1er août 2014
Ce circuit d’injection comporte un retour de test pour le réservoir de stockage des condensats. Lors de l’injection de sécurité, des vannes ferment ce circuit de retour pour assurer l’injection vers le cœur. Ces vannes ont été identifiées fuyardes et l’inventaire de l’eau de la piscine ne serait pas suffisant pour assurer l’injection pour les durées établies. Ce problème impose l’arrêt du réacteur.
Type : BWR Mark 3 - Puissance : 3 091 MWth - Première divergence : 10/1985
Available in english only.
Event Number : 50337
Facility : RIVER BEND
State : LA - Unit : [1] - RX Type : [1] GE-6
Event Date : 08/01/2014 - Event Time : 21:42
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100 % Current PWR : 100¨%
Event Text
HIGH PRESSURE CORE SPRAY DECLARED INOPERABLE DUE TO TEST RETURN VALVE LEAKAGE
"River Bend Station personnel declared the High Pressure Core Spray system inoperable at 2142 [CDT] on 8/1/2014.
"The High Pressure Core Spray (HPCS) system at River Bend Station includes a test return line to the Condensate Storage Tank (CST). The test return line is isolated by two motor operated valves (MOVs) with both having a safety function to close on an ECCS [Emergency Core Cooling System] initiation signal to ensure that injection flow is directed to the reactor vessel. While the HPCS pump is normally aligned to the CST, the credited source of water for the pump is the suppression pool. Accordingly, the pump suction is realigned to the suppression pool on low level in the CST or when suppression pool level rises to a certain point. Station personnel identified leakage past the test return valves to the CST. In evaluating this condition, engineering personnel noted that the observed leakage past the two MOVs might be sufficient to deplete suppression pool inventory such that it would not be capable of performing its specified function for the duration of the 30 day mission time. The issue of concern is that once HPCS is aligned to the suppression pool post-LOCA, pool inventory would be lost to the CST through the leaking test return valves.
"Based on that concern, the HPCS pump suction valve from the suppression pool was disabled in the closed position to preserve pool inventory. This action caused the HPCS system to be declared inoperable at 2142 [CDT]. This action results in a 14 day shutdown LCO and is reportable to the NRC in accordance with 10 CFR 50.72(b)(3)(v)(D).
"The HPCS pump remains available with its suction aligned to the CST. Assuming normal makeup water supplies are available, the HPCS system can be realigned to the suppression pool if necessary.
"This condition continues to be evaluated and rework options are being developed.
"The NRC Senior Resident Inspector has been notified."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140804en.html
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