U.S. Department of Energy officials are continuing to evaluate the possibility of entombing the Molten Salt Reactor Experiment at the Oak Ridge National Laboratory (ORNL) in Tennessee, possibly burying contaminated structures below ground in grout.
The DOE Oak Ridge Office of Environmental Management is starting a planning process that could be part of a phased feasibility study on entombment, which the department refers to as in-situ decommissioning, according to Bill McMillan, ORNL portfolio federal project director for the office.
Among other steps, the planning process could evaluate the hazards and structures at the Molten Salt Reactor Experiment and identify what data is needed for the study, McMillan told the Oak Ridge Site Specific Advisory Board on Wednesday. Fuel drain tanks that are radioactive and below ground may need to be sampled, and DOE might have to consider what pipes must be removed from the building, he said.
The feasibility study will then investigate how much of the MSRE should be entombed, if that is the approved approach; model potential long-term releases from the site; evaluate the use of a material to capture fluorine generated in the drain tanks; and evaluate the grout materials that could be used, McMillan said. He said monitoring systems will be required for long-term stewardship.
The feasibility study, which could take three years, could lead to a revised record of decision that would formalize the department’s plan for disposition of the reactor, McMillan said: “We believe it is something to continue looking at.”
Entombment would bury underground structures that include the fuel drain tanks that are contaminated with radioactive fission products, including cesium-137 and strontium-90. The Energy Department has previously said parts of the Molten Salt Reactor Experiment are too radioactively “hot” for humans.
Most of the fuel at the Molten Salt Reactor Experiment, which operated from June 1965 to December 1969, has been removed.
