ENS Event | |
|---|---|
18:39 Aug 7, 2023 | |
| Title | 60-DAY Optional Telephonic Notification for an Invalid Specified System Actuation |
| Event Description | The following information was provided by the licensee via phone and email:
At 1439 EDT on August 7, 2023, a spurious level spike on the unit 4 reactor coolant system (RCS) level instrument (4-RCS-LT160A, 'Hot Leg 1 Level') caused actuation of containment isolation, reactor trip, automatic depressurization system (ADS) stage 4, and in containment refueling water storage tank (IRWST) isolation signals. The spurious level changes caused an invalid signal based on the incidental response of the 4-RCS-LT160A instrumentation due to water spray that was being used for reactor vessel cleaning (being performed prior to initial fuel loading). The level fluctuations resulted in engineered safety features actuation signals (containment isolation, ADS stage 4, and IRWST isolation signals) and a reactor trip signal, with the reactor trip signal already present. Three containment isolation valves closed due to the containment isolation signal that was generated. These valves were: 4-CAS-V014, 'instrument air supply containment isolation, air-operated valve,' 4-SFS-V034, 'spent fuel pool cooling system suction header containment isolation, motor-operated valve,' and 4-SFS-V035, 'spent fuel pool cooling system suction header containment isolation, motor-operated valve.' The other automatic containment isolation valves were either already closed at the time of the event or properly removed from service. All affected equipment functioned properly. The other actuation signals that were observed during this event (ADS stage 4, IRWST isolation, and reactor trip) did not result in any equipment changing position or automatically operating (i.e., the actuation signals occurred while the systems were properly removed from service). Units 1, 2, and 3 were not affected. This event did not result in any adverse impact to the health and safety of the public. The NRC Resident Inspector was notified. |
| Where | |
|---|---|
Vogtle  Georgia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1409.83 h58.743 days <br />8.392 weeks <br />1.931 months <br />) | |
| Opened: | William Garrett 12:29 Oct 5, 2023 |
| NRC Officer: | Karen Cotton-Gross |
| Last Updated: | Oct 6, 2023 |
| 56779 - NRC Website
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WEEKMONTHYEARENS 567792023-08-07T18:39:0007 August 2023 18:39:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-DAY Optional Telephonic Notification for an Invalid Specified System Actuation ENS 453922009-09-20T22:00:00020 September 2009 22:00:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation from a Surveillance Activity Test Signal ENS 451732009-06-07T02:46:0007 June 2009 02:46:00 10 CFR 50.73(a)(1), Submit an LER Invalid Containment Ventilation Isolation System Actuation 2023-08-07T18:39:00 | |