Idaho Treatment Facility Resumes Heat-Up Following Maintenance

IDAHO FALLS, Idaho – Heat-up of a liquid waste treatment facility has resumed this month in anticipation of beginning radiological operations at the facility at DOE’s Idaho National Laboratory Site.

Most recently, EM crews at the Integrated Waste Treatment Unit (IWTU) removed a partial obstruction within a line into the Carbon Reduction Reformer, a key treatment vessel in the steam-reforming process. The temperature of the facility was reduced to allow for safe maintenance of the line.

Earlier, crews completed repairs to equipment responsible for a leak of nonradiological material inside one of the facility’s processing cells.

To perform the repairs, welders installed a thick, stainless steel plate over a hole that formed in a valve body inside one of the facility’s two cells where dried, treated material will be transferred to long, stainless steel canisters. The filled canisters will then be placed into concrete vaults for long term storage. A similar valve in the second cell was also modified in the same way as a precaution.

Shortly before the completion of the heat-up process in late December, IWTU operators noticed the nonradiological solids leak during routine inspection of the shielded cell using installed cameras. The leak occurred during a normal purging process, which directs bursts of nitrogen through stainless steel lines to prepare for the transfer of treated simulant. Operators immediately began a normal shutdown of IWTU.

Following the shutdown and cooldown of the facility, investigation of the leak revealed the damaged valve body. Inspections indicated the damage was erosion of the valve body due to the interaction of alumina and nitrogen purges. Alumina, a commonly used material in sandpaper, is introduced into the IWTU’s steam-reforming process to improve the movement, or fluidization, of dried waste material inside the facility’s primary reaction vessel. Inspections extended to other parts of the facility that have similar valves, but no other wear was noted.

Approximately 900,000 gallons of sodium-bearing liquid waste from three nearby underground stainless steel storage tanks will be converted to a more stable granular solid. The tanks will then be cleaned and grouted, and the group of tanks will be closed under federal and state regulations. Treated waste will be stored onsite until a national geologic repository is available for permanent disposal of IWTU’s treated waste.

Moving forward, the canister-fill cell lines will be purged for a shorter duration to reduce the likelihood of wear to the valves.

The leak of nonradiological material also allowed engineers to consider how they would respond in case of a similar event during radiological operations. Radiation exposure would be primarily managed by shielding and increasing the distance between the worker and source of radiation. Contamination levels would be controlled though use of containment tents, ventilation and cleanup.