Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 55560 | 3 November 2021 18:05:00 | On 11/03/2021 Columbia Generating Station concluded the results for refueling outage 24 (R24) and 25 (R25) Local Leak Rate Testing as-found data was incorrect. At 1231 PDT on November 3rd, 2021 Columbia Generating Station determined the local leak rate tests (LLRT) for the X- 25B containment penetration did not meet Technical Specification requirements for LLRT acceptance criteria. The incorrect LLRT data identified for residual heat removal (RHR) B Suppression Pool Spray containment isolation valve (RHR-V-27B) was from the previous two refueling outages (R24 on 5/22/2019 & R25 on 6/512021) at which time primary containment was not required to be operable. The corrected leakage assigned to the X-25 penetration also resulted in total Type B and C leakage summation exceeding the maximum allowable leakage rate for the primary containment (1.0 La) for R24 and exceeding 0.6La in R25. The valve was flushed and retested satisfactory prior to entering the mode of applicability. This event is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(ii)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 54113 | 12 June 2019 12:17:00 | A contract employee supervisor had a confirmed positive test for alcohol during a random fitness-for-duty test. The employee's access to the plant had been terminated. The NRC Resident Inspector has been notified. |
| ENS 51182 | 26 June 2015 04:38:00 | At 2200 PDT during startup from refueling outage 22, it was discovered that both level instruments used in reactor protection system (RPS) trip system 'A' for initiation of a reactor scram on low reactor pressure vessel (RPV) level were observed to have failed high. This resulted in the inability to generate a full reactor scram on low level (+13 inches). All remaining RPV level indications demonstrated that level was being maintained within normal operating bands. This constitutes a condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to shut down the reactor. The RPS trip logic at Columbia consists of two trip systems, RPS trip system 'A' and RPS trip system 'B'. There are two level instrument channels in each trip system. Columbia utilizes a 'one-out-of-two taken-twice' trip logic to generate a full scram signal. At least one channel in both trip systems must actuate to generate a full scram signal. With both level instruments in RPS system 'A' failed high, the RPS trip logic was unable to generate a full scram. At 2246 (PDT) and in accordance with TS LCO 3.3.1.1 Condition C, a half scram was generated on RPS trip system 'A' to restore full scram capability. The cause of the failure of the two level instruments associated with RPS Trip system 'A' is under investigation. The level channels are being calibrated prior to changing to mode 1 (power operations). The licensee will notify the NRC Resident Inspector. |
| ENS 51094 | 28 May 2015 03:35:00 | A planned outage of the Division 2 medium voltage switchgear (SM-8) was initiated at 22:17 PDT on 5/27/15. The bus outage results in all area radiation monitors required for emergency classification being non-functional. Compensatory measure monitoring equipment has been established prior to the loss to provide alternate means of monitoring area radiation levels. The SM-8 outage window is scheduled to last 124 hours. Although the monitoring function is maintained by the compensatory monitoring equipment, the planned loss of area radiation monitors for greater than 72 hours is being reported as a major loss of emergency assessment capability in accordance with 10 CFR 50. 72(b )(3)(xiii). The NRC Resident Inspector has been notified. |
| ENS 49834 | 17 February 2014 10:42:00 | Reactor Building (Secondary Containment) pressure rose above the Technical Specification Surveillance requirement of 0.25 inches vacuum water gauge multiple times from 0044 (PST) to 0305 (PST) on 2/17/14. The alarm was received in the control room at 0305 (PST). This is reportable as an event that could have prevented fulfillment of a safety function needed to control the release of radiation and mitigate the consequences of an accident. Reactor Building pressure has been restored to normal (greater than 0.25 inches of vacuum water gauge), returning Secondary Containment to operable status. Highest actual value indicated was +0.21 inches pressure water gauge. The cause of the event is under investigation. There were no radiological releases associated with the event. The NRC Resident Inspector has been notified. |
| ENS 49700 | 7 January 2014 16:07:00 | At 1210 PST on January 7, 2014 the Reactor Building Stack Radiation Monitor- Intermediate Range detector was declared non-functional due to scheduled maintenance on supporting equipment. The monitor is expected to be out of service for approximately 1 hour. Preplanned compensatory actions have been implemented. This event is being reported as a loss of emergency assessment capability in accordance with 10 CFR 50.72(b)(3)(xiii). At 1238 PST on January 7, 2014 the Reactor Building Stack Radiation Monitor -Intermediate Range detector was declared functional following scheduled maintenance on supporting equipment. Emergency Assessment Capability has been restored. Preplanned compensatory actions have been secured. The licensee has notified the NRC Resident Inspector.
