10 September 2017
Au cours du dépannage d’une jauge de pression, l’opérateur a trouvé une concentration d’hydrogène de 4 %, soit une valeur supérieure à la limite basse d’explosivité. Le titulaire ventile le bâtiment afin que le personnel de maintenance puisse y accéder et réparer la fuite. Les pompiers sont en attente. La déclaration du problème est faite suite à la fuite d’un gaz toxique. Deux heures et douze minutes après le début du problème, l’urgence a été levée car la fuite a été isolée et le taux d’hydrogène est retombé à 0%.
Type : PWR - Puisssance : 3 650 MWth - Première divergence : 1 / 1986 -
Available in english only
Event Number: 53005
Facility: MILLSTONE - State: CT Unit: [3] - RX Type: [3] W-4-LP
Event Date: 10/09/2017 - Event Time: 14:05 [EDT]
Emergency Class: UNUSUAL EVENT 10 CFR Section: 50.72(a) (1) (i) - EMERGENCY DECLARED
Initial PWR : 100 % Current PWR : 100 %
Event Text
NOTIFICATION OF UNUSUAL EVENT - FLAMMABLE GAS IN THE TURBINE BUILDING
While troubleshooting a hydrogen differential pressure gauge, operators found a hydrogen concentration greater than the lower explosive limit (4% hydrogen concentration). The licensee evacuated the turbine building. The licensee is ventilating the area to allow personnel access to isolate and repair the leak. The plant Fire Brigade is on standby.
This event was declared for GU-2: release of toxic or flammable gas.
The main generator pressure and hydrogen concentration are stable.
The licensee notified the NRC Resident Inspector.
Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
* * * UPDATE AT 1630 EDT ON 10/9/2017 FROM NORMAN KUZEL TO MARK ABRAMOVITZ * * *
The unusual event was terminated at 1617 EDT because the leak was isolated and the hydrogen concentration in the Hydrogen Control Cabinet was zero percent.
The licensee notified the NRC Resident Inspector.
Notified the R1DO (Jackson), IRD MOC (Stapleton), NRR (King), DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2017/20171010en.html