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| Entered date | Event description | |
|---|---|---|
| ENS 49031 | 14 May 2013 18:37:00 | During Refueling Outage 21, at 1502 PDT on 5/14/13, power to the Technical Support Center (TSC) and Operations Support Center (OSC) was removed as part of transferring the facility to temporary power during a bus outage impacting the normal facility power supply. The TSC and OSC will be unavailable for use for several hours until temporary power has been established. Established compensatory measures direct ERO members normally responding to either of the two impacted centers to respond to alternate locations. No other emergency response facilities are impacted by the bus outage. This event is being reported as a loss of emergency preparedness capabilities in accordance with 10 CFR 50.72(b)(3)(xiii). The resident inspector has been notified. A follow up notification will be made when temporary power has been established and the facility is available for use. The licensee has notified the NRC Resident Inspector. * * * UPDATE FROM SANDRA CHRISTIANSON TO PETE SNYDER AT 1637 EDT ON 5/15/13 * * * This is a follow-up courtesy notification to EN# 49031. Temporary power has been established to the TSC and OSC, and both are available for emergency response. Normal power to TSC and OSC is expected to be restored on or about June 2, 2013 at 0600 PDT and will require a similar removal of power to the facility. A separate notification will be made when swapping off of temporary power. The licensee has notified the NRC Resident Inspector. Notified R4DO (Hay).
On 5/31/13, power to the Technical Support Center (TSC) and the Operations Support Center (OSC) was removed as part of transferring the facility from temporary power back to the normal facility power supply. The duration of the power outage will last approximately 90 minutes. The TSC and OSC are unavailable for use during this time for support of emergency response activities. Established compensatory measures direct Emergency Response Organization (ERO) members to respond to alternate locations. No other emergency response facilities are impacted. This event is being reported as a loss of emergency preparedness capabilities in accordance with 10 CFR 50.72(b)(3)(xiii). The NRC Resident Inspector has been notified. A follow up notification will be made when normal power has been reestablished and the facility is available for use. Notified the R4DO (Azua).
At 1700 hours (PDT) on 5/31/13, normal power has been reestablished to the TSC and OSC, and both are available for emergency response. The licensee has notified the NRC Resident Inspector. The licensee notified the NRC Resident Inspector. Notified the R4DO (Azua). |
| ENS 46977 | 21 June 2011 18:40:00 | This event is reportable under 10 CFR 50.73(a)(2)(iv)(A) as an automatic actuation of general containment isolation signals affecting containment isolation valves in more than one system. This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) for invalid actuations reported under 10 CFR 50.73(a)(2)(iv)(A). This actuation was invalid since it was caused by maintenance activities and not by any actual plant condition warranting containment isolation. On April 23, 2011, at 0814 hours, during implementation of a clearance order for ongoing work, Reactor Protection System (RPS) Bus A was transferred from the normal to alternate power supply. The power transfer functions as a break before make, and the momentary loss of power caused an unexpected actuation of the Groups 3 and 4 outboard containment isolation valves. Outboard isolations occurred in the reactor building drain and ventilation systems, and reactor closed cooling systems. Control room emergency ventilation and standby gas treatment systems also started. All systems functioned as designed, excluding those components that were already removed from service. Following the event, the RPS Bus A was re-energized and the plant was restored to normal operating condition for the current configuration per plant procedures. The unexpected actuation was due to a latent design conflict between a new design modification and existing equipment that was not discovered until during the implementation phase of the modification. The subsequent investigation cited inadequate review and engagement in the design process by station personnel of the vendor supplied design change modification package as the cause. As part of the implementation of the modification package an interposing relay was introduced into the Nuclear Steam Supply Shutoff System (NSSSS) logic circuit. The work for this modification was performed on the two days prior to this event, April 21st and 22nd. The new design was such that the source of power for the added relay was the same power supply which supplied the alternate logic channel. The resulting condition created a scenario where loss of the RPS-A power supply would complete both halves of the NSSSS outboard trip logic. The design has been revised such that loss of RPS-A or RPS-B power supply will not result in loss of both halves of the NSSSS trip logic circuit. Planned corrective actions will enhance procedures to ensure key design parameters and performance objectives are established early in the design process. There were no actual safety consequences associated with this event since all affected equipment responded as designed. The NRC Resident Inspectors have been notified. |
| ENS 46972 | 20 June 2011 13:30:00 | This event is reportable under 10 CFR 50.73(a)(2)(iv)(A) as an automatic actuation of general containment isolation signals affecting containment isolation valves in more than one system. This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) for invalid actuations reported under 10 CFR 50.73(a)(2)(iv)(A). This actuation was invalid since it was caused by maintenance activities and not by any actual plant condition warranting containment isolation. On April 21, 2011, at 1310 hours, upon de-energization of the Reactor Protection System (RPS) Bus A for maintenance, an unexpected actuation of the Groups 3 and 4 outboard containment isolation valves occurred. Outboard isolations occurred in the reactor building drain and ventilation systems, and reactor closed cooling systems. Control room emergency ventilation and standby gas treatment systems also started. All systems functioned as designed, excluding those components that were already removed from service. Following the event, the RPS Bus A was re-energized and the plant was restored to normal operating condition for the current configuration per plant procedures. The subsequent investigation found that personnel involved with work planning and control did not recognize that de-energizing RPS Bus A would create a condition which completed the Nuclear Steam Supply Shutoff System outboard isolation logic. An associated relay for the second channel had been previously de-energized to support ongoing maintenance. The cause of allowing this conflicting work to occur was determined to be inadequate procedural guidance. Planned corrective actions will enhance procedures to identify logic impacts, conflicting equipment and recommended protection schemes. There were no actual safety consequences associated with this event since all affected equipment responded as designed. The NRC Resident Inspectors have been notified. |