14 août 2014
Alors que le générateur diesel d’urgence 2 - 2 était en arrêt pour maintenance, une tête de vis a été retrouvée sur un cylindre du moteur. Le 14 août, un contrôle sur le générateur 2 - 3 a également démontré la présence d’une vis sur un cylindre. Ce groupe a été déclaré hors service. Aucune tête de vis n’a été retrouvée sur les deux autres groupes. Deux groupes étant indisponibles en même temps, l’arrêt du réacteur a été engagé le 14 août, à 20h31. La source électrique extérieure est restée présente durant toute la durée du problème.
Type : PWR - Puissance : 3 411 MWth - Première divergence : 05/1985
Available in english only.
Event Number : 50370
Facility : DIABLO CANYON - State : CA -
Unit : [2] - RX Type : [2] W-4-LP
Event Date : 08/14/2014 - Event Time : 16:31
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(2)(i) - PLANT S/D REQD BY TS 50.72(b)(2)(xi) - OFFSITE NOTIFICATION 50.72(b)(3)(v)(A) - POT UNABLE TO SAFE SD 50.72(b)(3)(v)(B) - POT RHR INOP
Initial PWR : 100 % Current PWR : 63 %
Event Text
UNIT 2 TECHNICAL SPECIFICATION REQUIRED SHUTDOWN DUE TO MULTIPLE INOPERABLE EMERGENCY DIESEL GENERATORS
"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.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140818en.html#en50370
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