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| Entered date | Event description | |
|---|---|---|
| ENS 55305 | 12 June 2021 23:57:00 | At time 2227 CDT on 06/12/21, Main Steam Line 2-01 Radiation Monitor 2-RE-2325 was declared to be non-functional. With this radiation monitor non-functional, all of the emergency action levels for a steam generator tube rupture in Steam Generator 2-01 could neither be evaluated nor monitored. This unplanned condition is reportable as a loss of assessment capability per 10 CFR 50.72(b)(3)(xiii). Comanche Peak Nuclear Power Plant (CPNPP) has assurance of steam generator integrity and fuel cladding integrity. Compensatory measures are in place to assure adequate monitoring capability. Radiation Protection technicians have been briefed on taking local readings with a Geiger-Mueller tube on MSL 2-01. Corrective actions are being pursued to restore 2-RE-2325 to functional status. The NRC Resident Inspector has been notified. |
| ENS 55304 | 12 June 2021 22:00:00 | At time 1725 CDT on 06/12/21, Main Steam Line 2-03 Radiation Monitor 2-RE-2327 was declared to be non-functional. With this radiation monitor non-functional, all of the emergency action levels for a steam generator tube rupture in Steam Generator 2-03 could neither be evaluated nor monitored. This unplanned condition is reportable as a loss of assessment capability per 10 CFR 50.72(b)(3)(xiii). Comanche Peak Nuclear Power Plant (CPNPP) has assurance of steam generator integrity and fuel cladding integrity. Compensatory measures are in place to assure adequate monitoring capability. Radiation Protection technicians have been briefed on taking local readings with a Geiger-Mueller tube on MSL 2-03. Corrective actions are being pursued to restore 2-RE-2327 to functional status. The NRC Resident Inspector has been notified. |
| ENS 54329 | 15 October 2019 19:10:00 | At time 0911 (CDT), Main Steamline Radiation Monitor 2-RUK-2325/2327 (MAIN STEAM LINE 2-01/2-03 RADIATION MONITOR) was removed from service for planned maintenance. Compensatory measures were in place prior to removing the monitor from service to assure adequate monitoring capability available to implement the CPNPP emergency plan in the unlikely event of challenges to the steam generator or fuel cladding. The N16 radiation monitor serves as a backup with alarm function and Radiation Protection technicians have been briefed on taking local readings with a Geiger-Mueller tube on MSL (Main Steam Line) 2-01 and MSL 2-03. With this radiation monitor non-functional, with compensatory measures in place, and the monitor NOT expected to be returned to service within 72 hours, the condition is reportable as a loss of assessment capability per 10CFR50.72(b)(3)(xiii). Comanche Peak Nuclear Power Plant (CPNPP) has assurance of steam generator integrity and fuel cladding integrity and there is negligible safety significance to the current condition with respect to the public health and safety perspective. Corrective actions are being pursued to complete maintenance and restore 2-RUK-2325/2327 to functional status. The NRC Resident Inspector has been notified. |
| ENS 53767 | 3 December 2018 11:15:00 | At 0315 (CST) on 12/3/18, the Comanche Peak Nuclear Power Plant experienced a loss of 138 KV transformer XST1. Unit 1 is currently at 100% power. Unit 2 was subjected to actuation of both blackout sequencers causing an automatic start of both motor driven Auxiliary Feedwater (AFW) pumps as well as the turbine driven AFW pump. No emergency diesel generators started as per design. Train A and B motor driven and the turbine driven AFW pumps have been returned to automatic. All other safety systems functioned per design. The loss of power to 138 KV transformer XST1 resulted in loss of power to both safeguards busses on Unit 2. The busses performed a load-shed and slow transfer to power supplied from 345 KV transformer XST2A as designed and were re-energized and loads sequenced back onto the busses. The emergency diesel generators are not required to start unless the busses are not re-energized by the alternate offsite transformer. All electrical power related actuations functioned as designed. There was no impact on Unit 1. The licensee has notified the NRC Resident Inspector. |
| ENS 53550 | 14 August 2018 02:18:00 | At 23:58 (Central Daylight Time) Unit 2 Reactor Tripped (automatic reactor trip) due to a Turbine Trip/ Generator Lock Out. All Auxiliary Feedwater Pumps started due to steam generator Lo Lo levels. Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IP0-007B. The Emergency Response Guideline Procedure Network has been exited. Decay heat is being rejected to the Main Condenser via Steam Dump Valves. The cause of the Generator Lockout is currently under investigation. All control rods fully inserted in response to the automatic reactor trip. The licensee notified the NRC resident. |