The following information was provided by the licensee via email:
This 60-day telephonic notification is being made in lieu of a licensee event report submittal as allowed by 10 CFR 50.73(a)(1). This notification is made pursuant to 10 CFR 50.73(a)(2)(iv)(A) to provide information pertaining to an invalid engineered safety feature actuation signal.
On September 6, 2022, at Waterford 3, while performing a plant protection system (PPS) power supply check, technicians observed an abnormally high voltage output. When the technicians opened the PPS bay cabinet door to adjust the voltage, they then observed low voltage indications. The direct cause of this issue is believed to be vibration induced relay chattering or an intermittent connection issue when opening the rear doors of PPS cabinets. This resulted in half the logic being met for the Engineered Safety Feature Actuation Signal (ESFAS) signals to fully actuate. The ESFAS signal opened the following valves: EFW-228A (EFW to SG 1 Primary Isolation), EFW-229A (EFW to SG 1 Backup Isolation), EFW-228B (EFW to SG 2 Primary Isolation) and EFW-229B (EFW to SG 2 Backup Isolation). This was a partial actuation of ESFAS. Affected plant systems functioned successfully.
The inadvertent actuation was caused by a spurious signal and was not a valid signal resulting from actual parameter inputs. The 1992 Statements of Consideration define an invalid signal to include spurious signals including jarring of a cabinet door. In accordance with
10 CFR 50.73(a)(1) a telephone notification is being made in lieu of submitting a written licensee event report. The NRC Senior Resident Inspector has been notified. These events did not result in any adverse impact to the health and safety of the public.
