A special inspection will be initiated into how an excess amount of gas is in the residual heat removal system used to help shut down the reactors at Tennessee Valley Authority’s (TVA) Watts Bar Nuclear Power Plant near Spring City, TN.
TVA informed the Nuclear Regulatory Commission (NRC) two weeks ago revisions to its initial calculations had reduced the acceptable size of a void due to gases in the system that helps cool down the Watts Bar reactors during their shut down.
On April 21, the accumulated gas in the Unit 1 system was found to have exceeded the acceptable value, and on April 22, the same observation was made on Unit 2.
NRC inspectors will review the sequence of events, drawings, calculations and acceptance criteria, walk down portions of the plant’s systems, evaluate TVA’s response and assess the adequacy of actions to address the causes of the issues.
The issue identified by TVA does not warrant having to shut down either of the Watts Bar units and a report on the onsite visit this week is expected by June, said NRC spokesman Roger Hannah.
The residual heat removal system is used to complete the plant’s cooldown process at lower pressures and also provides important functions during certain accident scenarios.
Both reactors at Watts Bar remain operating at full power.
“Both units at Watts Bar Nuclear Plant continue to operate safely, while we monitor the performance of our multiple, redundant plant safety systems,” said TVA spokesman Jim Hopson.