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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56284 | 23 December 2022 20:13:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Technical Specification Required Shutdown | The following information was provided by the licensee via email: At 1513 EST on 12/23/22, a Technical Specification required shutdown was initiated at the Davis-Besse Nuclear Power Station Unit 1. Technical Specification (TS) Action Limiting Condition of Operation (LCO) 3.7.9 for Ultimate Heat Sink water level minimum requirements was not met and condition 'A' was entered on 12/23/22 at 1412 EST with a required action to `Be in Mode 3' with a completion time of 6 hours and `Be Mode 5' with a completion time of 36 hours. This event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(i). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. At 1640 on 12/23/22, the NRC granted enforcement discretion for the shutdown requirements of TS LCO 3.7.9 and the shutdown was terminated with the unit remaining in Mode 1. | ||
| ENS 55734 | 5 February 2022 20:14:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Technical Specification Required Shutdown | The following information was provided by the licensee via email: At approximately 1402 EST on 2/5/2022, with the Unit in Mode 1 at approximately 98 percent power, Operations was performing a valve lineup and inadvertently isolated a portion of the Reactor Coolant System (RCS) Letdown System, resulting in the system relief valve lifting and entry into the Makeup and Purification System Malfunction Abnormal Procedure due to loss of letdown. Pressurizer level increased and Technical Specification (TS) Limiting Condition for Operation (LCO) 3.4.9 CONDITION A was entered at 1414 EST due to Pressurizer level not below the limit of 228 inches, which has a REQUIRED ACTION to restore Pressurizer level within one hour. A rapid plant down power was initiated at approximately 1430 EST to reduce Pressurizer level. At 1514 EST on 2/5/2022, TS LCO 3.4.9 CONDITION B was entered, which has a REQUIRED ACTION to place the Unit in MODE 3 in 6 hours and in MODE 4 in 12 hours. As the Unit was continuing to down power, this represents initiation of a Technical Specification required shutdown, and this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(i). At approximately 1542 EST the down power was stopped at 15 percent power. Pressurizer level was restored to less than 228 inches at approximately 1603 EST, and TS LCO 3.4.9 was exited. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. | Reactor Coolant System | |
| ENS 52079 | 1 July 2016 09:42:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Failure to Perform Technical Specification Required Shutdown | At 2342 (EDT), June 30, 2016, the Control Room received panel alarms associated with Safety Features Actuation System (SFAS) Channel 2. Subsequent investigation revealed the alarms were due to a loss of supplied power caused, in part, by a level permissive in the Borated Water Storage Tank (BWST) to be inoperable. With SFAS Channel 1 BWST level transmitter previously declared inoperable for maintenance, the on-shift operating crew did not correctly identify that technical specification (TS) 3.3.5, Condition B applied which is a 6-hour shutdown required action. At 0245, following a duty team call when the condition was re-assessed, the crew entered the proper additional Condition B and correctly identified they were approximately 3 hours into a 6-hour shutdown specification. At 0330 the condition was inappropriately exited on the premise that an operable but degraded situation could be justified. The plant did not initiate a shutdown required by technical specification but, in retrospect, should have initiated and completed a shutdown within 6 hours of 2342. On July 1 at 1351, the BWST level transmitter for SFAS Channel 1 was repaired and declared operable (and exited TS 3.3.5 Condition B), however, the total time exceeded the 6-hour shutdown action. The plant remained stable throughout this event. On July 9, 2016, while internally discussing the event among FENOC senior leadership, it was determined that a 4-hour report would have been made if the shutdown was initiated. Hence, this report is retrospective in that a 10 CFR 50.72(h)(2)(i) required report should have been made upon the initiation of any nuclear plant shutdown required by plant's technical specification. A Licensee Event Report will be provided pursuant to 10 CFR 50.73(a)(2)(i)(B) as a condition that was prohibited by the plant's technical specification. The NRC Resident Inspector has been notified. (At 1325 EDT on July 1, it was determined that the justification for SFAS channel 2 BWST level permissive to be operable but degraded could not be supported and reentered TS 3.3.5 Condition B.) | 05000346/LER-2016-008 | |
| ENS 41330 | 13 January 2005 14:49:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Entry Into Technical Specification Required Shut Down Due to Loss of Essential Bus | The following information was provided by the licensee via facsimile: At 0849 hours on January 13, 2005, during testing of Essential Bus D1 (Undervoltage Units monthly functional test) (the) Potential Transformer secondary fuse blew. This caused an Essential 4160 VAC Bus D1 undervoltage condition. Emergency Diesel Generator #2 auto started due to the undervoltage condition on Essential Bus D1. This auto start of EDG #2 is reportable IAW (in accordance with) 10CFR50.72(b)(3)(iv)(a). (The licensee entered) into Technical Specification 3.0.3 with a loss of Essential 4160 VAC Bus D1 (with) plant shutdown required within 1 hour if the Essential Bus and DC battery chargers 2P and 2N are not restored. At 0949 hours, (the licensee) commenced plant shutdown to comply with Technical Specification 3.0.3. The initiation of the plant shutdown is reportable IAW 10CFR50.72(b)(2)(i). (At) 1049 hours, (the license) re-energized Essential 4160 VAC Bus D1 and verified battery chargers 2P and 2N energized. (At)1051 hours, (the licensee) exited Technical Specification 3.0.3 and stopped plant shutdown. (The licensee also noted that) at 0855 hours, EDG #2 was shutdown when the #2 Service Water pump did not start. (At) 1144 hours, Service Water Pump #2 (was started and the licensee) declared Service Water Loop 2 OPERABLE. The license has notified the NRC Resident Inspector, will notify local government agencies, and expects to make a press release. | Service water Emergency Diesel Generator | 05000346/LER-2005-001 |