Submerged heaters have been installed inside the reactor at the Pilgrim Nuclear Power Station and likely increased the release of radioactive tritium into the air, according to a federal inspection report.
The report this month by the Nuclear Regulatory Commission says the heaters will cause more evaporation and probably a slight increase in tritium passing through the ventilation system in the reactor building.
The information came to light when local activist group Cape Downwinders said it received an anonymous letter, which the group released Tuesday.
The letter claims that radiation protection staff inside the plant raised safety concerns about the change. The claim could not be immediately verified, nor could the source of the letter be determined.
Pilgrim owner Holtec International has been trying to get approval to dispose of water from the closed plant, either through direct release into Cape Cod Bay, evaporation, or some other method.
The state Department of Environmental Protection issued a tentative denial last month of a permit for Holtec to release more than a million gallons of wastewater into Cape Cod Bay.
Now, Cape Downwinders Director Diane Turco says the company could be turning its attention to evaporation instead.
“To us, it looks like, well, Holtec can't dump in the water now, so they're going to start discharging into our air,” she said.
But Holtec spokesman Patrick O’Brien said evaporation is not the reason for the new heaters.
He said the heaters were installed around December of last year and serve two purposes: to warm the water enough to use submerged equipment in the winter as part of the plant decommissioning, and to make the plant warmer for employees’ comfort.
“There’s conditions needed to operate equipment underwater,” he said. “Those conditions needed to be met. So you put in heaters to ensure that you stay within the limits required to use the equipment.”
The heaters are not operating during the summer.
Turco said she’s concerned evaporation could lead to more human exposure to tritium.
“The way it's heated, does that change the concentration in the water?” she said. “And we also know that evaporation presents a more direct ingestion pathway for people to be externally exposed.”
O’Brien said workers wear real-time monitors whenever they enter the radiologically controlled area of the plant, and the monitors have alarms to alert workers to leave if radiation becomes elevated.
The anonymous letter, addressed to Cape Downwinders and the Massachusetts Department of Public Health, claims that public radiation exposure from tritium in the vapor would be “many times greater” than public exposure from water released into Cape Cod Bay.
O’Brien agreed with that assessment.
“That is something we have said publicly numerous times in our discussions, that evaporative [release] is more impactful,” he said. “But it is still well below federal limits.”
Turco said the pollution is unacceptable, whether it goes into the air or into Cape Cod Bay.
She said the federal inspection is not enough, and she called for an independent investigation.
The inspection concluded that Pilgrim had “no violations of more than minor safety significance."
The state plans to hold a hearing on Holtec’s water discharge permit tomorrow at 6 p.m. at Plymouth Town Hall.
