The 39 year old reactor had been down for a period when it was included into the network again on Wednesday October 31 at 16:55. 23 hours later, at 16:02 on Thursday, a short circuit in turbine No. 2 triggered an automatic shutdown of the reactor.
Kola NPP says in a short note on its portal that no safety violations took place, and the background radiation at the nuclear power plant remains unchanged.
It is not clear what caused the short circuit in the turbine. Reactor No. 1 was commissioned in 1973 and is the oldest of the power plant’s four water-cooled reactors of the VVER-440 type.
Especially the two oldest reactors at Kola NPP have been criticized for lack of safety by both Nordic authorities and the International Atomic Energy Agency.