Federal inspectors are investigating an incident that left the Clinton nuclear power plant in Clinton, IL, without an emergency diesel generator in service during a refueling outage last month.
A three-member team from the Nuclear Regulatory Commission (NRC) will review the sequence of events and the plant’s analysis, determine the probable causes, evaluate shutdown procedures and assess the corrective actions taken.
The team will spend time on and off site. After the inspection, a report documenting the team’s findings will be issued and made public.
According to NRC regulations, at least one emergency diesel generator must be operable during a refueling outage. Emergency diesel generators are safety-related systems designed to provide power to the site if there is a loss of offsite power, said the agency.
NRC officials reported that during the May outage, plant workers removed each emergency diesel generator from service one at a time to perform maintenance. However, as they were working on the second unit, a plant worker discovered the first generator was not completely restored to operating status. Once the issue was identified, workers took immediate action to restore a diesel generator to operable service as required by regulations, said the agency.
Plant spokesman Gabe Goldsmith said officials are continuing to investigate the situation.
“Exelon Generation is committed to operating our nuclear fleet at world-class levels of safety, reliability and performance excellence,” he said. “During Clinton’s 2018 spring refueling outage, operators discovered that two of the three of the station’s emergency diesel generators were inoperable for a brief period of time while workers were performing maintenance. Site leaders took immediate action to restore the generators to service, notify the NRC and put in place rigorous corrective actions to address this issue going forward. The NRC began a special inspection of this issue on June 20, and we look forward to demonstrating how our team’s response was effective to ensure safety.”
The plant has been receiving increased NRC oversight since last year due to a finding of low to moderate safety significance involving an issue with an emergency diesel generator room ventilation fan.