In southeastern Washington state, the U.S. Department of Energy, along with primary contractor Bechtel National, Inc., is designing, building and will soon be operating the world’s first chemical waste processing facility capable of both separating radioactive liquid waste and turning it into a stable, glass form suitable for permanent, safe disposal.
The Waste Treatment & Immobilization Plant Project covers about 65 acres on the Hanford Nuclear Reservation. Hanford is home to one of the largest environmental cleanup efforts in the world. The WTP will process and immobilize the majority of Hanford’s 56 million gallons of radioactive and chemical waste, a byproduct of national defense plutonium production efforts during World War II and the Cold War era.
Today, more than 63% complete, over 3,000 employees are focused on constructing the plant and preparing for operations.
Design of the plant will be complete by 2013; construction will be complete just three years later, in 2016, and start-up of plant systems will begin. In 2019, all facilities and systems will be fully operational and begin the process of vitrifying tank waste.
Vitrification is accomplished by mixing the waste with glass forming materials in a high temperature environment. As the materials are heated to 2100 degrees F, the waste and glass forming materials become red hot and bond together. The “liquid glass” is poured into stainless steel canisters to cool. Once the waste has cooled, the now-solid (vitrified) waste within the canisters can be permanently and safely disposed of. The most hazardous waste will be buried in a national repository, while less dangerous wastes may be disposed of at the Integrated Disposal Facility (see Integrated Disposal Facility link) here at Hanford.
The nuclear and chemical wastes will be delivered from the underground storage tanks (see Tank Farms link) to the Vit Plant through a series of underground transfer lines. Called “pipe in pipe,” the system ensures that there are no leaks of materials during the transfer.
The waste will first enter the Waste Treatment Plant complex in the Pretreatment Facility. The largest of the facilities in the complex, it will be the equivalent of 1 ½ football fields in length (540 ft.), over 70 yards wide (215 ft.), and twelve stories high (120 ft.). It will encompass more than 13.9 million cubic feet of space and contain 100 miles of piping. The Pretreatment Facility will separate the tank waste into low-activity and high-level waste streams for the Low-Activity Waste and High-Level Waste vitrification facilities. The Pretreatment Facility concentrates the waste by first removing any excess water. After that, the solids are filtered out using ultra-filtration technology, and an ion exchange process removes the remaining soluble, highly radioactive material.
Chemical Processing Operations
The Analytical Laboratory, also known as the Lab, is a critical component for operations at the WTP. The Lab’s key function is to ensure that the final, vitrified glass product meets all regulatory requirements and standards.
It’s expected the Lab will analyze about 10,000 waste samples each year. When waste initially arrives at the WTP, the Lab will be used to determine the correct proportions of waste and glass forming materials that need to be mixed together. Determining the right “recipe” will produce a consistent vitrified waste product. For LAW, the mixture is anticipated to be about 20% waste and 80% additives; HLW’s expected “recipe” for producing consistent, vitrified high-level waste is 30% waste and 70% additives. The Lab will continue to sample waste throughout the Vit Plant’s operations, making adjustments where needed so that all wastes will have consistent properties and meet accepted regulatory requirements.
The low-activity waste is primarily in liquid form that has a relatively small amount of radioactivity. Referred to as LAW (low-activity waste), these wastes will be sent to the Low- Activity Waste Vitrification Facility. The high-level waste (HLW) is primarily in the solids which have formed in the waste. High-level waste contains much more radioactivity than the low-activity waste does, and will be treated at the High-Level Waste Vitrification Facility. As with the Pretreatment Facility, both buildings required to process the LAW and the HLW are massive. Each will be longer than a football field (300 ft.) and rising at least six stories (90 ft.) tall.
The process of vitrifying high-level waste and low-activity waste is basically the same, but the wastes are processed in different facilities. After processing within the Low-Activity Waste Vitrification Facility, the molten glass is poured into stainless steel containers that are seven feet tall and four feet in diameter. Each full container will weigh more than seven tons. At the High-Level Waste Vitrification Facility, the vitrified waste will be poured into stainless steel canisters that will be 15 feet tall, two feet in diameter, and weigh four tons.