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Category:Licensee Event Report (LER)
MONTHYEAR05000277/LER-2024-003, Automatic Reactor Scram Following Main Turbine Trip Due to Degraded Condenser Vacuum2024-09-0505 September 2024
Automatic Reactor Scram Following Main Turbine Trip Due to Degraded Condenser Vacuum
05000277/LER-2024-002, Uncoordinated DC Circuits Cause Unanalyzed Condition2024-04-0808 April 2024
Uncoordinated DC Circuits Cause Unanalyzed Condition
05000277/LER-2024-001, Automatic Reactor Scram Due to an Invalid Generator Lockout2024-03-21021 March 2024
Automatic Reactor Scram Due to an Invalid Generator Lockout
05000278/LER-2023-002, Main Steam Isolation Valves Stroke Times Exceed Technical Specification Limit2023-12-14014 December 2023
Main Steam Isolation Valves Stroke Times Exceed Technical Specification Limit
05000278/LER-2023-001, Standby Liquid Control Pump Inoperable for Greater than LCO Window Due to Gas Intrusion2023-11-0707 November 2023
Standby Liquid Control Pump Inoperable for Greater than LCO Window Due to Gas Intrusion
05000277/LER-2022-002, Automatic Depressurization System Safety Relief Valve Actuator Diaphragm Degraded2022-12-15015 December 2022
Automatic Depressurization System Safety Relief Valve Actuator Diaphragm Degraded
05000277/LER-2022-001, Automatic Reactor Scram Due to Loss of Power to Both RPS Buses2022-07-15015 July 2022
Automatic Reactor Scram Due to Loss of Power to Both RPS Buses
05000277/LER-2021-003, Manual Reactor Scram Due to Degrading Condenser Vacuum2022-01-12012 January 2022
Manual Reactor Scram Due to Degrading Condenser Vacuum
ML21196A4852021-07-16016 July 2021
LER 2-2021-002-00 for Peach Bottom Atomic Power Station, Unit 2, Safety Relief Valve Inoperability Due to Nitrogen Leakage from Braided Hose Wear
05000277/LER-2021-001, High Pressure Coolant Injection System Declared Inoperable Due to Instrument Power Inverter Failure2021-06-24024 June 2021
High Pressure Coolant Injection System Declared Inoperable Due to Instrument Power Inverter Failure
05000277/LER-2020-002, Degraded Condition Due to RPV Instrument Nozzle Leakage2020-12-22022 December 2020
Degraded Condition Due to RPV Instrument Nozzle Leakage
05000277/LER-2020-001, Emergency Diesel Generator Shutdown Due to Intercooler Low Pressure Results in Condition Prohibited by Technical Specifications2020-04-24024 April 2020
Emergency Diesel Generator Shutdown Due to Intercooler Low Pressure Results in Condition Prohibited by Technical Specifications
05000278/LER-2017-0012017-12-20020 December 2017
Reactor Pressure Boundary Leakage Due to Weld Failure in One-Inch Diameter Instrument Line, LER 17-001-00 for Peach Bottom Atomic Power Station (PBAPS), Unit 3 Regarding Reactor Pressure Boundary Leakage Due to Weld Failure in One-Inch Diameter Instrument Line
05000277/LER-2017-0012017-03-0808 March 2017
Emergency Diesel Generator Exhaust Stacks Nonconforming Design for Tornado Missile Protection, LER 17-001-00 for Peach Bottom Atomic Power Station (PBAPS), Unit 2 Regarding Emergency Diesel Generator Exhaust Stacks Nonconforming Design for Tornado Missile Protection
05000278/LER-2016-0012016-11-22022 November 2016
Leak in High Pressure Coolant Injection Drain Pipe Results in a Loss of Safety Function, LER 16-001-00 for Peach Bottom, Unit 3, Regarding Leak in High Pressure Coolant Injection Drain Pipe Results in a Loss of Safety Function
05000277/LER-2016-0012016-11-11011 November 2016
Leak in High Pressure Service Water Pipe Results in Condition Prohibited by Technical Specifications, LER 16-001-00 for Peach Bottom, Unit 2, Regarding Leak in High Pressure Service Water Pipe Results in Condition Prohibited by Technical Specifications
05000278/LER-2015-0012016-02-26026 February 2016
Loss of High Pressure Coolant Injection System Function as a Result of Failed Flow Controller Signal Converter, LER 15-001-00 for Peach Bottom, Unit 3, Regarding Loss of High Pressure Coolant Injection System Function as a Result of Failed Flow Controller Signal Converter
