RICHLAND - Washington River Protection Solutions (WRPS) has advised the U.S. Department of Energy (DOE) that they have completed retrieval of radioactive and chemical waste from the third single-shell tank (SST) this year. WRPS is the tank operations contractor for the DOE Office of River Protection (ORP).
An engineering evaluation in the field shows the waste volume in C-109 is below the regulatory requirement of 360 cubic feet of waste remaining in the tank. Video of the 530,000-gallon-capacity tank shows a large percentage of the tank bottom is now visible.
“The completion of retrieval activities in the second tank within a month and the third tank this year marks a historic achievement at Hanford tank farms,” said Tom Fletcher, Assistant Manager for the Tank Farms Project. “Crews are working at an impressive pace to complete retrieval activities in the next tank by the end of October and begin removing waste from the next round of tanks by the end of this year.”
Retrieval of C-109 began in June 2007 using modified sluicing as the first retrieval technology. This process used recycled liquid waste from a nearby double-shell tank to mobilize the waste to the center of the tank where it was pumped and transferred to a receiving tank. This process continued until July 2008 at which point the bulk of the waste was removed, leaving an estimated 8,600 gallons of hard-heel waste to be retrieved.
Deployment of a second retrieval technology in C-109 took place earlier this year, as crews began a two-step chemical soak process to dissolve the hardened remaining waste, first by performing a water soak and then adding sodium hydroxide to the tank to loosen and break down the hardened waste at the bottom of the tank. This chemical dissolution process has been used successfully in two other Hanford tanks this year, C-104 and C-108.
“As we continue to perform these activities we learn more about the chemical dissolution process,” said Joanne Grindstaff, Federal Project Director for SST Retrieval and Closure. “A number of efficiencies are being gained through the ongoing deployment of this second technology, as the hard-heel waste becomes readily mobilized—an important step in maximizing the amount of waste that can be retrieved.”
This past week, C-109 underwent a series of water rinses to further reduce the amount of residual waste in the tank.
In addition to C-109, crews this year also completed retrieval efforts in tanks C-108 and C-104. Waste has been removed from a total of 10 SSTs at the Hanford site, nine tanks in C Farm and one tank in S Farm. ORP and WRPS are committed to meeting the Consent Decree regulatory requirement to retrieve waste from all the tanks in C Farm by September 2014.
WRPS is the DOE ORP prime contractor responsible for managing the risk to the environment posed by Hanford’s 56 million gallons of high-level radioactive and chemical waste stored in 177 underground tanks. ORP is responsible for safely retrieving and treating Hanford’s tank waste, resulting from defense nuclear material production, and closing the tank farms to protect the Columbia River. WRPS is owned by URS Corporation and Energy Solutions, with AREVA as its primary subcontractor.