From 1944 until the 1980s, the United States used nuclear reactors to produce plutonium and other materials for nuclear weapons. Plutonium was extracted from the fuels used by these reactors by a chemical process known as reprocessing. As a result of these activities, after the shutdown of weapons production and of some reprocessing plants at the end of the Cold War, DOE retained an inventory of spent nuclear fuel that had not been reprocessed, as well as high-level waste—which is one of the byproducts of reprocessing. Weapons production and related defense activities—such as the reprocessing of the Navy’s spent nuclear fuel to produce new fuel, which also created high-level waste—are the source of about 87 percent of DOE’s inventory of spent nuclear fuel and almost its entire inventory of high-level waste. Because weapons production and reprocessing of the Navy’s spent nuclear fuel have ended, DOE’s inventories of this waste are largely fixed. DOE is also responsible for managing other nuclear waste from a variety of sources, including some active programs that continue to add to DOE’s inventory. For example, DOE is responsible for managing spent nuclear fuel from the Navy through the Naval Nuclear Propulsion Program, which is jointly operated by DOE and the Navy. The Navy uses nuclear-powered ships and submarines in carrying out its missions. The spent nuclear fuel removed from these vessels is the primary driver of increases in DOE’s inventory, but it totals only 1 percent of DOE’s spent nuclear fuel inventory. The remainder of DOE’s inventory of nuclear waste comes from various nondefense sources, including spent nuclear fuel from its own test and experimental reactors, reactors at U.S. universities, and other government research reactors; commercial reactor fuel acquired by DOE for research and development; and fuel from foreign research reactors. For example, DOE stores fuel debris from the Three Mile Island accident that occurred in 1979 at a commercial nuclear power plant. It also stores spent nuclear fuel from three commercial power demonstration projects, including from the first commercial-scale high-temperature gas-cooled reactor plant in the United States, at the Fort St. Vrain site. In addition, the United States operates a program to take custody of spent nuclear fuel from foreign research reactors, which supports a U.S. policy to prevent the proliferation of nuclear weapons; this program is scheduled for completion in 2019. DOE currently stores its inventories of nuclear waste at five DOE sites. In 1995, DOE decided to consolidate nearly all of its spent nuclear fuel from other sites at three primary locations—the Hanford Site, Idaho National Laboratory, and the Savannah River Site—for storage and preparation for permanent disposal. The exception to this consolidation decision is DOE’s Fort St. Vrain site, which stores less than 1 percent of DOE’s total inventory. In 1999, DOE decided to store its high-level waste where it was generated, at the same three primary sites. In addition, DOE manages a small amount of high-level waste that resulted from the relatively brief operation of the only commercial reprocessing plant ever run in the United States. This waste was generated between 1966 and 1972 from reprocessing spent nuclear fuel at a site near West Valley, New York, where DOE is now responsible for storing it. Some of the nuclear waste at these sites requires further processing and packaging before it can be safely stored over the long term or removed for final disposal. In the case of spent nuclear fuel, this generally means removing it from storage pools of water and packaging it in stainless steel canisters. The processing and packaging of high-level waste is vastly more complicated—a massive enterprise in which DOE is removing waste from storage tanks and transferring it to treatment facilities. For example, at the Savannah River Site, DOE is vitrifying high-level waste by mixing it with a glass-forming material, melting the mixture into glass, and pouring it into stainless-steel canisters to harden. Across all sites, DOE expects to eventually produce about 20,000 canisters of solidified high-level waste. Once the wastes are stabilized, removing them from the sites would require a destination where they could be stored or permanently disposed of and a decades-long shipping campaign to get them there. Appendix I describes how the sites are in different stages of preparing spent nuclear fuel and high-level waste for final disposal. In the meantime, DOE manages many types of storage facilities, as illustrated in figure 1, of widely varying ages and conditions. For example, DOE has generally been moving spent nuclear fuel from wet storage in pools of water, designed to cool the fuel and provide radiation protection, to dry storage. Dry storage has numerous configurations, including underground storage vaults, only some of which are covered by a building, and casks on an outdoor pad or a railroad car. Overall, these storage facilities vary from aging to almost new; for instance, they range from a 1950s building at the Idaho National Laboratory to a high-level waste canister building constructed in 2005 at the