Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 54064 | 15 May 2019 02:21:00 | At 2151 CDT, on 14 May 2019, Comanche Peak Nuclear Power Plant (CPNPP) experienced a voltage transient within the onsite 138kV switchyard due to the loss of one of the offsite switchyards supplying power to the CPNPP 138kV switchyard. The reduction in safeguards bus voltage due to the transient caused the Unit 2 safeguard busses to load shed and perform a slow transfer to power supplied from 345kV transformer XST2A. 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 by design. All AFW pumps have been returned to standby status. All other safety systems functioned as designed. Unit 1 is currently defueled, and was unaffected by this event. The licensee has notified the NRC resident inspector. |
| ENS 52817 | 21 June 2017 16:25:00 | During the review of an electrical circuit coordination calculation to support an ongoing revision of the Fire Safe Shutdown Analysis (FSSA), a lack of appropriate circuit protection coordination was identified in the coordination of electrical protective devices on 118 VAC electrical panels operating in bypass mode of operation. One or more of these electrical panels could be lost for various 10 CFR Appendix R III.G.2 fires outside the Control Room at CPNPP (Comanche Peak Nuclear Power Plant) due to circuit coordination issues. This could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10 CFR 50 Appendix R. Immediate compensatory actions are being taken to establish (or confirm already existing) fire watches in the Fire Areas containing the associate circuits which can potentially jeopardize the FSSA. This condition is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition. The NRC Resident Inspector has been notified.
On 06/21/2017 Comanche Peak reported an ENS Report (no. 52817) related to the potential loss of 118 VAC electrical panels operating in bypass mode of operation for various 10 CFR (50) Appendix R III.G.2 fires outside the Control Room due to circuit coordination issues. This could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10 CFR 50 Appendix R. Subsequent analysis by Engineering has determined that the affected panels remain coordinated for fire generated faults and can be credited as available by the Fire Safe Shutdown Analysis for a fire outside of the Control Room. Based on the above, the condition described in the ENS report no. 52817 is not considered to be an unanalyzed condition as described in 10 CFR 50.72(b)(3)(ii)(B). The licensee notified the NRC Resident Inspector. Notified R4DO (Azua). |
| ENS 51871 | 19 April 2016 19:54:00 | While performing a monthly check source on radiation monitor 1-RE-2328 (Main Steamline 1-04 Radiation Detector), the monitor was determined 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 1-04 could neither be evaluated nor monitored. This unplanned condition is reportable as a major 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 main steamline 1-04 N16 Radiation Monitor for early signs of a steam generator tube leak/rupture, pre-brief radiation protection technicians on taking local readings with a geiger-mueller tube on main steam line 1-04 and reporting the reading to the Control Room. Corrective actions are being pursued to restore 1-RE-2328 to functional status. The NRC Resident Inspector has been notified. |
| ENS 50955 | 5 April 2015 13:55:00 | At 0852 CDT on 04/05/2015, a partial loss of the 25kV Plant Support Power Distribution System caused a loss of both the Primary and Backup Meteorological Towers at Comanche Peak Nuclear Power Plant. Loss of both Meteorological Towers constitutes a major loss of emergency assessment capabilities in regard to meteorological conditions. The 25kV Plant Support Power Distribution System feeds certain non-safety related equipment and does not affect plant operation. An investigation into the cause of the loss of power is in progress. The licensee informed the NRC Resident Inspector. |
| ENS 50773 | 28 January 2015 11:38:00 | The Comanche Peak Primary Emergency Operations Facility (EOF) will be unavailable during planned maintenance on the EOF ventilation system. On January 28, 2015, CPNPP (Comanche Peak Nuclear Power Plant) began planned work to improve the reliability of the EOF ventilation system. The EOF will be unavailable for approximately three weeks. During the time the primary EOF is unavailable, the affected ERO members will respond to the Backup EOF in Granbury, Texas for any declared emergency event. Therefore, it is expected that appropriate assessment of plant conditions, notifications, and communications could still be made, if required, during the time the primary EOF is unavailable. The extended unavailability of the primary EOF is being reported in accordance with 10CFR50.72(b)(3)(xiii), which is any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability. The NRC Resident (Inspector) has been notified. A follow-up ENS communication will be made when the primary EOF availability is restored.
The availability of the Comanche Peak Primary Emergency Operations Facility (EOF) has been restored following planned maintenance on the EOF ventilation system. On January 28, 2015, CPNPP (Comanche Peak Nuclear Power Plant) began planned work to improve the reliability of the EOF ventilation system. The unavailability of the primary EOF was reported in accordance with 10 CFR 50.72(b)(3)(xiii). This report serves as a follow-up to Event Number 50773. The licensee notified the NRC Resident Inspector. The R4DO (Okeefe) was notified. |
| ENS 48318 | 18 September 2012 11:58:00 | On September 18, 2012, power was removed from SCADA A of the Radiation Monitoring System (RMS) to perform a planned system modification. During this period, data for most Unit 1 radiation monitors will not be electronically available in the emergency response facilities and will not be supplied to the Emergency Response Data System (ERDS), if activated. System alarms and data displays will still be available to the plant operators in the Control Room. The expected duration of RMS remote data partial inoperability is approximately 72 hours. The loss of Unit 1 remote readout capability requires compensatory measures to be used for the acquisition of radiological data in the emergency response facilities. These compensatory measures have been communicated to the emergency response organization, Therefore, it is expected that appropriate assessment of plant conditions, notifications, and communications could still be made, if required, during the time that the portions of the RMS are inoperable. This report is being made in accordance with 10 CFR 50.72(b)(3)(xiii), which is any event that results in a major loss of emergency assessment capability, offsite response capability, or offsite communications capability. An update message will be provided when the RMS is restored." The NRC Resident has been notified.
The Radiation Monitoring System alarms and data displays have been restored to the Comanche Peak Emergency Response Facilities (ERFs) following completion of planned system modifications. The emergency assessment capability of the Comanche Peak ERF have been re-established. The licensee has notified the NRC Resident Inspector. Notified the R4DO (Geoffrey Miller) |