Another busy week at the NRC Event Reports page:
1. Monday afternoon, Unit 1 at the River Bend nuclear power plant in Louisiana shut down automatically after low condensor vacuum resulted in a turbine trip. Following the scram, water level in the reactor fell, causing the Reactor Protection System to switch on. Additionally, control room operators received a report of a fire in a manhole on the site. The station fire brigade was dispatched and a small fire in a cable tray was extinguished.
2. Tuesday afternoon, the sole unit at the Pilgrim nuclear power plant in Massachusetts had to be shut down manually as a result of “degrading main condensor vacuum.” After the scram, one train of the Standby Gas Treatment system, which should have switched off automatically following the reactor trip, failed to do so and had to be secured manually. Cause of the scram in under investigation.
3. Tuesday afternoon, Unit 3 at the Browns Ferry nuclear facility in Alabama suffered an automatic reactor scram follwoing the loss of a 500 KV power source. The Reactor Core Isolation System was activated to maintain water level in the unit. At the time of the incident, the reactor’s High Pressure Coolant Injection system was tagged out-of-service for maintenance. Power to the reactor was restored using alternative feeder breakers.
All three units at Browns Ferry (pictured above) and the one at Pilgrim are General Electric Mark I reactors of the same type as the reactors that melted down at Fukushima. (You can usually guess this from the now-familiar square blue containment structures.) The Browns Ferry reactors came online between 1972 and 1976. The Pilgrim reactor went into service in 1972.
And there were a pair of Fitness for Duty reports this week:
4. Last Friday, a licensed operator at Browns Ferry tested positive for alcohol during a random Fitness of Duty screening. (No relation, I’m sure, to item 3 above.) The operator’s “unescorted access” to the plant has been suspended.
5. And on Wednesday, in an incident that is short on detail, a licensed operator at the Dresden nuclear power plant in Illinois was denied access to the facility for “violating the company’s Fitness for Duty policy.” Hope they didn’t let him drive home.