The US Department of Energy’s (DOE’s) Office of Environmental Management (EM) has awarded the Hanford Integrated Tank Disposition Contract (ITDC) to Hanford Tank Waste Operations & Closure (H2C) of Lynchburg, Virginia, for work to be performed at the Hanford Site in southeastern Washington state. H2C is a newly formed limited liability company comprising BWXT Technical Services Group, Amentum Environment & Energy, and Fluor Federal Services.

The Indefinite Delivery Indefinite Quantity contract will have a maximum value of $45 billion over a 10-year ordering period. The contract includes requirements for meaningful work to be performed by small businesses and will promote community engagement, including support to site reindustrialisation by the local community. Submission of a community commitment plan to DOE is required. Work to be performed under the new Hanford ITDC will include, but not be limited to the following:

  • Operation of tank farm facilities, including single-shell tank waste retrieval and closure;
  • Design, construction, and operation of waste receiving facilities and treatment capabilities;
  • Operation of the Waste Treatment and Immobilisation Plant; and
  • Core functions such as project management; environment, safety, health, and quality; security and emergency services; and business performance requirements.

For more than 30 years, EM has remained focused on addressing the environmental legacy of nuclear weapons development and nuclear energy research during World War II and Cold War.

Hanford is home to 177 underground waste storage tanks: 149 single-shell tanks (SST), and 28 double-shell tanks (DST), ranging from 55,000 to 1.265m gallons in capacity. Those tanks are organised into 18 different groups called farms. Currently, the site's underground tanks store approximately 56m gallons of radioactive and chemical waste. The overall mission of single-shell tank farm retrieval consists of safely retrieving tank waste from ageing SSTs and transferring waste into newer, more robust double-shell tanks until it can be treated, immobilised and placed in long-term storage.

Construction of DSTs began in 1968. Each DST has a carbon-steel inner tank with a separate steel liner surrounding it to prevent leaks to the environment. The tank liners are separated by an air space of about 30 inches, equipped with a leak-detection system. As part of the Hanford Tank Integrity Program, a team of engineers, supported by a group of independent experts, regularly reviews pertinent information regarding construction and operation of Hanford’s waste-storage tanks. These experts monitor the integrity of the tanks by examining waste chemistries, corrosion rates, storage histories and changing conditions. Periodic tank inspections are performed with ultrasonic testing, visual inspection and waste sampling.

A critical part of managing the waste relates to the amount of available storage space in the tanks. Hanford’s 242-A Evaporator is critical to managing tank space. The evaporator takes in waste from the DST system and boils it. The water vapour from the boiling waste is collected, condensed, filtered, and sent to another Hanford facility for treatment, resulting in a reduced volume of tank waste. The remaining concentrated waste is transferred back to a DST. The 242-A Evaporator is the workhorse that frees up space in the DSTs and allows for waste to be transferred from the older SSTs to the newer DSTs.

Preparations to retrieve radioactive and chemical waste from another group of large underground tanks at the Hanford Site are gaining momentum. DOE recently drilled an opening through the thick concrete top of Tank A-106 to provide access for waste retrieval equipment.

Within the next year, workers will begin retrieving waste from six older single-shell tanks in the A Tank Farm, one of 18 farms at Hanford that received waste generated during plutonium production. Crews will transfer the waste to a newer double-shell tank for safe storage until it is treated.

Workers also recently installed a pump in Tank A-101, the first tank in A Farm scheduled for retrieval. Soon workers will install two more large pieces of equipment in the tank to break down waste during retrieval operations. Waste retrieval in A Farm is scheduled to start in the summer of 2024. The A Farm tanks were built in the mid-1950s, and store waste generated by plutonium processing at the nearby Plutonium Uranium Extraction Plant during the Cold War era.

Hanford’s C Farm, with 16 underground tanks, was the first tank farm to be completely retrieved, five years ago. Retrieval of one tank in the S Farm was completed in 2007. Workers are retrieving waste from the last of the four tanks in the AX Farm.

As part of an agreement regulating Hanford cleanup, crews must remove at least 99% of the waste in every tank on the Site, or at least as much waste as can be removed based on available technology. The final for the tank farm waste is treatment at the Waste Treatment & Immobilisation Plant.

Image courtesy of US Department of Energy