The U.S. Nuclear Regulatory Commission (NRC) issued two “yellow” findings for Entergy’s Arkansas Nuclear One plant for a March 2013 fatal accident. A yellow finding is one of substantial safety significance.
Workers were moving a 525-ton component from the plant’s turbine building during a refueling outage when temporary lifting collapsed, causing the component to fall.
The falling equipment killed one worker, injured eight and caused damage to other nuclear plant equipment, which caused a loss of off-site power and a small explosion inside electrical cabinets. Unit 2 automatically shut down when a reactor coolant pump tripped due to vibrations caused by the heavy component hitting the turbine floor. Unit 1 was shut down at the time for refueling.
NRC resident inspectors responded to the site the day of the incident. A subsequent investigation determined that the lifting assembly collapse resulted from the licensee’s failure to adequately review the assembly design ad ensure an appropriate load test.
The NRC identified the preliminary red and yellow findings documented in a March 24 inspection report, but after a regulatory conference with Entergy officials in May and after considering the information provided by the licensee, NRC determined that yellow findings were appropriate.