Six workers at the Hanford nuclear reservation reported an onion-like smell Wednesday afternoon that may have been chemical vapors.
None of the workers reported symptoms and all declined precautionary medical evaluations, according to tank farm contractor Washington River Protection Solutions.
The workers were near a changing trailer outside the TX Tank Farm preparing for routine electrical maintenance when the smelled the suspicious odor. They were not wearing supplied air respirators because they were outside of the fence line of the tank farm.
Workers left the area after the odor was reported shortly after 2 p.m. and access was restricted. No work that would disturb waste, which can increase the chance of chemical vapors being emitted, was being done.
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The vapors are associated with waste held in underground tanks.
The last report of suspicious odors near the tank farm was on June 13, when five workers received medical evaluations after they and others smelled a suspicious odor outside the A Tank Farm. All were released to return to work.
Hanford workers previously have reported symptoms such as shortness of breath, coughing and a metallic taste in their mouth. They are concerned that inhaling chemical vapors could lead to serious neurological and respiratory illnesses.
The Department of Energy and its tank farm contractor are being sued in federal court by the state of Washington, Hanford Challenge and union Local 598 for better protection of Hanford workers from chemical vapors.
More than 50 workers received medical checks in 2016 because of potential exposure to chemical vapors and were cleared by the site's occupational health provider to return to work.
Most of the incidents occurred before Washington River Protection Solutions began requiring supplied air respirators for most work inside tank farms in response to a stop-work order issued by the Hanford Atomic Metal Trades Council.