The Hanford tank farm contractor and a union group have agreed to lift a blanket requirement that workers wear supplied air respirators, but only under some initial limited conditions.
Workers have not been allowed to enter Hanford tank farms unless they wear supplied air respirators since the Hanford Atomic Metal Trades Council, or HAMTC, an umbrella group of 15 Hanford unions, issued a stop work order in June.
Officials were concerned that breathing in chemical vapors associated with waste held in underground tanks could seriously damage workers’ health.
HAMTC and the tank farm contractor, Washington River Protection Solutions, agreed in late August that workers would not enter the fences around tank farms where waste is stored unless they wear supplied air respirators.
But they also agreed to lift the requirement if tests showed air-purifying respirators could protect workers from vapors.
The restriction has been lifted, initially starting March 14, for limited work in the group of tanks called the AP Tank Farm. That tank farm also is the one where the tank farm contractor is testing a suite of advanced chemical vapor monitoring and detection equipment.
Workers may wear full-face air-purifying respirators equipped with cartridges to filter out chemical vapors, if no work is being done that disturbs waste or intrudes into tanks, workers were told in a message Thursday signed by both Mark Lindholm, president of Washington River Protection Solutions, and Dave Molnaa, HAMTC president.
Work on the air-purifying respirators, at least initially, may include operator rounds, routine radiological surveys, preventive maintenance, visual inspections, equipment calibrations and setting up and taking down equipment for jobs.
As is Hanford policy, any worker not comfortable with the less-restrictive respirators will be allowed to use a supplied air respirator unless it would pose additional safety hazards.
No worker has reported a possible exposure to chemical vapors while wearing the supplied air respirators, but the system is cumbersome and heavy. Hanford officials said the gear, including the air bottles workers carry on their backs, weighs about 35 pounds.
They also increase the time required to perform tasks by about 50 percent, the Department of Energy has said.
“The joint decision between WRPS and HAMTC to allow workers to select these air-purifying filter cartridges is based on scientific evidence,” said the message from Lindholm and Molnaa.
Cartridges were tested under extreme conditions in areas where workers would not be breathing in chemical vapors, such as in the head space of tanks or as the vapors come out of ventilation stacks.
Air was sampled before and after it passed through the cartridges used on air purifying respirators and sent to an accredited laboratory. Pacific Northwest National Laboratory has reviewed results on how well the cartridges performed and for how long.
Conclusions then were reviewed by a team of experts selected by HAMTC, who agreed that limited use of air purifying respirators in the AP Tank Farm is appropriate.
Tests of the cartridges are continuing, with any further decisions to modify supplied air respirator requirements to be made on a tank farm by tank farm basis.