Contingency plan for the Old Hydrofracture Facility Tanks Sluicing Project at Oak Ridge National Laboratory, Oak Ridge, Tennessee

This revised contingency plan addresses potential scenarios involving the release of radioactively contaminated waste from the Old Hydrofracture Facility Tanks Contents Removal project to the environment. The tanks are located at the Oak Ridge National Laboratory. The project involves sluicing the contents of the five underground tanks to mix the sludge and supernatant layers, and pumping the mixture to the Melton Valley Storage Tanks (MVST) for future processing. The sluicing system to be used for the project consists of a spray nozzle designated the {open_quotes}Borehole Miner,{close_quotes} with an associated pump; in-tank submersible pumps to transfer tank contents from the sluice tanks to the recycle tank; high-pressure pumps providing slurry circulation and slurry transport to the MVST; piping; a ventilation system; a process water system; an instrumentation and control system centered around a programmable logic controller; a video monitoring system; and auxiliary equipment. The earlier version of this plan, which was developed during the preliminary design phase of the project, identified eight scenarios in which waste from the tanks might be released to the environment as a result of unanticipated equipment failure or an accident (e.g., vehicular accident). One of those scenarios, nuclear criticality, is no longer addressed by this plan because the tank waste will be isotopically diluted before sluicing begins. The other seven scenarios have been combined into three, and a fourth, Borehole Miner Failure, has been added as follows: (1) underground release from the tanks; (2) aboveground release or spill from the sluicing system, a tank riser, or the transfer pipeline; (3) release of unfiltered air through the ventilation system; and (4) Borehole Miner arm retraction failure. Methods for preventing, detecting, and responding to each release scenario are set out in the plan