At the Hanford Site, waste retrieval has been completed in 17 of 149 large concrete underground single-shell tanks (SSTs).
Office of Environmental Management
March 5, 2019
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RICHLAND, Wash. – At the Hanford Site, waste retrieval has been completed in 17 of 149 large concrete underground single-shell tanks (SSTs). The tanks were constructed of carbon steel and reinforced concrete between 1943 and 1964 to store a radioactive mix of sludge and saltcake waste from nuclear processing activities.
Management and disposition of this waste is the responsibility of EM's Office of River Protection, assisted by Washington River Protection Solutions (WRPS), operations contractor for the Hanford tank farms.
Because of the potential to reduce the overall time and cost required to retrieve the waste and prepare the tanks for closure, WRPS is considering options for installing new access holes in the tank domes for future retrieval efforts.
Working with Becht Engineering, Pacific Northwest National Laboratory (PNNL) completed a structural analysis of an SST dome with new access holes for deploying waste retrieval equipment.
Their analysis confirms the continued structural integrity of the SSTs with new dome penetrations and retrieval equipment loads on the soil above the tank dome. The analysis concluded:
- It may be less expensive to bore new penetrations and install new risers in the tank domes than to remove existing contaminated hardware in existing risers.
- New large access holes up to 6 feet in diameter.
Kenneth Johnson, a mechanical engineer in PNNL’s experimental and computational engineering group, presented the analysis at this year’s Waste Management Symposia in Phoenix.
"Removing long-length equipment from Hanford’s SSTs is one of the most difficult and time-consuming activities associated with tank waste retrieval,” said Keith Carpenter, WRPS engineer. “The analytical work completed by PNNL is another great step forward in our pursuit of installing new risers in the SSTs and minimizing the amount of long-length equipment that must be removed.”
The study team included Ken Johnson, Naveen Karri, and John Deibler of PNNL; and F. George Abatt, Ken Stoops, Larry Julyk, and Brian Larsen of Becht Engineering.
