The Department of Energy plans to grout the second PUREX Plant waste tunnel at the Hanford Site in Washington state, just as it did the first tunnel after it was discovered partially collapsed May 9.
The Washington state Department of Ecology had ordered DOE to by Dec. 8 propose a stabilization plan for the second and larger tunnel filled with radioactively contaminated equipment from the former plutonium extraction plant.
DOE met with the Department of Ecology on Tuesday afternoon and announced shortly afterward that it planned to fill the second tunnel with grout under its contingency plan.
The Ecology Department had just begun to review what it considered a proposal Tuesday and said DOE’s plan would require modification of its state permit. The assessment will include comment periods and at least one public meeting on the proposal, said Alex Smith, manager of Ecology’s Nuclear Waste Program.
The Energy Department convened a panel of experts to consider options for the second, 1,700-foot-long tunnel, which holds 28 railcars loaded with failed equipment that is highly contaminated with radioactive waste. A structural review prompted by the partial collapse of the first, 360-foot-long tunnel found that the second tunnel also was at risk of collapse.
“In the panel’s opinion, the grout stabilization provides maximum protection to workers, the public, and the environment,” said the expert report. “Furthermore, the panel concluded that stabilization with grout facilitates future options for disposition, whether those options involve in-situ disposal or removal of materials.”
The panel considered factors such as worker safety, environmental protection, schedule, costs, and whether future options for cleanup of the tunnel would remain open. Options included covering the tunnel with heavy plastic, a tent, or a pre-engineered building; injecting a poly foam; filling it with sand or clay; conducting a controlled collapse; retrieving the waste; or filling the tunnel with grout.
