Experts will brief the public in May about the Department of Energy’s efforts to protect both Hanford workers and people nearby the site from a compound called acetonitrile: a toxic byproduct liquid radioactive waste treatment scheduled to begin by late 2023 at the former plutonium production site in Washington state.
“Subject matter experts” will be available during a virtual public hearing scheduled for May 10, a Department of Energy spokesperson at Hanford wrote in an email. The meeting is part of the agency’s request for a permit modification from its state regulator, the Washington Department of Ecology. DOE needs the modification before it can begin turning the toxic and radioactive liquid byproducts of Cold War plutonium production into glass-like logs using the Direct-Feed Low-Activity Waste (DFLAW) portion of Hanford’s Waste Treatment and Immobilization Plant.
DOE and its liquid-waste contractor, the Amentum-led Washington River Protection Solutions (WRPS), have long planned for acetonitrile to be present in liquid and vapor form during DFLAW operations, which following years of delay are set to begin by December 2023.
However, the state Department of Ecology only recently started asking Hanford questions about the potential for future acetonitrile exposures, and then only after the well-known environmentalist group Hanford Challenge contacted the state to voice concern about the toxic compound.
The week of April 4, DOE and WRPS started discussing the possibility of an acetonitrile vapor leak with the state Department of Ecology, said Ryan Miller, a spokesman for the state agency.
In early March, Ecology sent Hanford a detailed list of questions about acetonitrile, asking among other things whether the compound — to be captured downstream of DFLAW’s glass-making cylinders — could escape into the environment from its intended final resting place at the commercially operated Perma-Fix Northwest disposal facility in Richland, Wash.
Ecology sent its questions to Hanford a day after Hanford Challenge tipped off the state agency about a November 2021 DOE report that found, among other things, that WRPS initially did not consider the possibility that cleanup personnel downstream of the main DFLAW works could be exposed to vaporous acetonitrile. Hanford Challenge obtained the internal DOE report.
Acetonitrile, if ignited, gives off hydrogen cyanide fumes and potentially flammable vapors. Short-term effects from exposure can range from eye, nose and lung irritation to heart irregularities and death. Long-term, exposure could enlarge the thyroid gland and damage the liver, lungs, kidneys and the central nervous system.
A Hanford spokesperson said this week that the critical waste treatment systems described in the agency’s November 2021 report on WRPS have been designed to protect workers onsite from acetonitrile, and that acetonitrile left over from DFLAW will be safe at Perma-Fix Northwest.
“The system is designed to complete treatment to remove acetonitrile from the liquid effluent without exposing personnel to acetonitrile vapors,” the DOE spokesperson said. “Piping and equipment meet codes and standards for containing liquids and steam during all phases of operations [and the] design also incorporates the appropriate industrial hygiene controls and monitoring to ensure compliance with requirements.”
Initially, however, WRPS “did not evaluate or assess whether the concentration of acetonitrile in the worker breathing space, due to leakage from the pressurized portions of the system of vapor phase acetonitrile, would be below the 29 CFR 1910 limits” established by the Occupational Health and Safety Administration, according to the November 2021 DOE report.
But the concern about acetonitrile vapors on site “was addressed months ago,” the DOE spokesperson said this week
The Occupational Health and Safety Administration does not regulate nuclear facilities on DOE property.
