The US Department of Energy (DOE) Office of Environmental Management (EM) and contractor Washington River Protection Solutions (WRPS) have developed a new approach to refurbish double-shell tanks (DSTs) at the Hanford Site, Washington, USA.
DSTs were constructed between 1968 and 1986 to hold waste transferred from aging single-shell tanks. These are large, underground tanks that consist of a primary carbon-steel tank inside a secondary carbon-steel liner, surrounded by a reinforced concrete shell. The tanks store waste created during Hanford’s plutonium production era. They support feeding the treated waste to Hanford’s low-activity waste vitrification facility at the Waste Treatment and Immobilization Plant. Vitrification is a process in which the waste is immobilised in glass.
Crews use a technology known as ‘cold spray’ that applies metal patches by shooting metal powder on a surface at supersonic speed, causing it to adhere to the surface without melting either material. While other industries use this technology, it had not been extensively evaluated for use at the Hanford Tank Farms.
Stephanie Doll, WRPS technical lead for tank refurbishment projects says: ‘I’m impressed with cold spray technology and its potential application for the Hanford double-shell tanks, based on data we’ve gathered during full-scale demonstrations. The field crew involved in deploying and operating the equipment is equally as impressive. Their invaluable feedback and proficiency have been key to our success so far.’
