Two scientists from Woods Hole Oceanographic Institution spoke Monday about the fate of radioactive water in Cape Cod Bay if the Pilgrim Nuclear Power Station were to release the water as proposed.
The question of whether radioactivity in the water would pose a threat to human health and the environment has sparked protests and heated debate at meetings of the state’s Nuclear Decommissioning Citizens Advisory Panel.
The panel invited the scientists to speak.
Marine radiochemist Ken Buesseler said the accumulation of radioactive elements would be different depending on the element and the location, such as in seawater, seafloor sediments, and sea life.
“If you were to release things that have multiple forms of radioactivity, you would probably want to assess those — before, during and after any release,” he said. “Because they behave differently.”
He said the water at Pilgrim should be treated to reduce the concentration of radioactive elements, especially the more harmful ones, such as Cesium-137. Tritium could not be removed, but it decays faster than some of the others.
“If you just cleaned up the things that were more harmful on my list, you would be left with water that’s largely tritium,” he said. “And you could hold that for its decay — 12-year half-life.”
If the treated water were stored, more than 95 percent of the tritium would be gone in 60 years.
David Noyes, a compliance manager with Pilgrim owner Holtec International, said treatment would reduce radioactivity in the water to make it comparable to water the plant released in 2015, when it was operating.
Radioactivity levels “will change, through treatment, to numbers that were representative of the 2015 releases, because that is the treatment system,” he said. “That’s the capability of the treatment system — to reduce the concentration of that isotope by that factor.”
Holtec is seeking to discharge nearly 1 million gallons of wastewater from the reactor system as part of the plant decommissioning. The reactor was shut down in 2019.
The volume was originally more than 1 million gallons, but it has been evaporating, partly through natural evaporation and partly accelerated by submerged heaters that operate in the plant during cold weather.
As of Nov. 15, the volume of water had fallen to 916,442 gallons, Noyes said.
Buesseler said he sees a difference between releasing radioactive water while a nuclear plant is generating renewable energy and doing so after it shuts down.
“To me, that sets a precedent,” he said. “We don’t want to use, in my opinion, the ocean for putting in radioactive waste materials. Yet I truly realize that nuclear power plants around the world do this all the time for the benefit of providing carbon free electricity.”
Another WHOI scientist, physical oceanographer Irina Rypina, joined the panel meeting by video to present data on how ocean currents could transport pollution in Cape Cod Bay.
She said the probability of pollution traveling near the shoreline, including off Dennis, Wellfleet, and Provincetown, is high, especially in winter and fall, due to prevailing winds. The probability of pollution leaving the bay without going near the shoreline is low in spring and summer, but virtually zero in winter and fall, she said.
Also during the meeting, Seth Pickering, a deputy regional director at the state Department of Environmental Protection, said Holtec wants to evaporate 4,000 gallons of sodium pentaborate solution into the outdoor air.
This action would be separate from the evaporation of radioactive water.
Pilgrim kept the solution as a backup way to shut down the reactor in an emergency, Noyes said.
Pickering said the department has asked Holtec not to conduct a 55-gallon test of the evaporation until the state reviews the issue.
“The department’s in the process of preparing questions regarding Holtec’s evaporation proposal in regard to air quality and waste treatment and/or disposal,” he said. The agency is evaluating where state regulations may apply.
Sodium pentaborate is a compound of sodium, boron, and oxygen. It can shut down a reactor by absorbing neutrons.
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