The Nuclear Regulatory Commission (NRC) said it will send an Augmented Inspection Team (AIT) to the single-unit, 1,200 MW Wolf Creek Nuclear Generating Station to review the circumstances surrounding an automatic reactor trip and loss of offsite power that occurred there on Jan. 13.
Just after 2 p.m. on Jan. 13, officials at the Wolf Creek Nuclear Operating Co., declared a Notice of Unusual Event after the failure of a main generator electrical breaker, followed by an unexplained loss of power to an electrical transformer. This caused the switchyard to become de-energized, which removed the plant’s connection to the electrical power grid. The emergency diesel generators automatically started and powered safety-related equipment.
At 5:09 p.m. on January 13, Wolf Creek terminated the Unusual Event after off-site power was partially restored. Plant personnel are continuing to investigate the cause of the failure and determine necessary repairs. There were no radiological releases due to the event.
NRC resident inspectors responded to the control room to monitor site activities during the event and were onsite a week after to monitor licensee activities and initial recovery actions.
In an emailed statement to Power Engineering magazine on Jan. 16, Wolf Creek spokesperson Jenny Hageman said plant operators were not speculating as to when the plant will be back online.
AIT’s are used by the NRC to review more significant events or issues at NRC-licensed facilities. The six-member team has assumed responsibility from the resident inspectors for gathering information about the shutdown event and will travel to the site in the coming weeks. The team will be led by NRC Region IV Branch Chief Mark Haire of the Division of Reactor Safety.
The team will put together a detailed chronology of the event, evaluate the adequacy of licensee actions in response to the incident and assess the impact of the prolonged loss of off-site power to non-safety related equipment. The team’s report will not contain inspection findings, but will identify areas for further inspection follow-up.
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