ENS 54403
ENS Event | |
|---|---|
18:25 Nov 21, 2019 | |
| Title | |
| Event Description | EN Revision Imported Date : 1/13/2020
UNIT 1 HIGH PRESSURE CORE SPRAY INOPERABLE On 11/21/2019, at 1225 CST, as a result of Division 4 DC bus voltage oscillations, bus voltage lowered to less than the required improved technical specification (ITS) voltage of 127.6 VDC. This resulted in declaring High Pressure Core Spray (HPCS) system inoperable per technical specification LCO 3.8.4 and 3.8.9 actions. Division 4 DC bus voltage was restored to greater than 127.6 VDC at 1227 CST. The HPCS system remains inoperable due to Division 4 DC battery charger inoperability. Since HPCS is an emergency core cooling system and is a single train safety system, this condition is reportable under 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector has been notified. Clinton Power Station has implemented required compensatory actions due to the Division 4 DC battery charger and HPCS remaining inoperable.
The purpose of this notification is to retract a previous report made on 11/21/2019 (EN 54403) under 10 CFR 50.72(b)(3)(v)(D). Subsequent to the initial notification, the event and the NRC guidance in NUREG-1022 pertaining to 10 CFR 50.72(b)(3)(v)(D) were reviewed further. The evaluation determined that the Division 4 DC bus voltage oscillations were caused by a degraded but operable charger. The Division 4 battery remained fully charged during the event and its operability was not impacted. Therefore, the HPCS system remained Operable. Under these circumstances, this event does not represent an inoperability of an accident mitigation system under 10 CFR 50.72(b)(3)(v)(D). Therefore, EN 54403 is retracted. The NRC Resident Inspector has been notified. Notified R3DO (Hanna). |
| Where | |
|---|---|
Clinton  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+2.77 h0.115 days <br />0.0165 weeks <br />0.00379 months <br />) | |
| Opened: | Allen Brand 21:11 Nov 21, 2019 |
| NRC Officer: | Brian Lin |
| Last Updated: | Jan 10, 2020 |
| 54403 - NRC Website | |