A recent inspection at a shuttered Massachusetts nuclear power plant revealed that multiple contract workers at the site were inadvertently exposed to radiation during decommissioning work, the Nuclear Regulatory Commission said in a letter to the company in charge of the facility.
Holtec International, which is currently decommissioning Pilgrim Nuclear Power Station, failed to “perform radiological air samples to assess the potential airborne radioactivity” during 2020 work in the drywell section of the reactor housing its control rod drive systems, NRC told the company in a November letter made public Wednesday.
Because Holtec didn’t perform the required radiation surveys, six contract workers at the Plymouth, Mass., facility “received unplanned intakes of radioactive material” while working on the drive systems, NRC said.
A spokesperson for the agency told RadWaste Monitor via email Wednesday that the contractors were exposed to “a mixture of several radionuclides commonly seen in power reactors,” mainly cobalt-60, which decays in penetrating gamma rays.
All doses were less than 10 millirems, or around the dose a plant worker might receive from internal contamination after working at a nuclear power plant for 50-years, the spokesperson said. It was “assumed” for the purposes of dose estimates that the contaminated workers received radioactive uptake, the spokesperson said, meaning contamination was inhaled or otherwise got inside their bodies.
According to the NRC report, the contractors were found to be contaminated with radioactivity on two different occasions in August after working in the drywell dismantling the control rod drives. After the initial incident, where two workers were dosed, the plant’s radiation protection division modified the process for removing contamination suits to reduce exposure to potentially contaminated airflow, the agency said.
“This proved to be ineffective,” the report said, since four more workers were exposed to radioactivity just a few days later. The dose estimates for these exposures “were determined to be very low,” NRC said.
The commission’s inspection revealed that the carts used to transfer drive system parts had very high levels of surface contamination, and that the decontamination process for the workers’ suits “was not comprehensive.” Those deficiencies contributed to the six exposures, NRC said.
Despite that, NRC told Holtec that it would consider the violation a “non-cited” offense, meaning that the agency won’t take further enforcement action. The agency came to that conclusion because the company took corrective action on the violation and because “the violation was not willful or repetitive,” the report said.
“This type of work is not new, nor unique, to Pilgrim and is also performed within operating Boiling Water Reactors,” a spokesperson for Holtec told RadWaste Monitor via email Thursday morning. “As identified in the NRC report some individuals were exposed to additional contamination well below Federal limits. We entered the issue into our corrective action program to ensure it is properly resolved and the learnings can be implemented for any similar work in the future.”
Holtec in 2018 purchased the Pilgrim plant from former operator Entergy. The company has said that it could finish dismantling the facility by 2027 or so.
