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| Entered date | Event description | |
|---|---|---|
| ENS 49055 | 21 May 2013 16:46:00 | On March 24, 2013, at 1009 EDT, while personnel were entering the torus compartment to perform planned maintenance activities via permanently installed plant ladder, the sensing line to transmitter 2E41-N062D was inadvertently bumped. (This) was confirmed to be the cause for an invalid torus high water level alarm and a HPCI (High Pressure Core Injection) pump suction swap. This resulted in the HPCI suction swapping from its normal lineup, condensate storage tank (CST), to the torus as designed. Once actuated the suction swap occurred as designed. The cause was attributed to the close proximity between an individual descending/ascending the fixed ladder and the affected sensing line in conjunction with a loose tubing restraint which made the line more sensitive to being bumped. After confirming that the actuation on high torus level was invalid, HPCI suction was realigned to the CST. The HPCI pump suction was subsequently realigned to the CST and the loose tubing restraints were tightened. The licensee notified the NRC Resident Inspector. |
| ENS 47416 | 5 November 2011 12:18:00 | Maintenance activities are being performed on the Hatch Nuclear Plant's Technical Support Center (TSC) Emergency Ventilation System starting on November 5, 2011 at 0900. These maintenance activities include the replacing the TSC HVAC cooling coils, condensing unit and controls. The maintenance activity will be worked 24 hours per day until completion. The scheduled completion date is November 10, 2011. During the time these activities are being performed, the TSC air handling unit, TSC condensing unit, TSC filter train and the fan unit for the TSC filter train will not be available for operation. As such, the TSC HVAC will be rendered non-functional during the performance of this work activity. If an emergency is declared requiring activation of the TSC during the time these work activities are being performed, then the contingency plans call for utilization of the TSC during the time of these work activities, as long as environmental and radiological habitability conditions allow. Procedure 73EP-EIP-063-0, Technical Support Center Activation, provides instructions to direct TSC management to the Control Room and TSC support personnel to the Simulator Building to continue TSC activities if it is necessary to relocate from the primary TSC so that TSC functions can be continued. This event is reportable per 10CFR50.72 (b)(3)(xiii) as described in NUREG-1022, Rev.1 since this work activity affects an emergency response facility for the duration of the evolution. The licensee notified the NRC Resident Inspector.
The TSC was returned to service at 1621 EDT. The licensee has notified the NRC Resident Inspector. Notified R2DO (Hopper). |
| ENS 45835 | 13 April 2010 09:40:00 | This report is being made under 10CFR50.73(a)(2)(iv)(B)(2). On February 23, 2010 at 1050 EST procedure 52PM-C71-001-0, RPS M/G Set System Preventative Maintenance, was being performed. During restoration of RPS Buses on Unit 1, only the Unit 1 required logic was reset. The Unit 2 logic was also required to be reset but was not. Procedure 52PM-C71-001-0, RPS M/G Set System Preventive Maintenance, did not clearly require the reset of both Unit 1 and Unit 2 logic. The procedure has been revised to make this requirement clear. Continuation of steps in the procedure required links to be closed which resulted in SBGT starting on Unit 1 and Unit 2 from Unit 2 logic. Unit 1 and Unit 2 Reactor Building ventilation isolated. This was not due to a valid signal. The automatic actuation of the standby gas treatment system (SBGT) and the isolation of Unit 1 and 2 secondary containment isolation dampers is considered an invalid actuation since the parameters that cause this actuation to occur had not been exceeded. For this reason the actuation is considered invalid and a report to the NRC is not required by 10CFR50.72(b)(3)(iv); however, because the secondary containment isolation signals affected containment isolation valves in more than one system (Unit 1 and 2 components affected) the event is reportable as required by 10CFR50.73(a)(2)(iv)(B)(2). A licensee event report (LER) is required, but can be a telephone notification as allowed by 10CFR50.73. In the case of an invalid actuation reported under 10CFR50.73(a)(2)(iv), other than actuation of the reactor protection system (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. The four Standby Gas Treatment (SBGT) fans auto started and both Unit 1 and Unit 2 reactor building and refueling floor normal ventilation systems automatically shutdown and isolated. The SBGT Initiation and the ventilation system shutdown were both complete actuations. The licensee notified the NRC Resident Inspector. |
| ENS 45148 | 23 June 2009 05:08:00 | (The reactor automatically scrammed) on a Main Turbine Trip >27.6% rated thermal power. The main turbine trip was due to reactor high level. Post scram, reactor level decreased to approximately -26 inches. Reactor water level was restored with the condensate system. Both reactor recirc pumps tripped as required on EOC RPT Logic when the main turbine tripped. Both pumps have been restarted. A Group 2 isolation was received at +3 inches reactor water level with all valves closing as required. Investigation as to the cause of the transient is underway. All rods inserted during the scram. No relief valves actuated during the transient. Decay heat is being removed via turbine bypass valves to the main condenser. The plant is within normal shutdown temperature and pressure limits. The electrical grid is stable and the plant is in a normal shutdown electrical lineup. The Group 2 has been reset. There was no effect on Unit 1. The licensee has notified the NRC Resident Inspector. |
| ENS 42537 | 1 May 2006 05:17:00 | The Unusual Event was declared due to a fire lasting greater than 10 minutes (after discovery) within the protected area. The fire was located on the Isophase Bus Duct near the Main Transformer. A load reduction to 80% rated thermal power is in progress on Unit 1. The fire was extinguished at 0450 with dry chemicals extinguishers." The licensee believes the fire was on cabling in the Isophase bus duct due to overheating. The licensee has been monitoring hot spots on the duct cabling for several days. The fire did not apparently impact any other systems and observers are at the location monitoring for any change in conditions. No Tech Spec Limiting Conditions of Operations resulted from the fire and there is no impact on Unit 2 operations (which is currently at 100%). Termination criteria will be based on management judgment and safety assessment.
Unusual Event terminated at 0655 (EDT). Fire extinguished. Reactor power reduction continuing. Management evaluating continued operation. The unit is currently at 77% power and plans are to reduce power to 60% pending their evaluation of continued operation. The licensee will notify the NRC Resident Inspector. Notified R2 DO (K. Landis), NRR EO (M.J. Ross-Lee), IRD Manager (P. Wilson), DHS (S. York), and FEMA ( M. Roland). |