Contractor Washington River Protection Solutions is ending fiscal 2017 with two successful evaporation campaigns that have freed up enough of the Hanford Site’s limited double-shell tank space to store 525,000 gallons of waste.
Material from 149 single-shell tanks is being emptied into the site’s 27 double-shell tanks at Hanford that remain in service until the Waste Treatment Plant can begin vitrifying up to 56 million gallons of waste left behind by decades of plutonium production at the Energy Department site in Washington state.
During the most recent operating run of the 242-A Evaporator in central Hanford – from Aug. 25 to Sept. 8 – some 315,000 gallons of excess liquid tank waste was removed. An earlier operating run from July 1 to 13 reduced the volume of waste by 210,000 gallons. The space created this summer is equivalent to about half of a double-shell tank.
The 242-A Evaporator began operating in 1977, but went offline for about four years for extensive improvements after an operating campaign in 2010. In late 2014 and 2015, the evaporator freed up space for about 2 million gallons of waste and in 2016 freed up space for about 300,000 gallons of waste. Successful operation of the 242-A Evaporator is central to DOE’s plans to meet its court-enforced consent decree obligations to empty 19 single-shell tanks without adding double-shell tanks.
The 242-A Evaporator heats liquid waste from double-shell tanks under vacuum pressure so it will boil at a temperature of about 125 degrees Fahrenheit. The liquid vapor from the boiling waste is captured, condensed, filtered, and sent to the Effluent Treatment Facility for treatment and disposal. The remaining concentrated waste is returned for storage in a double-shell tank.
A new exhaust stack was installed at the 242-A Evaporator before operation of the plant this summer to help protect workers from exposure to chemical vapors associated with tank waste. The new stack raised the discharge point 48 feet to a height of 111 feet. WRPS also worked with union leadership to develop a comprehensive industrial hygiene control strategy for the recent plant operation.
“Area direct-reading instrumentation readings in the general work areas during the campaigns were well below action and occupational exposure limits,” said Mark Lindholm, WRPS president, in a message to employees this week.
