A 1000-megawatt unit of Bulgaria’s Kozloduy nuclear power plant underwent an emergency shutdown on September 1 2007, facility operators said.

The system automatically switched off the reactor.

The incident caused no radioactive leak, a statement from the Kozloduy power plant said.

Experts investigated what caused the shutting down. It is unclear what repairs are needed and when the unit will be in operation again.

Two other smaller units of the same type in the NNP were switched off on December 31 2006 due to safety concerns in the EU. The closure of the blocks was a preliminary condition for Bulgaria’s entry into the EU.