What is High-Level Waste?
High-level radioactive waste is the highly radioactive material resulting from the reprocessing of spent nuclear fuel. The high-level radioactive waste (HLW) is currently stored at the Hanford Site, the Savannah River Site, the Idaho National Laboratory, and at West Valley, New York. The Hanford Site reprocessed defense reactor fuels and generated about 245,000 m3 of HLW to recover the plutonium, uranium, and other elements for defense and other federal programs. The Savannah River Site also reprocessed defense reactor fuel to recover the same materials as did Hanford, and produced approximately 122,000 m3 of HLW. The Idaho National Laboratory reprocessed spent fuels from naval propulsion reactors, test reactors, and research reactors to recover uranium and generated approximately 30,000 m3 of HLW. A commercial fuel reprocessing plant located at West Valley, New York operated from 1966 through 1972 and reprocessed approximately 660 metric tons of commercial spent nuclear fuels to recover the unused uranium.
What does high-level waste look like and how is it handled and stored?
HLW resulting from the reprocessing of spent nuclear fuel is in a liquid form and stored in underground metal storage tanks at the four sites mentioned above. Between 1960 and 1997, the Idaho National Laboratory converted all of their HLW into a solid waste form called calcine (a granular solid with the consistency of Tide soap) using a process call fluidized bed calcination. These solids are stored retrievably on-site in stainless steel bins (like grain silos but smaller) within concrete vaults.
How will the HLW be handled and disposed of at the repository?
To protect the public and environment, HLW in a liquid form is not allowed at the repository. At West Valley, the HLW was mixed with glass frit (similar to sand) and solidified into a borosilicate glass using a process call vitrification. The borosilicate glass is poured into stainless steel canisters approximately 24 inches in diameter and 10 feet in length. West valley has converted all their HLW into 275 canisters of borosilicate glass that are stored at the facility until the repository is operational. As of July 2008, Savannah River Site has produced approximately 2,500 24-inch by 10-foot borosilicate glass canisters using the same vitrification process as West Valley. The Savannah River Site vitrification process continues to be operated and additional canisters will be produced. Savannah River Site is also storing their HLW borosilicate glass canisters on-site awaiting operation of the repository. Hanford Site also plans to convert their HLW into borosilicate glass using the vitrification process in a facility called the Waste Treatment Plant. Their HLW canisters would be 24 inches in diameter and 15 feet in length. As of 2008, the construction of the Waste Treatment Plant is over 40% completed and it is scheduled to be operational in 2019.
DOE is currently evaluating various options to determine how calcine at the Idaho National Laboratory should be packaged before it is sent to the repository. Once the waste form has been determined, the calcine would be placed in 24-inch by 10-foot stainless steel canisters.