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Etats-Unis : Prairie Island : les deux générateurs diesel d’urgence du réacteur n°2 en panne




31 janvier 2019


La panne est due à une température de l’air trop basse. Les diesels de secours du réacteur n° 1 sont disponibles et pourraient alimenter le réacteur n°2. Les source électriques extérieures étaient également disponibles. 28 minutes après la découverte du problème, les diésels sont redevenus opérationnels. La limite de température était de moins 35,5 °C.

Type : PWR - Puissance : 1 667 MWth - Première divergence : 12 / 1974 -

Available in english only


Event Number : 53853

Facility : PRAIRIE ISLAND - State : MN

Unit : [2] - RX Type : [2] W-2-LP

Event Date : 01/31/2019 - Event Time : 07:43 [CST]

Last Update Date : 01/31/2019 Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION

Initial PWR  : 100 % Current PWR  : 100 %

Event Text

BOTH EMERGENCY DIESEL GENERATORS INOPERABLE DUE TO LOW AIR TEMPERATURE

"At 0743 [CST] on 1/31/2019, both trains of Unit 2 Diesel Generators were declared INOPERABLE due to outside air temperature exceeding the low temperature design limit for the diesel engines ; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v) for an event or condition that could have prevented the fulfillment of a safety function. The Unit 2 Diesel Generators are still able to start if necessary to provide power. Additionally, multiple layers of defense in depth measures are in place to ensure safety. Prairie Island has five sources of offsite power ; all of which are currently available. The Unit 1 Diesel Generators are OPERABLE and capable of being cross-connected to Unit 2. Additional equipment capable of responding to beyond design basis events is available on site providing another layer of defense in depth.

"Both Unit 2 Diesel Generators were returned to an OPERABLE status at 0810 on 1/31/2019 based on outside air temperature rising above the low temperature design limit with forecasted temperatures to remain above the low temperature design limit.

"There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."

The air temperature limit was -30 degrees Fahrenheit.

Unit 1 was not affected. The EDGs were supplied by a different manufacturer with different air temperature limits.

https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2019/20190201en.html