The US Hanford Site’s Waste Treatment & Immobilisation Plant (WTP) has achieved a commissioning milestone, producing more than 20 stainless steel containers of immobilised low-activity waste. “Each container represents tangible progress in the mission to protect the Columbia River and community,” said Mat Irwin, the Hanford Field Office Assistant Manager for WTP.
The Hanford site in Washington state, was used to produce plutonium over a 40-year period during WWII and the Cold War resulting in 56m gallons of radioactive and chemical wastes, which are now stored in 158 underground tanks. The US Department of Energy (DOE) contracted Bechtel National to design and build WTP, the world’s largest radioactive-waste treatment plant.
The plant uses vitrification technology, which involves mixing the waste with glass-forming materials and heating it to 2,100 degrees Fahrenheit inside large melters. This mixture is poured into stainless steel canisters to cool and solidify into a glass form that will be stable and impervious to the environment while its radioactivity dissipates over hundreds to thousands of years. Each container holds 6.6 tonnes of waste.
The Hanford WTP was originally intended to treat high-level and low-activity radioactive waste simultaneously. However, to begin treating waste as soon as practicable, DOE developed a sequenced programme that would treat low-activity waste first. DOE expects to begin treating high-level waste about a decade later.
The programme, called direct-feed low-activity waste (DFLAW), sends pretreated low-activity waste from Hanford’s Tank Farms, where the waste is stored, directly to the Low-Activity Waste (LAW) Facility at the WTP.
Several WTP infrastructure facilities, collectively called the Balance of Facilities (BOF), have been modified to support the LAW Facility and Effluent Management Facility (EMF), which processes the liquid secondary waste (effluent) generated by the LAW Facility. Up to five containers of waste a day can be produced at the LAW Facility, which will be disposed of at Hanford’s Integrated Disposal Facility.
The first pretreated tank waste was transferred to the LAW Facility in early October, when hot commissioning began. “Our team has turned progress into momentum, and we’re committed to carrying that forward through continued operations,” said Brian Hartman, WTP Project Director and Senior Vice President with Bechtel. During extended hot commissioning, the team will build production consistency and establish a steady rhythm of performance for safe and sustained operations.
