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Des accidents nucléaires partout

Etats-Unis : Nebraska : Inondations et perte de refroidissement de la piscine de combustible usé du réacteur




9 juin 2011


Le réacteur nucléaire à eau sous pression de Fort Calhoun, à 20 miles au nord d’Omaha, dans le Nebraska est en état d’urgence en raison d’inondations imminentes de la rivière Missouri. Le lendemain, survenait un incendie d’origine électrique nécessitant une évacuation de la centrale. Le 8 juin, la CNRC a confirmé que l’incendie avait entraîné la perte de refroidissement de la piscine de combustible usé du réacteur.

Available in english only.


"On June 6, 2011, the Fort Calhoun pressurized water nuclear reactor 20 miles north of Omaha, Nebraska entered emergency status due to imminent flooding from the Missouri River. A day later, there was an electrical fire requiring plant evacuation. Then, on June 8th, NRC event reports confirmed the fire resulted in the loss of cooling for the reactor’s spent fuel pool.

The discussion includes specific details of the technical failures at Fort Calhoun, the risks of coolant loss at overcrowded “spent” fuel pools, and the national hazards of nuclear facilities along the Missouri and Mississippi Rivers, and other water sites during the current period of floods and climate change."

https://www.radio4all.net/index.php/program/52367


Event Text

FIRE IN THE WEST SWITCHGEAR ROOM

"At 0940 CDT an alert (HA 2, EAL 1) for operating Mode less than 210 degrees F [was] declared for a fire affecting the operability of plant safety systems required to establish or maintain safe shutdown. Time of fire was 0930 CDT. Control room received multiple alarms [and] 480 V bus 1B4A amps were observed to be oscillating. Bus 1B4A was secured [and] buses 1B3A and 1B3A-4A were lost. Halon activated properly. [At] 0956 CDT all notifications to applicable personnel were completed. At 1000 CDT 4160v buses 1A2 / 1A4 were secured to facilitate fire fighting. Spent fuel pool cooling was lost [as a result of the de-energized busses and the licensee] entered AOP-36 for loss of SFP cooling. Heat up rate [was] determined by STA. Current time to boil for SFP is 88.3 hrs. Spent fuel pool cooling is currently back in service. This condition is being reported pursuant to 10 CFR 50.72(a)(1)(i) for declaration of an emergency class specified in the licensee’s approved emergency plan."

Plant was in AOP-1 for flood mitigation. The fire is not believed to be flood related. Plant remains in AOP-1.

At about 0930 CDT the licensee noted fire in the west switchgear room. The fire brigade responded and found a room filled with smoke but no active fire. Halon did discharge in the room. At 0956 CDT, offsite assistance was called and Blair Fire Department responded to the site. Blair Fire Department confirmed no active fire in the switchgear room. All offsite power remained available as well as the emergency diesel generators if needed. The licensee is currently attempting to ventilate the room. A thorough inspection of the affected area and determine the caused of the electrical fault will be facilitated once the room has been fully ventilated.

The licensee has notified appropriate State and local government. The licensee notified the NRC Resident Inspector. A media or press release is also anticipated.

* * * UPDATE FROM ROBERT KROS TO HOWIE CROUCH AT 1313 EDT ON 6/7/2011 * * *

"Entered Alert for HA 3, EAL 1 access to a vital area (Switchgear and Turbine Building basement) due to toxic gases present from the fire in the West Switchgear room."

The licensee entered HA 3 at 1144 CDT. Their exit criteria is that the switchgear room is cleared for unimpeded access.

The licensee has notified the NRC Resident Inspector. Notified the R4IRC (Kennedy)

* * * UPDATE FROM ROBERT KROS TO WILLIAM HUFFMAN 1421 EDT ON 6/7/11 * * *

At 1315 CDT, Fort Calhoun Nuclear Station has exited Alert HA 2, EAL. It has been confirmed that no fire remained in the vital area. Plant shutdown cooling remained in-service and spent fuel pool cooling was restored and temperature verified to be lowering. The licensee has also exited Alert HA 3, EAL 1 after it was confirmed that the environmental conditions from the event and associated Halon discharge does not affect the ability to safely operate or safely shutdown the reactor due to being in Mode 5 and shutdown cooling remaining in-service. Fort Calhoun remains in Unusual Event HU 1, EAL 5 for River Level greater than 1004’ elevation as reported under EN #46929.

The licensee has notified appropriate State and local government. The licensee has also notified the NRC Resident Inspector. The NRC made notifications of the event termination to DHS, FEMA, DOE HHS and USDA.

https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2011/20110608en.{html


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