On April 30, 2018, the NRC announced that the agency has launched a special inspection into the circumstances surrounding voids in the residual heat removal system at the Watts Bar nuclear plant, which made the system inoperable for a time on both Unit 1 and Unit 2.
The plant, which is operated by the Tennessee Valley Authority (TVA), is located near Spring City, Tennessee—approximately 60 miles southwest of Knoxville.
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.
The NRC inspectors are reviewing the sequence of events, drawings, calculations and acceptance criteria; walking down portions of the plant’s systems; evaluating TVA’s response; and, assessing the adequacy of actions to address the causes of the issues.
A report documenting the results of the inspection should be issued within 45 days of the completion of the inspection.
On April 19, 2018, TVA informed the NRC that calculation revisions had reduced the acceptable size of a void due to gases in the system.
On April 21, 2018, the accumulated gas in the Unit 1 system was found to have exceeded the acceptable value.
On April 22, 2018, the same observation was made on Unit 2.
For additional information, please contact Roger Hannah at (404) 997-4417 or Joey Ledford at (404) 997-4416.