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| Entered date | Event description | |
|---|---|---|
| ENS 52363 | 13 November 2016 17:39:00 | At 1012 (CST), Unit 1 Main Steam Line 1-01 Radiation Monitor (1-RE-2325) failed high. With this radiation monitor non-functional, all of the emergency action levels for a steam generator tube rupture in steam generator 1-01 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 and there is a negligible safety significance to the current condition from a public health and safety perspective. Additionally, compensatory measures are in place to assure adequate monitoring capability is available to implement the CPNPP emergency plan in the unlikely event of challenges to the steam generator or fuel cladding. Until this radiation monitor can be restored, Operations has implemented compensatory measures to monitor the main steamline 1-01 N-16 (Nitrogen-16) radiation monitor for early signs of a steam generator tube leak/rupture and pre-brief radiation protection technicians on taking local readings with a Geiger-Muller tube on Main Steam Line 1-01 and reporting the reading to the Control Room. Corrective actions are being pursued to restore 1-RE-2325 to functional status. The NRC Resident Inspector has been notified. Radiation monitor 1-RE-2325 is not in the plant technical specifications but is important to safety and the Emergency Plan. |
| ENS 50713 | 2 January 2015 11:43:00 | At 0314 (CST) on 01/02/2015, a partial loss of the 25KV Power Distribution Systems caused a loss of both the Primary and Backup Meteorological Towers at the Comanche Peak Nuclear Power Plant. This resulted in a major loss of emergency assessment capabilities in regard to meteorological conditions. The 25 KV Plant Support Power Loop feeds certain non-safety-related equipment and does not affect plant operation. An investigation by Meter and Relay Technicians revealed no abnormal conditions/damaged equipment. The supply breaker was re-closed at 0915 on 01/02/2015. Power was restored to both Meteorological Towers and proper operation was verified. The licensee notified the NRC Resident Inspector. |
| ENS 49743 | 18 January 2014 12:18:00 | At 0840 (CST), Comanche Peak NPP (CPNPP) Unit 1 turbine tripped causing a reactor trip. All rods inserted. No evolutions were in progress at time of trip. The cause of the trip is under investigation. A Generator Negative Sequence Current High Alarm was received immediately prior to turbine trip. Both Motor Driven Auxiliary Feed Water Pumps and the Turbine Driven Auxiliary Feed Water Pump started in response to Steam Generator Lo-Lo Levels. Currently, Unit 1 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IPO-007A and the Emergency Response Guideline Procedure Network has been exited. Decay heat is being rejected to the Main Condenser via Steam Dump Valves (Turbine Bypass Valves). Normal plant response was observed and all systems actuated as expected. No radiological release is in progress. There was no impact to CPNPP Unit 2, and off-site power remains available. The licensee has notified the NRC Resident Inspector. |
| ENS 49497 | 2 November 2013 01:44:00 | At 2147 CDT on 11/1/2013, Unit 2 Reactor tripped during Solid State Protection System Slave Relay Testing. This test utilizes a blocking circuit to verify the operability of the slave relay which trips the Main Turbine and both Main Feedwater pump turbines, on a Hi-Hi Steam Generator level or Safety Injection. No valve actuation is expected to occur. While positioning the Slave Relay switch in a testing lineup, the relay actutated. The Unit 2 Turbine tripped as well as both Main Feedwater Pumps. The Turbine Trip actuated the Reactor Trip since power was above 50%. The trip of both Main Feedwater Pumps started both Motor Driven Auxiliary Feedwater Pumps. The Steam Generator Lo Lo Levels started the Turbine Driven Auxiliary Feed Water Pump. All systems responded as expected. Currently, Unit 2 is being maintained in Hot Standby (Mode 3) in accordance with Integrated Plant Operating Procedure IPO-007B and the Emergency Response Guideline Procedure Network has been exited. Decay Heat is being rejected to the Main Condenser via Steam Dump Valves (Turbine Bypass Valves). The licensee has notified the NRC Resident Inspector. |