Washington River Protection Solutions (WRPS) has resumed work to empty waste from Hanford Site Tank AY-102 as it faces a March 4, 2017, retrieval deadline under a settlement agreement with Washington state.
The Department of Energy’s Hanford tank farm contractor halted work on the tank leaking waste between its two shells this spring to change out the retrieval systems. Work did not restart as planned as soon as September because DOE and WRPS were prohibited by a federal judge from performing work that disturbed waste and could increase the potential for releases of chemical vapors from the tanks.
U.S. District Judge Thomas Rice lifted the prohibition last month, determining that requirements for supplied air respirators should adequately protect workers until a worker-safety lawsuit brought by Washington state and other plaintiffs is decided at a trial scheduled for October 2017. To further protect workers, WRPS has planned the work for night and weekend shifts when few Hanford workers are on site.
Before work began meetings were scheduled with nearly every worker on the site to explain the waste retrieval operations. Roads into the 200 East Area, which includes the AY Tank Farm, are barricaded and reader boards warn that only authorized personnel should enter when waste disturbing work is underway at Tank AY-102. A requirement that workers wear supplied air respirators has been expanded, as a precaution, to the exhaust stacks associated both with Tank AY-102 and the sturdier double-shell tank into which its waste is being pumped.
Work has been slowed by bad weather, with the site closed at times recently due to snow and icy roads. On some other nights and weekend days the temperature has been too cold for retrieval to proceed.
Retrieval work started the second weekend of the month, but shut down within minutes because of an equipment issue. A few days later, workers used sluicers to move waste toward a central pump in the enclosed tank for retrieval. WRPS expects to remove the first measurable amount of waste from the tank in this retrieval campaign this weekend.
Hanford workers emptied most of an estimated 800,000 gallons of waste from the tank in March and April, but the sluicing system then being used could not reach the last 40,000 gallons of sludge. The two conventional sluicers used in the spring have been removed and replaced with four extended-reach sluicers that are more robust and have a longer reach than the older sluicers, said Doug Greenwell, WRPS manager of tank waste retrieval.
“Our team has spent months preparing for this final phase of AY-102 retrieval,” said Mark Lindholm, WRPS president, in a message to employees this week.
More waste began to leak into the space between the shells of Tank AY-102 during the emptying campaign last spring. The issue was expected and will no doubt occur again in the current retrieval campaign, Greenwell said. A pump is installed in the space between the tanks to remove waste as it accumulates. No waste is known to have escaped from the outer tank into the environment. The tank had a slow leak into the space between its shells for years before DOE and Washington state reached a settlement agreement requiring it to be emptied enough by March 4 to determine the cause of the leak. Emptying the tank will allow for a decision on whether the tank must be closed or could be repaired and returned to service, Greenwell said.