Licensee is retracting this event notification based on the following: Regulatory guidance in NUREG-1022 Revision 3 allows for not reporting EP equipment outages that are planned (i.e., maintenance) when outage time is not expected to exceed or does not exceed 72 hours, and when there are viable compensatory measures in place. Verification of the Control Room Logs indicates Columbia had viable compensatory measures in place during the maintenance outage and the outage duration was less than 72 hours. Columbia met the conditions in NUREG-1022; therefore, this event did not represent a loss of emergency assessment capability. The licensee has notified the NRC Resident Inspector. Notified R4DO (Allen). |
| ENS 49626 | 12 December 2013 12:44:00 | This notification is being made due to a loss of emergency assessment capability in accordance with 10 CFR 50.72(b)(3)(xiii). At 0436 (PST), on 12/12/2013 the Division 1 sample rack for monitoring primary containment oxygen and hydrogen atmospheric concentrations was removed from service for planned maintenance activities. The Division 1 sample rack is expected to be out of service for 14 hours. The redundant Division 2 sample rack was previously removed from service for maintenance and remains out of service for repairs. Compensatory measures to monitor primary containment for hydrogen and oxygen are available via grab samples using chemistry procedures. The licensee has notified the NRC Resident Inspector.
Following completion of maintenance activities, the Division 1 sample rack for monitoring primary containment oxygen and hydrogen atmospheric concentrations was returned to operable status at 1150 PST on 12/13/2013, restoring its required emergency assessment capability. The NRC Resident Inspector has been notified. Notified R4DO (Walker). |
| ENS 49631 | 13 December 2013 19:44:00 | On December 13, 2013 it was determined that a reportable condition has existed at Columbia Generating Station since 1500 hours (PST) on November 25, 2013. At 1500 hours on November 25, 2013, the Control Room Envelope (CRE) was declared inoperable based on the inability to ensure that the Control Room Emergency Filtration (CREF) System would be able to maintain a positive differential pressure with all areas surrounding the CRE boundary. Columbia does not have the installed instrumentation to directly monitor the differential pressure between the Main Control Room (MCR) and certain areas adjacent to the MCR. The pressure in the adjacent areas is controlled by placing conservative limits on allowed breach size for these adjacent areas. On November 25, 2013, it was identified that the combined breach size associated with several doors in these adjacent spaces resulted in exceeding the allowed limit. Based on exceeding the allowed breach size limit to the adjacent areas, the Control Room Envelope was declared inoperable, and Technical Specification Action Statement 3.7.3.B.1 was entered. An additional breach was discovered on 12/05/13 from a hole in ductwork passing through the cable spreading room, which is one of the adjacent areas to the CRE boundary, and that condition was added to the existing action statement 3.7.3.B.1. These are conditions that could have prevented fulfillment of a safety function of structures that are needed to mitigate the consequences of an accident and are reportable under 10 CFR 50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector.
In the case of this event, the Control Room Envelope (CRE) was declared inoperable and Technical Specification Action Statement 3.7.3.B.1 was entered conservatively based upon limited knowledge at the time of discovery. There is no installed differential pressure indication between the CRE and this area adjacent to the Main Control Room (MCR), therefore conservatively this adjacent area is included in the CRE, and leakage is administratively controlled. The leakage between the MCR and the adjacent area included in the CRE exceeded this administrative limit. Testing performed on November 20, 2013, prior to the December 13, 2013 reported events, as well as testing after the event, January 10, 2014, has demonstrated that the leakage identified does not prevent the Control Room Envelope (CRE) from establishing and maintaining the required differential pressure to ensure fulfillment of its required safety function for Control Room Habitability. The ability of the Control Room Emergency Filtration (CREF) system to perform its function of pressurizing and maintaining the Main Control Room positively pressurized with respect to its surroundings was not lost due to the leaking doors and duct specified in the event. Performance of the surveillance without these breaches sealed validated this conclusion. The event described above should not have been reported, as the Control Room Envelope was always operable and capable of fulfilling its safety function with the existing breaches and did not constitute a reportable event as conditions that could have prevented fulfillment of a safety function of structures that are needed to mitigate the consequences of an accident under 10 CFR 50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector. Notified the R4DO (Spitzberg). |
| ENS 49332 | 9 September 2013 07:11:00 | Scheduled maintenance of the Technical Support Center (TSC) / Operations Support Center (OSC) HVAC system for maintenance on the Air Handler (AMA-AH-S1) recirculation fan, outside air duct heater, and thermostat will start at approximately 0400 hours PDT on 09/09/13 and will last approximately 40 hours (estimated time from equipment tag out back to OPERABLE). During this time the TSC and OSC will not be available for use to support emergency response activities. Established compensatory measures direct Emergency Response Organization (ERO) members normally responding to either of these facilities to respond to alternate locations. No other emergency response facilities are impacted by the scheduled TSC / OSC Facilities HVAC maintenance work. This event is being reported as a loss of emergency preparedness capabilities in accordance with 10 CFR 50.72(b)(3)(xiii). The resident inspector has been notified. A follow up notification will be made when HVAC maintenance to the TSC / OSC Facilities has been completed and operability of these EP Facilities has been restored. * * * UPDATE FROM VERLE KESZLER TO PETE SNYDER AT 0823 EDT ON 9/15/13 * * * Scheduled maintenance of the Technical Support Center (TSC) / Operations Support Center (OSC) HVAC system is completed. The HVAC system has been returned to service and declared functional at 05:05 PDT on 9/15/13. The licensee has notified the NRC Resident Inspector." Notified R4DO (Hay). |