Treatment of the Hanford Site’s liquid radioactive waste will produce toxic vapors from a substance called acetonitrile, the Department of Energy said last year in an internal report, a compound that would be unsafe for workers and, according to an environmental group, potentially threatening to people and animals living near the site.
The week of April 4, DOE and Washington River Protection Solutions, the agency’s Amentum-led tank farms contractor at Hanford, started discussing the possibility of an acetonitrile vapor leak with the Washington State Department of Ecology, said Ryan Miller, a spokesman for the state agency.
The State Department of Ecology asked DOE for more information about the vapors on March 2, a day after the Seattle-based environmental watchdog, Hanford Challenge, tipped off the state agency about the Aug. 27, 2021 DOE report. In the report, a copy of which Hanford Challenge obtained, DOE said it had looked at the possibility of a liquid acetonitrile spill on site but had not yet examined the ramifications of an acetonitrile vapor leak.
In an email on March 28, a DOE spokesperson said the possibility of a vapor leak “was addressed months ago with the design process” for some of the Hanford infrastructure designed to help the agency safely solidify the liquid, radioactive plutonium-production biproducts stored in the sites underground tanks.
However, neither DOE nor its contractor would elaborate on the 2021 internal memo that raised concerns about acetonitrile: a substance that will be used to treat the nuclear waste before it is turned into glass logs at Hanford’s Waste Treatment and Immobilization Plant.
The first part of the long-delayed plant, dubbed “direct-feed low-activity-waste,” or DFLAW, was due to open in late 2023 and begin solidifying the least radioactive and least complex Hanford tank wastes.
Before entering the Waste Treatment and Immobilization Plant, these wastes — byproducts of Cold War plutonium production — will be run through a separate Pretreatment Facility. The pretreatment and the acetonitrile are the subject of the 2021 memo.
Acetonitrile, which exists in liquid and vapor forms, is easily ignited by heat, sparks or flames. When ignited, it 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.
In addition to the hazards posted to workers on site, acetonitrile might be present in a waste byproduct of the DFLAW process, said Tom Carpenter, the recently retired executive director of Hanford Challenge. This byproduct could be disposed of in a waste facility operated by Perma-Fix and located within five miles of thousands of people, Carpenter said.
Meanwhile, DOE and Washington River Protection Services, which designed the Waste Treatment and Immobilization Plant’s pretreatment equipment, said in emails that the anyone can ask questions about the vapor issue during a public hearing scheduled for May 10. The hearing concerns permits for acetonitrile-related equipment at the glassification plant. Written public comment is being accepted through June 4.
Editor’s note, April 15, 2022, 9:37 a.m. Eastern time: the story was corrected to show that an environmental group, not the internal DOE report, raised concerns about acetonitrile exposure to people other than Hanford site workers, and to animals.