Report: Brief, Intense Exposures to Blame for Workers’ Health Symptoms at Hanford Tank Farms

A report released Oct. 30 includes recommendations for improving the industrial hygiene programs at the U.S. Department of Energy’s Hanford Site in Richland, Wash. Concerns about chemical vapors at Hanford reached a peak this past spring when more than two dozen workers received medical attention following exposures to vapors emanating from waste storage tanks or other sources. According to the report, the underground storage tanks at Hanford house 53 million gallons of concentrated radioactive and chemical waste that is the byproduct of the processing and “reprocessing” of nuclear materials for U.S. weapons programs. The report was issued by a team of independent experts, including several AIHA members, who were part of the Tank Vapor Assessment Team (TVAT) led by the Savannah River National Laboratory. The team was formed at the request of Washington River Protection Solutions (WRPS), the contractor responsible for management and cleanup of nuclear and hazardous waste currently stored at Hanford.

While information provided to TVAT indicated that the concentrations of chemicals reported as time-weighted averages were not consistent with the health symptoms reported by the tank farm workers, the team’s analysis determined that there was a causal link between tank vapor exposures and the adverse health effects experienced by employees, according to team lead Dr. Bill Wilmarth, senior advisory scientist at Savannah River National Laboratory. The team hypothesized that vapors coming out of tanks in high concentration plumes sporadically intersected with the workers’ breathing zones, resulting in brief but intense exposures to some workers.
“The team used a combination of testimony from tank farm workers, engineering data, and computational modeling to support the plausibility of a transient, acute exposure scenario,” Wilmarth said. “Verifying and quantifying transient acute exposure requires an approach different from traditional design of full-shift industrial hygiene monitoring. The team made recommendations for controlling and detecting these emissions, and protecting the work force.”
TVAT’s report includes ten overarching recommendations and more than 40 supporting recommendations that the team believes will reduce the likelihood of occupational exposures to tank vapors. The recommendations include:
  • validate and enhance chemical characterization by proactively sampling the head space of tanks
  • utilize real-time personal detection and protective equipment technologies specifically designed to protect individual employees
  • accelerate implementation of tailored engineering technologies to detect and control vapor emissions and exposures
  • implement measurable benchmarks to assure operational and cultural parity among chemical vapor, flammability, and radiological control programs
  • investigate and pursue external research opportunities and partnerships to address data and technology gaps related to vapor exposure, effects, and mitigation
AIHA members Andrew Maier, PhD, CIH, DABT; Tom Armstrong, PhD, CIH; John L. Henshaw, MPH, CIH; Matthew H. Le, MPH, CIH, CSP; Michael Jayjock, PhD, CIH; and Jim Rock, PhD, CIH, PE, were part of TVAT.
The full report is available on the Savannah River National Laboratory’s website.
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