ML13058A0432013-02-22022 February 2013
Submittal of Independent Spent Fuel Storage Installation (ISFSI) Cask Event Report
ML1007702362010-03-12012 March 2010
60-Day Security Event Report 2-10-S01
ML0927401622009-09-30030 September 2009
LER 09-S01-00 for Peach Bottom, Units 2 & 3 Regarding Unescorted Access Granted to Contract Worker Who Did Not Provide Complete Work History Information
ML1015505682009-07-10010 July 2009
Event Notification for Peach Bottom on Elevated Tritium Levels Found in On-Site Well
ML0434503772004-12-10010 December 2004
LER-04-S01-00 for Peach Bottom Atomic Power Station (PBAPS) Unit 2 and Unit 3, 60 Day Security Event Report 2-04-S01
ML19095A7391976-12-0505 December 1976
Reporting Abnormal Occurrence No. 50-278-74-33 at Peach Bottom Atomic Power Station for Failure of Main Steam Line High Flow Switch dPIS-3-2-116C to Trip During Surveillance Test
2024-09-05
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Abstract
On 01/29/2024 at 1202 hours0.0139 days <br />0.334 hours <br />0.00199 weeks <br />4.57361e-4 months <br />, Unit 2 experienced a Generator lockout, Turbine trip and automatic Reactor Scram. All control rods inserted, and all safety systems responded as designed. Reactor level was initially maintained by Feedwater and pressure controlled with bypass valves. During the scram response, condenser vacuum degraded due to the loss of Turbine steam seals, resulting in level and pressure control being transferred to Reactor Core Isolation Cooling (RCIC) and High Pressure Coolant Injection (HPCI), respectively.
The cause of the Generator lockout is under investigation, with the suspected cause being a spurious trip of the Audio Tone system. The system has been removed from service with a redundant system providing the protective function. The Audio Tone system is scheduled for replacement in the 2024 refueling outage.
This event is reportable under 10CFR50.73(a)(2)(iv)(A) due to manual or automatic actuation of systems listed in 10CFR50.73(a)(2)(iv)(B) including the Reactor Protection System, containment isolation signals, actuation of an emergency core cooling system and Reactor Core Isolation Cooling. An ENS notification was made within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the event and was updated within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, reference ENS 56936.
(See Page 2 for required number of digits/characters for each block)
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/) Page 3 of 3 cooling system and RCIC. An ENS notification was made within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the event and was updated within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, reference ENS 56936.
Safety Consequences The reactor Scram occurred as designed and resulted in no safety consequences. All safety systems responded as expected. As described above, the temporary degradation in condenser vacuum resulted in use of the RCIC system to control level for a portion of the response, but this did not challenge the ability to safely shutdown and cool down the unit.
Corrective Actions Immediate corrective actions were taken to remove the affected Audio Tone system (TTR-1) from service and utilize the fully redundant TTR-2 system. The TTR-1 Audio Tone drawer has been replaced and a new set of cables has been identified and tested. After the completion of additional testing, this system will be maintained in a standby condition as a spare. The Audio Tone system is scheduled for a complete replacement in the upcoming 2024 refueling outage.
The corrective action to address the condenser vacuum degradation is to revise the procedure which sets the sealing steam pressure control valve to ensure it will receive the appropriate demand signal when needed.
Previous Similar Events Peach Bottom has not experienced a Scram due to a Generator lockout in at least 10 years. The station experienced a trip of the Audio Tone system for an offsite source due to cable degradation in 2001 (Ref. EN 38241).
