13 Jun (NucNet): The accidental closure of the main loop isolation
valve (MLIV) on a panel in the emergency control room was the cause of
a sudden decrease in power at unit 2 of the Dukovany nuclear power
plant in the Czech Republic on 3 June 2008.
The incident had no impact on the surroundings of the plant, on the local environment or the operation of the plant's three other units. There was no threat to nuclear or radiation safety.
Zbynek Grunda, technical international relations manager for plant operator CEZ, said the closure of the MLIV in turn caused a primary coolant flow decrease in loop 4, one of the unit's six independent reactor cooling loops which take away heat from the reactor via six steam generators.
Mr Grunda said the accidental closure of the MLIV was the result of human error. An instrumentation and control worker inadvertently knocked a lever, which sent a 'close' signal to the valve.
Unit operators monitored and controlled the situation, and all automatic emergency systems functioned as intended.
Dukovany-2 is a 412-megawatt pressurised water reactor unit. The other three units are also PWRs.
Related reports in the NucNet database (available to subscribers)
Czech Republic's Dukovany Sets Generating Record In Strong Nuclear Year (World Nuclear Review No. 6, 10 February 2007)
