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| Entered date | Event description | |
|---|---|---|
| ENS 56625 | 17 July 2023 14:13:00 | The following information was provided by the licensee email: At 0339 CDT on May 17, 2023, diesel generator 3 (DG3) had an auto-start during a surveillance test of excess flow check valves in containment atmosphere instrument sensing lines. During the surveillance, workers failed to recognize residual pressure in the system from the test. Per procedure, MS-PS-47C (main steam pressure switch) was placed back in service, resulting in initiation logic for both the high pressure core spray (HPCS) system and DG3 auto-start. Because the HPCS system was tagged out of service for maintenance it did not actuate. The auto-start of DG3 was an expected response to the high drywell pressure indication. The signals cleared, and DG3 was shutdown per procedure. As indicated in 10 CFR 50.73(a)(1), in the case of an invalid actuation reported under 10 CFR 50.73(a)(2)(iv)(A), the licensee may, at its option, provide a telephonic notification to the NRC Operations Center within 60 days of discovery of the event instead of submitting a written licensee event report. This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) for invalid actuations reported under 10 CFR 50.73 (a)(2)(iv)(A). This actuation was invalid since it was caused by programmatic issues in quality of procedural guidance and not the result of actual plant conditions warranting auto-start of DG3. The actuations were not initiated in response to actual plant conditions, this was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation. Therefore, this event has been determined to be an invalid actuation. Diesel generator 3 system responded as designed to the actuation signal. The HPCS system did not actuate since it was tagged out of service. There was no impact on the health and safety of the public or plant personnel. The following information is provided as specified in NUREG-1022: (a) The diesel generator 3 was actuated. (b) The actuation of DG3 was complete. (c) The DG3 train was started and functioned successfully. The NRC Resident Inspector has been notified. |
| ENS 55682 | 1 January 2022 17:35:00 | The Licensee provided the following information via fax: During performance of a surveillance of the High Pressure Core Spray (HPCS) service water system on January 1, 2022, the HPCS system was declared inoperable for performance of the surveillance. During the surveillance, pump discharge pressure and flow were above the action range curve specified in the surveillance. For the given flow rate, pump discharge pressure was too high. This condition prevents declaring the HPCS service water system and HPCS system operable. The HPCS service water and HPCS systems remain inoperable. The station entered Technical Specification (TS) 3.7.2.A and TS 3.5.1.B at 0910 (PST) on January 1, 2022. In accordance with TS 3.5.1.B, the Reactor Core Isolation Cooling (RCIC) system was verified to be operable. TS 3.5.1 Action B provides a 14-day completion time to restore HPCS to an operable status. All other Emergency Core Cooling systems (ECCS) are operable. This event is being reported as an event or condition that could have prevented the fulfillment of a safety function credited for mitigating the consequences of an accident per 10 CFR 50.72(b)(3)(v)(D). The HPCS system is a single train system at Columbia. The NRC resident has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee is investigating the cause of the high pump discharge pressure and verifying instrumentation accuracy.
This Notification is to retract EN 55682, Unplanned High Pressure Core Spray (HPCS) Inoperability. On 1/1/2022 at (1735 EST), Columbia Generating Station notified the NRC under 10 CPR 50.72(b)(3)(v)(D) of the inoperability of a single train of safety system (HPCS) for performance of the surveillance. During the surveillance pump discharge pressure and flow were above the action range curve specified in the surveillance. Engineering performed an analysis of this event and concluded the HPCS was operable during the event and would have performed its required safety function. The results of initial IST testing of HPCS-P-2 via OSP-SW/IST-Q703 on 01/01/22 resulted in measured parameters falling outside of the acceptable range specified for this pump. Systematic error was suspected as the cause of the failure and the test was reperformed following taking actions to eliminate the suspected systematic errors. The second performance of the test on 01/01/22 resulted in acceptable pump performance. Evidence exists that the initial performance of the test failed due to imprecise averaging techniques due to difficulties in averaging continuously changing values on the test instrument. The second performance of OSP-SW/IST-Q703 should be considered a successful test and the test of record as the systematic error was eliminated and measured parameters are considered valid. The NRC Resident Inspector has been notified. The HOO notified R4DO (Rolando-Otero). |
| ENS 55425 | 23 August 2021 23:20:00 | On August 22, 2021, Columbia Generating Station determined that no more than approximately eight (8) gallons of silicone oil was inadvertently released into a plant service water system due to a failed heat exchanger on a plant installed air compressor. The plant service water system returns water to a water basin that contains at a minimum 300,000 gallons of water. The water basin is connected to the Columbia River via a blowdown line. Although not confirmed, it is suspected that an unknown quantity of silicone oil may have been released to the Columbia River. A visual inspection of the basin did not identify any oil sheen or film, and there are no additional actions needed to mitigate this issue. It does not appear the oil release poses a threat to human health or the environment, however because there could have been a discharge of an unknown quantity of silicone oil into the Columbia River this matter is immediately reportable under RCW 90.56.280 to the US Coast Guard National Response Center and Washington State Department of Ecology. This condition is being reported pursuant to 10 CFR 50.72(b)(2)(xi) for news release or notification of other government agencies concerning an event related to the health and safety of the public or protection of the environment. Notifications to off-site agencies were performed at 1825 PDT on 8/23/2021. The NRC resident has been informed. |
| ENS 54630 | 1 April 2020 19:07:00 | A licensed operator had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified. |
| ENS 52276 | 3 October 2016 16:49:00 | On October 3, 2016, at 1008 PDT a Reactor Building Exhaust Valve (REA-V-1) unexpectedly closed, which caused the Technical Specification (TS) for secondary containment pressure boundary to not be met. The duration of time that the secondary containment TS was not met was approximately 4 minutes. Secondary containment differential pressure was restored within TS requirement of greater than or equal to 0.25 inches of vacuum water gauge at approximately 1012 PDT by manually starting Standby Gas Treatment (SGT) system (SYS) A. The cause of the REA-V-1 closure is currently under investigation. This condition is being reported under 10CFR50.72(b)(3)(v)(C) for an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. The licensee has notified the NRC Resident Inspector. |