“Medusa” is freed at Hanford
Workers at the Department of Energy’s Hanford Site in Washington state recently removed a complex piece of equipment that had been standing in the way of future tank waste retrieval.
Dubbed “Medusa” after the Greek mythological creature with snakes for hair, the multihose connector was used for nearly 25 years to move radioactive liquid waste between storage tanks before it went inactive in 1980.
Prep work: In late 2021, crews with the DOE’s tank operations contractor Washington River Protection Solutions (WRPS) put a camera in one of the concrete pits at the A Tank Farm to prepare to retrieve waste. That’s when they discovered Medusa and started working on plans to remove it.
“Removing equipment connected to the underground tanks to provide access to retrieve single-shell tanks is important work, given the waste stored inside,” said Jim Greene, manager of the Tank Farms Program Division’s Single-Shell Tank Retrievals Program. “This removal work is an example of a cross-organizational collaboration to reduce radiological dose rates for the team and advance Hanford’s cleanup mission to protect the community and the environment.”
Workers used long-reach tools to clean out an enclosure above Tank A-102 so that pipefitters could remove Medusa’s welding and break the equipment free. (Photo: DOE)
It took two days for two pipefitters, who worked inside the Tank A-102 enclosure on the Hanford Site, to break some welded equipment free. (Photo: DOE)
Freeing Medusa: In early 2022, workers used long-reach tools to remove and dispose of the hoses, clear out miscellaneous debris, and encapsulate contamination in the concrete Medusa pit at Tank A-102. The connector itself, however, was welded in place and could not be removed with a long-reach tool.
The pit is only 6 feet by 6 feet wide and just under 9 feet deep. It took crews months of planning to access Medusa because long removal tools could not reach it. This past June, it took two pipefitters individually working inside the tight enclosure two days of grinding a weld to break Medusa free.
“Working together as a team is essential for success on all jobs out here, especially when safety issues arise,” said Marco Nicacio, a pipefitter with subcontractor AEI Construction, who wore a double set of protective clothing along with fire retardant wear and a welder’s jacket and arm sleeves to do the work. “It’s a small, crowded pit, and we had to ensure the welding sparks and grinding dust were contained as best as possible. I felt comfortable, confident, and safe while performing my tasks of the job.”
Crews used a crane to pull the connector from the pit, reducing the radiological exposure to workers by 90 percent from the original estimate.
“This was challenging, but it is a success story,” said Kalli Walton, the WRPS waste retrievals project manager overseeing the A Tank Farm operations. “We took our time and made sure we had the correct controls in place and everybody’s input was incorporated. At the end of the day, we got our pit cleared.”
Notes: The radioactive and chemical waste storage tanks are in letter-designated underground fields, called tank farms, at Hanford. Tank A-102 holds about 41,000 gallons of waste. Waste retrieval activities are scheduled for the summer of 2025.