22 juillet 2014
Une des deux vannes du circuit de refroidissement du diesel a refusé de s’ouvrir. Ce refus d’ouverture a limité le débit de refroidissement, ne laissant pas de marge de sécurité de fonctionnement au groupe électrogène. Le relais découvert comme cause de cette panne a été remplacé.
Type : BWR Mark 2 - Puissance : 3 988 MWth - Première divergence : 05/1987
Availbale in english only.
Event Number : 50296
Facility : NINE MILE POINT - State : NY
Unit : [2] - RX Type : [2] GE-5
Event Date : 07/22/2014 - Event Time : 13:43
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100 % Current PWR : 100%
Event Text :
DIESEL GENERATOR FOR HIGH PRESSURE CORE SPRAY DECLARED INOPERABLE DURING SURVEILLANCE TESTING
"This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. During the conduct of the Unit 2 Division 3 High Pressure Core Spray (HPCS) Diesel Generator (DG) surveillance test, one of 2 Cooling Water Outlet Valves failed to automatically open. The Division 3 Diesel is supplied by two redundant trains of cooling water one from each Service Water Divisional Header. Although the redundant cooling water supply was fully available and supplied adequate cooling to the diesel generator, the DG was at reduced margin to have adequate cooling water supply, if required during a loss of offsite power. Due to this loss of margin and inoperable condition, it has been determined that this failure could potentially affect the safety function of this system, and is being reported as an 8 hour ENS notification."
The licensee has attributed the failure to high resistance in a relay which is currently being replaced. This places Unit 2 in the Technical Specification Action Station 3.8.1, which requires restoration of Diesel Generator within 72 hours or commence a Reactor Shutdown. All other ECCS Systems have been verified operable.
The licensee informed the NRC Resident Inspector and will inform the State of New York.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140723en.html