12 février 2018
Les missiles pourraient heurter les évents des cuves à mazout des groupes diesels principaux d’urgence des réacteurs 2 et 3. Ce problème remet en cause le fonctionnement des groupes durant une tornade. Des mesures compensatoires non précisées ont été mises en oeuvre.
Type : Fukushima 1 (BWR Mark 1) - Puissance : 2 957 MWth - Première divergence : n° 1 : 1 / 1970 - n° 2 : 1 / 1971 -
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Event Number : 53204
Facility : DRESDEN - State : IL
Unit :   - RX Type :  GE-3, GE-3
Event Date : 02/12/2018 - Event Time : 12:00 [CST]
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(ii)(B) - UNANALYZED CONDITION 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR Current PWR 2 N Y 100 Power Operation 100 Power Operation 3 N Y 100 Power Operation 100 Power Operation
UNANALYZED CONDITION FOR TORNADO GENERATED MISSILES
"On February 12, 2018, during evaluation of protection for Technical Specifications (TS) equipment from the damaging effects of tornado generated missiles, Dresden Station identified a non-conforming condition in the plant design such that specific TS equipment is considered to not be adequately protected from tornado generated missiles. Tornado generated missiles could strike the Unit 2, Unit 2/3, and Unit 3 Emergency Diesel Generator main fuel oil tank vents. This could result in crimping of the vents, which would affect the ability of the main fuel oil tanks to perform their function if a tornado would occur.
"This condition is reportable in accordance with 10 CFR 50.72(b)(3)(ii)(B) as a condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety and 10 CFR 50.72(b)(3)(v)(D) as a condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.
"This condition is being addressed in accordance with NRC enforcement guidance provided in Enforcement Guidance Memorandum (EGM) 15-002, ’Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance,’ and DSS-ISG-2016-01, ’Clarification of Licensee Actions in Receipt of Enforcement Discretion’ per Enforcement Guidance Memorandum EGM 15-002, ’Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance,’ Revision 1. Compensatory measures have been implemented in accordance with these documents.
"The NRC Resident Inspector has been informed of this notification."