Etats-Unis : Prairie Island : Indisponibilité des lignes d`alimentation

Source : http://www.sortirdunucleaire.org/Etats-Unis-Prairie-Island-indisponibilite
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d’urgence par les diesels de secours
3 juin 2014
Etats-Unis : Prairie Island : Indisponibilité
des lignes d’alimentation électrique
d’urgence par les diesels de secours
Indisponibilité des deux diesels d’alimentation d’urgence du réacteur n° 1. Malgré cette
défaillance, le réacteur a été maintenu à pleine puissance. Un contournement du défaut a
été obtenu 1h après sa découverte pour un diesel et 1h54 pour le second diesel.
Type : PWR - Puissance : 1 677 MWth - Première divergence : 12/1973
Available in english only.
Number : 50170
Facility : PRAIRIE ISLAND - State : MN - Unit : [1] - RX Type : [1]
Event Date : 06/03/2014 - Event Time : 19:02
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100 % Current PWR : 100 %
Event Text
DIESEL GENERATORS DECLARED INOPERABLE DUE TO NOT MEETING HIGH ENERGY LINE
BREAK REQUIREMENTS
"D1 and D2 Emergency Diesel Generators (DG) were declared inoperable at 1902 CDT due to the
station identifying that the Turbine Building HELB [High Energy Line Break] heatup analysis
temperature of 270 F exceeded the maximum temperature limit of 200 F for both diesel generators
supply and exhaust fan blade positioners.
"LCO 3.8.1 Condition B was entered for both DGs and LCO 3.8.1 Condition E was entered for two DGs
inoperable on the same unit. The DGs could start and run if required at the time of entry.
"This condition is reportable per 10 CFR 50.72(b)(3)(v) as an event or condition that could have
prevented the fulfillment of a safety function.
"Unit 1 continued to operate in Mode 1 at 100% power while bypasses were being put in-service to fail
the diesel generators supply and exhaust fan blade positioners in the full cooling mode to allow the
LCO conditions to be exited.
"At 2002 CDT the bypasses were installed on the D1 Diesel Generator Supply and Exhaust Fan Blade
Positioners therefore LCO 3.8.1 Condition E was exited for both D1 and D2 Emergency Diesel
Generators being inoperable. In addition LCO 3.8.1 Condition B was exited for D1 Diesel Generator
due to it being declared Operable.
"At 2056 CDT the bypasses were installed on the D2 Diesel Generator Supply and Exhaust Fan Blade
Positioners therefore LCO 3.8.1 Condition B was exited for D2 Diesel Generator due to it being
declared Operable.
"At no time was the health and safety of the public threatened.
"The Senior NRC Resident has been notified."
http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140604en.html