014, at 1713 hours0.0198 days <br />0.476 hours <br />0.00283 weeks <br />6.517965e-4 months <br />, an 8-hour report was made per 10 CFR 50.72(b)(2)(v)(D) for a condition that could have prevented the fulfillment of a safety function to mitigate the consequences of an accident.
3.0 CAUSE The cause of the event was due to personnel error. Station technicians failed to assess risk associated with the RWST level channel calibration tasks. Inattention as a result of repetition and/or becoming complacent and overconfident with the job task caused the team not to use human performance tools to mitigate the errors. Had the correct rigor for the task been addressed the event could have been prevented.
4.0 IMMEDIATE CORRECTIVE ACTION(S) Channel II instrument loop (1-QS-L-100D) was returned to service by procedure and verified, a channel check was completed on the Main Control Room (MCR) board to verify proper indication. The TS Action of 3.0.3 was cleared.
Channel I instrument loop (1-QS-L-100C) was returned to service by procedure and verified, a channel check was completed on the MCR board to verify proper indication.
The TS Actions of 3.3.2.d and 3.3.2.i were cleared.
5.0 ADDITIONAL CORRECTIVE ACTIONS Completed interim actions included removing the qualifications of the individuals involved until remediation was conducted; performed a stand down to ensure lessons learned are integrated into the daily work activities and department standards and expectations were reinforced; and supervisors have increased oversight for pre-job briefs and are maintaining field presence to ensure high risk, error likely tasks are briefed adequately, barriers and defenses used and standards and expectations reinforced.
6.0 ACTIONS TO PREVENT RECURRENCE Remediation plans have been implemented for the individuals involved that addresses task risk recognition and standards outlined in MA-AA-100 Conduct of Maintenance and rigor for Nuclear Safety. A performance improvement plan will be implemented to address adherence to standards and expectations, risk assessment/ mitigation, lead technician roles, and management observations.
7.0 SIMILAR EVENTS None 8.0 ADDITIONAL INFORMATION Unit 2 continued operating in Mode 1, 100 percent power and was not affected by this event.