Savannah River Site. DOE operates these five sites under a legal framework that includes self- regulation, as well as regulation by federal agencies and states. In contrast to the commercial nuclear industry’s sites, which are regulated by NRC, DOE generally operates under its own regulations for nuclear safety at its sites. In addition, DOE’s treatment, storage, and disposal of radioactive and hazardous wastes are governed by a number of federal and state laws, including the Resource Conservation and Recovery Act of 1976 (RCRA), as amended, which regulates the management of hazardous waste from generation to disposal. The Federal Facility Compliance Act of 1992 amended RCRA to require federal agencies, including DOE, to develop waste treatment plans for their sites that contain mixed wastes—certain wastes with both radioactive and chemically hazardous materials. For example, high-level waste is sometimes considered a mixed waste because it contains highly corrosive, organic, or heavy metal components that may be regulated under RCRA. These plans are approved by states that the Environmental Protection Agency (EPA) has authorized to administer RCRA or by EPA in states that have not been so authorized. Activities carried out under these plans are often governed by compliance agreements between DOE, EPA, and the states (state agreements), which regulate and oversee the activities. State agreements establish the scope of work to be performed at given sites, as well as “milestones”—specific dates by which these activities should be achieved. The agreements may also impose monetary or other penalties for missing milestones. Milestones may cover actions to treat, store, and dispose of hazardous wastes located at the DOE sites. Agreements differ by state. Some cover virtually all cleanup activities at a site, while others cover just a portion. These activities may include soil and groundwater remediation, low-level radioactive waste disposition, and special nuclear material consolidation; in this report, we focus on state agreement cleanup activities involving spent nuclear fuel and high-level waste. States and DOE can negotiate to amend or modify the agreements, including extending or eliminating milestones. State agreements may be created in at least four ways. First, states may enter into Federal Facilities Agreements (also known as Tri-Party Agreements) with DOE and EPA, which implement the Comprehensive Environmental Responsibility, Compensation, and Liability Act of 1980 (CERCLA) and RCRA, as well as state hazardous waste law requirements to set the cleanup schedules at sites. CERCLA, among other things, authorizes EPA to compel responsible parties to initiate cleanup activities at hazardous waste sites. Second, states may take legal action against DOE seeking review of its compliance with the National Environmental Policy Act, which can result in settlement agreements between the parties and may outline activities and milestones. Third, Congress may address the management of wastes at a specific site. Finally, federal government officials may enter into agreements with states concerning DOE-managed radioactive waste, which may include specific cleanup milestones. The five states with DOE sites storing nuclear waste have agreements with DOE, and in one case with the Navy, regarding how nuclear waste will be managed. However, only the agreements with Colorado and Idaho would be affected by a termination of the Yucca Mountain repository because only those agreements specify dates for removing the waste from the DOE sites. Each DOE site falls under at least one state agreement that specifies certain treatment, storage, or disposal activities for high-level waste, spent nuclear fuel, or both. The agreements with four sites deal with the safe storage and treatment of high-level waste. (DOE’s site in Colorado, does not store any high-level waste; it stores only spent nuclear fuel.) In addition, state agreements for some DOE sites focus on the storage of spent nuclear fuel or its removal from the states. Major state agreements at each site are as follows: Idaho National Laboratory. DOE and the Navy are party to a 1995 settlement agreement and consent decree (the Idaho Settlement Agreement), entered into the United States District Court for the District of Idaho, to settle a lawsuit brought by the state. The agreement commits DOE to prepare its high-level waste for shipment out of Idaho for disposal. The agreement also contains provisions for managing spent nuclear fuel. Specifically, it requires DOE and the Navy to move their spent nuclear fuel from storage in pools of water to dry storage—given state concerns that the water pools might leak and radioactively contaminate the underlying groundwater—and later to move the spent nuclear fuel out of Idaho. Fort St. Vrain Site. In 1996 the Governor of Colorado signed an agreement with the Assistant Secretary for Environmental Management at DOE, referred to as the “Agreement Between the Department of Energy and the State of Colorado Regarding Shipping Spent Fuel Out of Colorado.” The agreement states that DOE is committed to shipping its spent nuclear fuel stored at Fort St. Vrain out of Colorado.