Concerns over chemical vapors from an underground tank have stopped work to retrieve radioactive waste from Tank C-104, the only leak-prone tank currently being emptied at Hanford.

A Hanford worker has been diagnosed with a medical issue after several workers smelled fumes, and a determination has not been made about whether the medical problem could be linked to the vapors.

Late at night Jan. 25, workers who were in a control trailer for the work outside the C Tank Farm fence at Hanford came outside and smelled a strong odor linked to vapors vented from the tanks, said Fred Beranek, director of environment, safety, health and quality at Washington River Protection Solutions.

Smelling vapors is not unusual, and workers who have any symptoms are required to report for medical care, he said.

Because AdvanceMed Hanford was closed, the workers were driven to Kadlec Regional Medical Center in Richland, were checked out that night and then were allowed to return to work for their next shifts by Advance-Med Hanford. Symptoms were typical of vapor exposure, including watery eyes, throat irritation or a metallic taste in the mouth, Beranek said.

During the week, several more workers who developed symptoms, all apparently from the same January shift, also went to AdvanceMed Hanford to be checked, he said.

On the start of the next work week, Feb. 1, a worker called a stop to work, using a system extended to any Hanford worker who believes there is a safety issue, because of the number of employees who had reported symptoms.

After calling in management, experts in the tank farm vapors and Hanford Atomic Metal Trades Council, or HAMTC, safety representatives, Washington River Protection Solutions and HAMTC leaders agreed that it was safe for work to resume two or three hours later, Beranek said.

In addition to talking to workers, they looked at data and monitoring results, concluding that chemicals in the vapor were below levels believed to be harmful.

However, on Tuesday Washington River Protection Solutions was notified by AdvanceMed Hanford that one of the workers exposed to vapors had a medical issue that would require the worker to stay out of areas with organic vapors. Washington River Protection Solutions declined to discuss what the medical issue was because of medical privacy laws, but such a restriction would be ordered for a lung issue.

"That was unusual," Beranek said. It's the only time since Washington River Protection Solutions took over the tank farm contract 15 months ago that a worker who smelled vapors had not been routinely released back to work.

An hour later work was stopped to empty Tank C-104.

The stop remains in effect until Washington River Protection Solutions knows more about whether vapors could have harmed the worker.

Monday it plans to put together a team that could include union workers, engineers and industrial hygienists to look at possible changes to better protect workers.

For at least six months Washington River Protection Solutions has been working on improved protection, such as roping off more areas, increasing monitoring and sampling, requiring chemical hazard refresher courses and considering changes such as extending the vent stacks from tanks higher into the air, Beranek said.

Now the stack that vents from Tank C-104 is about 17 feet above the ground. The control trailer where workers got strong vapor smells is slightly uphill from the tank about 100 yards away and the Tri-Cities was in one of its frequent winter weather inversions with no wind when the incident occurred.

The Department of Energy is concerned that employees are having chronic symptoms at work, even if they are not acute, and wants to find the right combination of safety precautions to prevent them, said Shirley Olinger, manager of the DOE Hanford Office of River Protection.

The tank farms already use a lower limit for chemical exposure than is used in industry and Washington River Protection Solutions has further adopted a policy of keeping exposure as low as reasonably achievable, she said. That's a common practice for radiation protection, but the industrial practice for chemicals usually is to keep exposure below a threshold that would cause harm.