Trip of one main circulation pump

Kozloduy NPP, 1 July 2010

Nuclear Facility: Unit 5, Kozloduy NPP
Date:29.06.2010 Time:14:22

Event Title: Trip of one main circulation pump

Event description:

On 29.06.2010, Unit 5 runs on 100 % power. At 14:22 one of the four main circulation pumps switches off. The systems automatically reduce the Unit 5 power to 66%. The pump is electrically isolated and defining of the cause of its failure is initiated. The checks revealed that the pump switched off due to loss of information from two out of three brakers of the main steam bypass valve, which stops the steam flow to the turbine. The brakers were replaced, the power of the unit is reduced to 30% of the nominal and the pump has been started. At 2:45 on 30.06.2010 was started an increasing of the power.

A commission for investigation of the causes and elimination of the failure has been appointed.

 
INES rating of the event 0
*The final assessment by the NRA on the level of the event according to INES is announced following the receipt of the final report on the results from the investigation and the analysis of the event, according to art.12 of the Regulation for notification.

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