January 04, 2016

Hanford Waste Tank Declared Empty to Reg Standards

By ExchangeMonitor

Another Hanford C Farm radioactive waste storage tank has been declared empty to regulatory standards, with work to continue on two additional C Farm tanks. The 2010 consent decree between Washington state and the Department of Energy required the last of the 16 Hanford C Farm tanks to be emptied 15 months ago. The most recent tank to be emptied, C-102, allowed the Department of Energy to count a tank emptied in 2015. It is the 15th of 149 single-shell tanks emptied at Hanford, all but one of them in the C Tank Farm. The target is to have no more than 360 cubic feet of waste remaining in a tank, or about 1 inch if it were spread evenly over the bottom of the 530,000-gallon C Farm container. However, the state can agree that a tank is emptied to regulatory standards if the limits of technology are met. In the case of Tank C-102, about 2,100 cubic feet, or 15,500 gallons, remain that is “all pretty hard,” said Jim Alzheimer, a tank engineer for the Washington State Department of Ecology.

Some chunks that look like concrete plus sandy-looking particles remain, as the state agreed enough work had been completed, he said. The bottom of the tank is fairly clear, but rock-hard waste remains mounded by the tank walls. Two technologies were used to empty the tank before the state agreed DOE had done sufficient work. Work began in April 2014 using an enhanced-reach sluicing system to remove nearly 300,000 gallons of waste from the tank. The system was lowered through a riser into the underground tank and then a nozzle at the end of an extendable boom sprayed liquid waste to break up hardened material and move it toward a pump. A high-pressure water system also was used. The waste was transferred to a double-shell container to prevent leaks that have plagued single-shell containers at Hanford.

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