July 15, 2024 [Energy Gov]- The U.S. Department of Energy (DOE) Office of Environmental Management (EM) and contractor Washington River Protection Solutions (WRPS) recently demonstrated a potential new approach to refurbish double-shell tanks (DSTs) at the Hanford Site.

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 immobilized in glass.

Crews used 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.

“DOE is exploring potential refurbishment technologies that will extend the lifespan of Hanford’s large underground tanks in support of the tank waste mission, including the Direct-Feed Low-Activity Waste Program,” said Erik Nelson, EM technical lead for tank and pipeline integrity at Hanford.

WRPS, along with its partners, has spent three years developing a method to combine cold spray and robot technology to refurbish areas of DSTs.

Previously, crews used mock-up demonstrations at Hanford’s Cold Test Facility to show that robotic equipment can be lowered into the space between the first and second shell of a DST, known as the annulus, to navigate the space. Crews recently demonstrated that robots equipped with the cold spray technology can also refurbish a mock annulus floor.

“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,” said Stephanie Doll, WRPS technical lead for tank refurbishment projects. “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.”

The recent demonstration validated the system’s capabilities, and the team’s progress brings the technology a step closer to potentially joining Hanford’s’ tank integrity toolkit.