ENS 50370
ENS Event | |
|---|---|
23:31 Aug 14, 2014 | |
| Title | Unit 2 Technical Specification Required Shutdown Due to Multiple Inoperable Emergency Diesel Generators |
| Event Description | While performing scheduled maintenance on Unit 2 Emergency Diesel Generator (EDG) 2-2, Diablo Canyon Power Plant (DCPP) identified a failed capscrew on engine cylinder 1L. As part of subsequent inspections to determine whether a similar condition existed on any of the other Unit 1 or Unit 2 EDGs, a degraded capscrew was identified on EDG 2-3 cylinder 8L at 1631 PDT on 08/14/2014. No capscrew issues were identified on the Unit 1 EDGs or on Unit 2 EDG 2-1. Although all operational tests of the diesels up to the time of discovery were satisfactorily performed with no indication of degraded performance, the EDG 2-3 was declared inoperable.
Because two Unit 2 EDGs were inoperable concurrently, this is being reported as a condition that could have prevented fulfillment of a safety function per 10 CFR 50.72(b)(3)(v). Per the requirements of TS 3.8.1, with two EDGs inoperable, a plant shutdown was commenced at 2031 PDT on 08/14/2014. Therefore, this condition is also being reported in accordance with 10 CFR 50.72(b)(2)(i). Offsite power remained available throughout this condition. EDG 2-2 remains out of service as part of its scheduled maintenance window. This condition did not result in any adverse impact on the health and safety of the public. A press release is planned. The licensee informed the NRC Resident Inspector. The licensee also reported event notifications for 10 CFR 50.72(b)(3)(v)(C) - Control of Rad Release and 10 CFR 50.72(b)(3)(v)(D) - Accident Mitigation. The licensee plans to continue the shutdown to Mode 3 and is developing plans to return one of the two inoperable EDGs to operable status by the time the unit reaches Mode 5. |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
| Time - Person (Reporting Time:+1.8 h0.075 days <br />0.0107 weeks <br />0.00247 months <br />) | |
| Opened: | Jeremy Cobbs 01:19 Aug 15, 2014 |
| NRC Officer: | Jeff Rotton |
| Last Updated: | Aug 15, 2014 |
| 50370 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (63 %) |