The Hanford Waste Treatment Project (WTP) in Washington State has one of the larger concentrations of radioactive waste in the world. The waste is the legacy of 45 years of plutonium production for nuclear weapons, which began with the Manhattan Project in the 1940s and continued throughout the Cold War.
At Hanford, 53 million gallons of high-level radioactive waste, 60 percent by volume of the nation's total, is stored in 177 old and deteriorating underground tanks just seven miles away from the environmentally sensitive Columbia River. An estimated one million
gallons of waste have already leaked from 67 of the facility's oldest tanks. Radioactive waste has been detected in the groundwater that flows to the Columbia, endangering the river habitat and the health of millions of Washington and Oregon residents who
live downstream.
The West's mightiest river, the Columbia, is threatened by the leaking radioactive waste at the Hanford site. At risk are the river's habitat and the health of millions of residents who live downstream.
To remediate the hazard, the Department of Energy (DOE) commissioned a project in which the high-level radioactive waste is treated and converted to glass logs in a process known as vitrification. Vitrification is currently considered the most effective treatment process for this type of contamination, as it produces a durable and stable form that fully incorporates and immobilizes radioactive waste. Similar projects have been successfully employed in the United States, France and England.
Once immobilized, the high-level radioactive portion of the WTP waste will be temporarily stored at the Hanford site in stainless steel canisters until it can be shipped to a federal geologic repository for permanent disposal. The low-level radioactive portion of the waste will be stored on-site.
The DOE's Office of River Protection awarded a contract to Bechtel(r) National, Inc. in December 2000 to design, construct and commission the Hanford Waste Treatment Plant. It is estimated that the buildout of the WTP will cost the government $5.7 billion and take up to 10 years to complete. The WTP project currently under construction is a massive undertaking that is now the U.S. government's largest capital construction project. When completed, it will also be the world's largest vitrification facility. The project includes three major nuclear facilities - the first one for pretreatment, a second for the low-activity waste vitrification, and a third for high-level waste vitrification.
From construction to final vitrification, the WTP project is a major feat of modern engineering. A significant portion of the project focuses on how the waste is handled so that worker safety is never breached while the overall goal of isolating and treating the waste is achieved.
Valves and valve automation products designed for handling radioactive waste are carefully specified and manufactured to meet strict government requirements. This ensures that standards conform to the critical demands in severe services associated with nuclear applications. To meet these stringent requirements, valve solutions in this field must sometimes rely on devices used outside of convention and history to become ideal solutions. Such was the case when product engineers and specialists at Flowserve Corp. designed innovative valve and automation solutions for the control, isolation and treatment of radioactive waste slurries at the Hanford Waste Treatment Project.
In the first part of the waste treatment process, specialized valves were needed for installation in containment vessels called "bulges." Each bulge is roughly the size of a small swimming pool and is designed to contain all the pumps, valves and piping required to transfer the radioactive liquid waste slurry from the existing underground storage tanks to the waste pretreatment building for processing.
The pretreatment system combines a filtration process that removes the solids from the waste slurry and an ion-exchange process that then removes the soluble high-level waste from the remaining liquid. Guidelines for this part of the project required manual and automated valves that could be operated and repaired from outside the containment bulges to ensure worker safety and radioactive containment. All bulge valves were subject to NQA-1 inspection and documentation to meet strict DOE specifications. Bulge valve actuators and positioners were also specified to be mounted outside the containment barrier of each bulge.
For more information, visit www.flowserve.com.
Report compiled by Clyde Witt.
