VERNON — A Vermont Yankee employee's deliberate failure to check radiation exposure monitors was a “personal accountability issue,” and no other staffers engaged in such behavior, the company says.
In a new filing with the Nuclear Regulatory Commission, Entergy says it conducted an extensive review after federal inspectors discovered that a staffer hadn't checked the functionality of personnel contamination monitors for eight months in 2016.
The technician in question was fired, Entergy says. The company found no evidence of similar problems after a review that included radiation protection operations at Vermont Yankee and other Entergy sites.
The company also said its research “provides reasonable assurance that the [monitors] continued to function adequately to detect potential contamination” in spite of the employee's actions.
Though Vermont Yankee stopped power production at the end of 2014, employees still must be monitored for radiation exposure. The largest source of radioactivity is the Vernon plant's spent fuel, and most of that material remains in a cooling pool in the reactor building.
Mandated daily checks
Personnel contamination monitors are used to “prevent the inadvertent release of radioactive material” as staffers leave the plant's radiologically controlled area, Entergy says. And the company has mandated daily checks of those monitors to ensure they're working properly.
But the NRC in June disclosed that, between Jan. 19 and Sept. 20 of last year, a senior radiation protection technician “deliberately did not perform those checks.” The unidentified technician denied that, but federal inspectors found evidence to the contrary on the contamination monitors' hard drives.
The incident resulted in the NRC issuing a “severity level IV” violation, which is the least-severe classification.
However, “Entergy was required to provide a response detailing its corrective actions because the violation was willful and was not identified by the company,” NRC spokesman Neil Sheehan said.
The company's response, dated July 25, indicates that Entergy learned of the issue in early November when an NRC investigator requested information from the contamination monitors.
The downloaded data “revealed an apparent pattern of daily response checks not being recorded during certain shifts,” and those shifts had been assigned to one technician.
Though the employee had initialed forms and made log entries indicating that the checks had been completed, Entergy found that there was a “willful decision not to satisfy the assigned responsibility.” The staffer understood that responsibility, and acted “without direction or authorization from supervision,” the company says.
On Nov. 8, Entergy revoked the technician's site access. The employee was terminated in December, documents say.
The company noted that the monitors have a computer that will automatically deactivate the device if there is a problem. That didn't happen with the monitors in question, and Entergy also reviewed data showing that the monitors worked correctly the day before and the day after they had been neglected by the technician.
The NRC shares that viewpoint, with Sheehan saying there is “no evidence the detectors failed to properly operate.”
Repeated reviews
Entergy says it also undertook several reviews to find any evidence of similar radiation monitor problems.
One review included a wide variety of documentation and found “no significant discrepancies” in the work of other technicians at the plant.
That same review, however, found that the terminated technician also had apparently failed to complete a chemistry lab drain survey on two dates - Sept. 27 and Oct. 30 - even though documentation indicated that the work had been done.
That wasn't mentioned in the NRC's original safety violation. Asked about the chemistry lab report, Sheehan said only that the NRC “will carefully review the company's response and determine if any further actions are warranted.”
Entergy also conducted two other evaluations related to the radiation monitor issue.
One included periodic review of the monitors' data from Jan. 1 to June 25 of this year. The company found “no instances” of monitor checks not being performed.
Additionally, other Entergy sites were checked for radiation monitor problems. Aside from “minor discrepancies,” the company said, “no integrity issues were identified.”
Entergy says its actions show that “full compliance was achieved.” But the NRC will double-check that.
“We will be following up on the company's corrective actions during a future inspection,” Sheehan said.