7 août 2014
La dégradation de ces murs serait suffisante pour empêcher la résistance au feu de 3 heures prévue dans les prescriptions. En cas d’incendie, les deux voies d’accès de sûreté pour l’arrêt pourraient être compromises. En attendant la restauration des murs pare-feu, en plus de la détection automatique d’incendie, d’autres mesures ont été prises pour corriger les conditions dégradées.
Type : Fukushima 1 (Type Mark 1) - Puissance : 2 804 MWth - Première divergence : 09/1974
Available in english only.
Event Number : 50351
Facility : HATCH
State : GA - Unit : [1] - RX Type : [1] GE-4
Event Date : 08/07/2014 - Event Time : 17:07
Emergency Class : NON EMERGENCY 10 CFR Section : 0.72(b)(3)(ii)(B) - UNANALYZED CONDITION
Initial PWR : 100 % - Current PWR : 100 % -
Event Text
UNANALYZED CONDITION DUE TO DISCOVERY OF DEGRADED FIRE BARRIER WALLS
"During a fire inspection activity involving inspection of fire walls that serve as Appendix R barriers, degradation of some fire walls was identified that was sufficient to prevent these walls from meeting Appendix R requirements as 3-hour fire barriers. In the event of a postulated fire in the affected areas, both safe shutdown paths on the affected unit could be compromised. Given this information, the determination was made that this condition meets the reporting criteria of 10CFR50.72(b)(3)(ii)(B).
"Compensatory measures were already in place in accordance with the plant’s Fire Hazard Analysis (FHA) as a result of previous conditions involving degraded penetrations in these same fire areas. The presence of the compensatory measures in addition to automatic fire detection in these fire areas ensure that the safe shutdown paths are preserved until the degraded conditions can be corrected.
"Condition Reports : 850802, 850819"
In addition to automatic fire protection features, the licensee has posted fire watches as a compensatory measure.
The licensee has notified the NRC Resident Inspector.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140808en.html