Improvements to Hanford’s 242-A Evaporator Facility continue to be made as the Department of Energy prepares to begin its direct-feed low-activity waste (DFLAW) approach to treating radioactive liquid waste at the site near Richland, Wash. The DOE announced on November 3 that its Office of River Protection and contractor Washington River Protection Solutions (WRPS) have completed several major upgrades and repairs at the evaporator, and more are planned.
Used to reduce waste volume by removing liquid from Hanford’s underground storage tanks, the 242-A Evaporator is fundamental to the Hanford Site tank waste mission and will play an essential part in the DFLAW treatment approach, according to the DOE.
Background: Since its construction in 1977, the evaporator has removed more than 81 million gallons of liquid from Hanford’s tank waste. The 242-A Evaporator boils liquid tank waste to evaporate and remove water and most volatile organics. According to the DOE, the evaporator has reduced the volume of waste stored in Hanford’s underground tanks by as much as 40 percent.
Vapor from the boiling waste is condensed, filtered, and sent to Hanford’s Effluent Treatment Facility for disposal. The remaining slurry is sent back to a double-shell waste tank.
Improvements: Recent improvements to the 242-A Evaporator include a new instrument air dryer and a new air receiver tank and piping. Workers also upgraded the facility’s monitoring and control system, updating system hardware and software, and improving cybersecurity, the DOE said.
Designs for replacing three waste transfer lines were recently completed by WRPS. Double-walled piping is used to move tank waste from double-shell tanks to the evaporator for reduction and to send the resulting slurry back to a tank.
After 40 years of service, the original slurry lines were taken out of service in 2018 after they failed periodic pressure testing of the outer encasement piping. While the inner piping that transfers waste has not leaked, the DOE said that the encasement line integrity could not be verified. The DOE’s Office of Environmental Management decided to install three new lines, one to transfer tank waste to the evaporator, one to return slurry back to the tank, and a backup line.
Other improvements will include a safety system upgrade that will increase the efficiency of equipment testing required prior to an evaporator campaign. All improvements to the 242-A Evaporator, including the installation of the new waste transfer lines, are expected to be completed in fiscal year 2022, according to the Hanford website. The DOE aims to begin treating waste using DFLAW by the end of 2023.