The U.S. Nuclear Regulatory Commission in March completed an inspection at Exelon's Limerick nuclear generating station, which included a review of the plant's activities, procedures, records and an interview of personnel.
The inspection examined the plant's activities related to safety and compliance with the NRC's rules, regulations and conditions of the facility's license.
The inspection also reviewed the plant's identification of an unattended locked high radiation area on April 14 that prompted NRC officials on April 25 to determine whether a contract radiation protection technician serving as a guard intentionally left the locked area unattended.
"Based on testimonial and documentary evidence gathered during the investigation, the NRC concluded that while a violation of a technical specification requirement occurred, the NRC was unable to substantiate that the contract radiation protection technician deliberately left LHRA boundary unattended," NRC officials wrote in a letter to Exelon. "The safety significance of the violation was evaluated by the NRC and was found to be Green because the area was under constant camera surveillance coverage with a qualified health physics technician observing this area of the drywell from the remote monitoring system."
A report that followed the inspection documents one Severity Level IV violation of NRC requirements and two non-cited licensee-identified violations "determined to be of very low safety significance," the NRC letter states.
"The violation stems from a failure by Exelon to formally notify the NRC Operations Center of the event in a prompt manner," NRC Public Affairs Officer Neil Sheehan said via email.