56 million gallons of Hanford's high-level radioactive waste is contained in 177 underground waste tanks. More than a third have leaked, and nearly all are beyond their design-lives. 28 of the tanks are double-shell tanks and 149 are single-shell tanks.
At least one million gallons of high-level radioactive waste has leaked into the soil and groundwater under the tanks. Sixty-seven tanks have been known to leak in the past, one double-shell tank has failed and is currently leaking waste into the space between the two shells of the tank.
The leaked waste is a huge cleanup challenge. The tanks are able to accommodate between 55,000 to 1,000,000 gallons of waste and are buried about 7-8ft. under the soil. The majority of the leaked waste is under the tanks in the vadose zone, the area between the surface of the soil and the groundwater, and some of the waste has reached the groundwater.
In addition to the waste inside the tanks, waste was also deliberately discharged to the soil. An estimated 120 million gallons of waste from the Hanford tanks were directly ejected into the soil in this manner.
The tanks hold waste created during the process of extracting plutonium from spent fuel, and contain both radioactive and chemical waste. It has also separated out into sludge, liquid, solids, and vapors. Its complexity, along with the fact that it is highly radioactive, caustic, and toxic, makes it particularly difficult and dangerous to treat.
The only plan for dealing with Hanford's tank waste is to immobilize the waste in glass through a process called vitrification. The Waste Treatment Plant (WTP) is being built for that purpose, however it is riddled with design problems, delays, and an escalating cost. It is also not designed to have the capacity to treat all of hanford's tank waste, so additional vitrification capacity, i.e. new facilities, will be required.
Potential short-term fixes include building new tanks to provide space for waste in leaking tanks; building barriers over some of the tank farms to prevent water from further mobilizing the contamination until the waste can be pumped out of the tanks; and looking at other treatment technologies.
There are no estimates available from the DOE about how much the WTP will cost, but taxpayers have already spent billions of dollars so far, and costs may exceed $20 billion for design and construction alone. Operational costs may be as high as $45 to $60 billion. The WTP needs to work safely and effectively to remove and stabilize the waste from Hanford’s aging tanks. Efforts to build a vitrification plant started in the late 1990’s and have stopped and started repeatedly. The latest effort (the fourth attempt) was initially scheduled to operate in 2019, but it is now not expected to reach full capacity until 2036 or later. Hanford Challenge has called for the dismissal of the contractor and for work at the WTP to stop while new tanks are built, and while an independent review both evaluates whether the plant can be salvaged and investigates alternatives.
Decisions about what to do with the tanks themselves and the waste that is difficult to remove have yet to be made. It will be extremely challenging to remediate the vadose zone contamination without removing the tanks. If we want to protect future generations from that waste, it must be removed.
Working around the tanks is a hazardous job. Exposure to toxic chemical vapors that vent from the tanks is a major concern. Since March 2014, over 100 workers suffered vapor exposures serious enough to seek medical evaluation. Serious reforms are needed to protect workers from these hazards and provide them with good medical treatment.
