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242-A Evaporator

The 242-A Evaporator Facility is a vital facility for tank
space management, supporting both DFLAW and tank retrieval.


The U.S. Department of Energy and contractor Washington River Protection Solutions LLC are safely and compliantly operating and upgrading the 242-A Evaporator Facility supporting tank waste volume management at the Hanford Site in southeastern Washington State.


The 242-A Evaporator Facility is centrally located in the Hanford Site’s 200 East Area. 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 water to reduce the volume of waste stored in Hanford’s underground tanks. Waste volume reduction is also critical for single-shell tank (SST) waste retrievals to double-shell tanks (DST). In order to meet Consent Decree milestones, DST space availability is a key factor in continuing SST retrievals. The 242-A Evaporator is currently shut down for facility upgrades to prepare for future waste volume reduction campaigns.


Support retrieval operations of SSTs and achieve waste volume reduction to maximize DST space availability through the evaporation of water from liquid tank waste.


The 242-A evaporator is a Hazard Category 2 nuclear facility. In operations mode the facility concentrates radioactive and hazardous waste. Exposure to radiation, hazardous materials, and standard industrial hazards is the primary risks to facility workers from normal operations. The 43-year-old facility must be maintained to support the waste volume reduction operations.

Safety and Efficiency

Hanford has a long history operating the waste reduction campaigns safely and efficiently at the 242-A Evaporator Facility. Facility and operational hazards are mitigated though safety management programs like safety and health and waste management programs. The labor force is highly trained in the functions and safeguards that are in place to ensure safe and compliant operations.


Since FY 2014 the 242-A Evaporator has created nearly three million gallons of high-level waste storage space (waste volume reduction) – the equivalent of nearly three DSTs.

Currently not in the Waste Volume Reduction operating mode (resuming in FY 2022).

Transfer line replacement and facility modifications are currently in the design and procurement stages (completion in FY 2022).


With the completion of the transfer line replacement project and various facility upgrades (FY 2022 completion), the evaporator will continue to play a critical role in waste volume management for the Hanford Site for decades to come. Restart of the 242-A Evaporator will provide DST space for AX-101 retrieval in FY 2022.



  • The 242-A Evaporator has operated since 1977, reducing the volume of waste stored in DSTs and making room for waste retrieved from SSTs. Liquid waste is pumped to the 242-A Evaporator from nearby DST AW-102 through the underground double-walled transfer lines.


  • Waste is heated in a sealed vessel under partial vacuum to boil the waste at 125 degrees Fahrenheit, nearly 90 degrees lower than at normal atmospheric pressure. Water evaporated from the waste is captured, filtered, and sent to the nearby Effluent Treatment Facility for disposal.


  • The 242-A Evaporator has removed more than 80 million gallons of water from Hanford’s tank waste, maximizing DST storage space.











The 242-A Evaporator Facility is monitored closely by the operations staff in the Evaporator Control Room.


242-A Evaporator at Night.
242-A Evaporator at Night.


Replacement slurry and feed transfer lines for the 242-A Evaporator.
Replacement slurry and feed transfer lines for the 242-A Evaporator.


Evaporator 5
Evaporator 5

Last Updated 03/29/2022 2:29 PM