Hanford workers now are required to wear respirators to enter single-shell tank farms, an early result of an independent study of ways to better protect workers from chemical vapors.
An interim report on the study, led by the Savannah River National Laboratory in South Carolina, has not been made public.
However, Washington River Protection Solutions, the Department of Energy Hanford tank farm contractor, is reviewing a draft for accuracy, according to a memo to tank farm workers from Dave Olson, the contractor's president.
Based on what Olson called a "near-term recommendation" from the study team, Washington River Protection Solutions is requiring workers to wear either half-face or full-face respirators equipped with cartridges to filter the air they breathe when they enter single-shell tank farms. The type of respirator will be based on the potential risk of vapors.
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Information on the basis for the recommendation has not been released by the team, including to workers required to wear the respirators.
However, the single-shell tank farms have passive ventilation systems that release chemical vapors into the air. Hanford's newer double-shell tanks have active ventilation systems with fans that better dilute vapors released into the air.
Workers will continue to be required to use respirators in the double-shell tank farms if officials determine during work planning that there is a possible risk of chemical vapors. The risk increases if waste is disturbed, including to move it among tanks, and during certain weather conditions.
Respirators were required for a time this spring in some of the A-complex tank farms after possible vapors were smelled there, but that requirement was lifted after Washington River Protection Solutions went to a case-by-case evaluation system.
Since early spring, 49 Hanford workers have received medical evaluations after exposure to odors consistent with chemical vapors in or near Hanford's tank farms. The tanks hold waste left from chemically processing nuclear fuel to remove plutonium, and the headspaces of different tanks contain more than 1,000 chemicals, including mercury and benzene. The vapors often smell of the ammonia they contain.
Some of the workers who received medical evaluations had symptoms consistent with chemical vapor exposure. Those include headaches, dizziness, coughing and shortness of breath. Some former workers have developed serious long-term medical conditions attributed to vapor exposure.
Now workers are required to evacuate tank farms and move upwind if vapors are smelled or workers develop symptoms.
-- Annette Cary: 509-582-1533; email@example.com; Twitter: @HanfordNews