Part of the contaminated site of Oak Ridge’s old Molten Salt Reactor Experiment may be entombed in concrete, according to Jay Mullis, manager for the Oak Ridge Office of Environmental Management.
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Part of the contaminated site of Oak Ridge’s old Molten Salt Reactor Experiment may be entombed in concrete, according to Jay Mullis, manager for the Oak Ridge Office of Environmental Management.
Mullis told the board the fuel was interstitial to the salts, which means the contaminants are disseminated between the grains. Environmental Management began chemically removing the fuel about 10 years ago by using probes to heat up sections of the salt, since the heaters around the salt had not been operated since the 1960s.
“There are trace amounts of those fuels left,” Mullis said. “There’s also fission products in there, principally cesium and strontium.”
Underground and covered by shield plugs, the radioactive tanks run between 500 and 1,000 Roentgens, a legacy unit for measuring radioactivity.
That’s about 100 to 200 times the amount radiation workers are allowed to be exposed to in an entire calendar year.
Because the radioactive contaminants are in the salt, removing it risks dispersing it.
“It’s a very hazardous operation for us,” Mullis said. It’s also an expensive one.
Ben Williams, Oak Ridge Environmental Management spokesman, said the office estimates removing the material and shipping it off to the Waste Isolation Pilot Plant in New Mexico could cost between $150 million and $200 million.
The office has to spend money anyway maintaining the special nuclear material.
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Entombment is the cheaper route and has been done before — most notably, at Chernobyl, where the contents of the steel and concrete sarcophagus are expected to remain radioactive for at least the next 10,000 years.
A second seal was placed over the hot zone just last year.
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In the United States, entombment had been used in Ohio and Nebraska to contain radioactive pieces of other nuclear power plants decommissioned in the late 1960s, and to cocoon nine plutonium reactors at the Hanford Site in Washington state.
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