VERNON — Federal investigators say a Vermont Yankee staffer deliberately failed to check the functionality of employees' radiation-exposure monitors over the course of eight months in 2016.
Nuclear Regulatory Commission officials believe the monitors continued to operate properly due to backup software that would have detected any problems with the devices. They say the incident had “minor safety significance.”
But the federal investigation nevertheless spurred a violation notice issued June 26 by the NRC.
“Entergy must provide a written response detailing its corrective actions because the violation was willful and was not identified by the company,” NRC spokesman Neil Sheehan said.
Joe Lynch, a senior government affairs manager for plant owner Entergy, didn't immediately comment on the substance of the NRC's notice.
“We are reviewing the notice of violation and, as instructed by the NRC's letter, will be providing a response to the NRC no later than July 26, 2017,” Lynch said.
Entergy ceased power production at Vermont Yankee at the end of 2014. But there is still much radioactive material on site including the Vernon plant's spent nuclear fuel, most of which remains in a cooling pool inside the reactor building.
Plant staff are checked constantly for exposure to radioactivity. And a provision of the facility's protective program “requires the performance of daily response checks for personnel monitoring equipment,” NRC documents say.
But a federal investigation found that a senior radiation protection technician “deliberately did not perform those checks” while working night shifts at the plant between Jan. 19 and Sept. 20 of last year, documents show.
The employee, who wasn't identified by the NRC, no longer works for Vermont Yankee. It isn't clear whether the employee was dismissed or departed voluntarily.
The technician's documentation showed that the checks had been performed, and he or she denied falsifying records. But investigators found evidence to the contrary on the contamination monitors' hard drives, the NRC said.
In fact, officials say the technician didn't perform any of the required equipment checks until September - not long after federal investigators began interviewing Vermont Yankee staff about the issue.
Entergy started its own review in response to the federal probe, but the company didn't report the violation to federal regulators, documents say.
The NRC ultimately found that the technician's failure “did not affect the calibration or overall functionality” of the monitors. That's because the equipment has software that would “remove the components from service if issues with the detectors are identified,” and that didn't happen, officials wrote.
Because of such software, the current nuclear industry standard is to check the monitors weekly. Vermont Yankee, however, had retained more-stringent rules mandating daily checks, documents say.
The technician in question didn't work more than four consecutive nights, federal officials added. So the monitors never went a full week without being checked by someone else.
The violation is labeled a “severity level IV,” which is the least-severe in the NRC's classification system. There are no potential fines associated with such a violation, Sheehan said.
Still, federal officials noted that the violation “was committed with deliberate intent, and the NRC regulatory program is based, in part, on licensees and their employees acting with integrity.”
Entergy has a month to submit a written statement that either offers a reason for the violation or disputes it. The company also is expected to detail the steps it has taken and will take to correct the problem.
Vermont Yankee administrators also received a severity level IV violation last year for withdrawing $282,000 from the plant's decommissioning trust fund before they were authorized to do so. But in that case, the NRC noted that a lack of clarity in federal regulations likely contributed to the problem.