Nuclear research reactors are used for training and research purposes throughout the world. Research reactors are generally smaller than nuclear power reactors, ranging in size from less than 1 to 250 megawatts compared with 3,000 megawatts generated by a typical power reactor. In addition, unlike power reactors, many research reactors use HEU fuel instead of LEU in order to produce the appropriate conditions in the reactor cores for conducting a wide variety of research. DOE has identified 161 operating research reactors that were designed to use HEU fuel and has included 105 of them in the reactor conversion program. The research reactors included in the program are spread out among the United States and 40 other countries, including Canada, France, Germany, and Russia (see fig. 1). In addition to the 105 research reactors covered under the reactor conversion program, DOE has targeted six medical isotope producers that use HEU as an ingredient in their production processes, including four large medical isotope producers located in Belgium, Canada, the Netherlands, and South Africa. For a variety of reasons, DOE has excluded from its reactor conversion program 56 research reactors that use HEU fuel, including 9 in the United States. Some of the reactors are used for military or other purposes, such as space propulsion, that require HEU. Others are located in countries such as China that so far have not cooperated with the United States on converting their reactors to LEU. Finally, the time and costs associated with developing LEU fuel for some of the reactors may exceed their expected lifetime and usefulness. The United States has historically provided nuclear technology to foreign countries in exchange for a commitment not to develop nuclear weapons. Starting in 1953, the Atoms for Peace program supplied research reactors and the fuel needed to operate them to countries around the world. The research reactors supplied by the Atoms for Peace program initially used LEU fuel, but many countries gradually switched from LEU to HEU in order to conduct more advanced research. In addition, HEU fuel could remain in the reactor core longer and was less expensive than LEU fuel. By the late 1970s, most research reactors were using HEU fuel and the United States was exporting about 700 kilograms of HEU a year to foreign research reactors. Like the United States, the Soviet Union also exported research reactors and the HEU fuel to operate them to other countries. In order to achieve the program’s objective of reducing the use of HEU in civilian research reactors, Argonne is developing new LEU fuels in cooperation with counterparts in other countries, including Argentina, France, and Russia. Developing LEU fuels involves testing fuel samples in research reactors to determine how the fuels behave under normal operating conditions. Fuel manufacturers and reactor operators around the world participate in the program by manufacturing and testing LEU fuels. Owners of foreign research reactors fund conversion of their reactors from HEU to LEU. In 1993, Argonne expanded the reactor conversion program to include cooperation with Russia on the conversion of Russian-supplied research reactors to LEU fuel. The Soviet Union had independently initiated a program in 1978 to reduce the enrichment of HEU fuel in research reactors but suspended the program in 1989 due to lack of funding. Russian-supplied research reactors use fuels manufactured in Russia that are not interchangeable with fuels used by U.S.-supplied research reactors. Therefore, DOE’s reactor conversion program differentiates between U.S.-supplied and Russian-supplied research reactors. Since the reactor conversion program’s inception in 1978, 39 of the 105 research reactors included in the program have either converted or are in the process of converting to LEU fuel. (See app. II for a list of converted research reactors.) Of the remaining 66 research reactors that still use HEU fuel, 35 can convert using currently available LEU fuels but have not done so, and 31 cannot convert to any currently available LEU fuels and still require HEU in order to conduct the research for which they were designed (see fig. 2). A research reactor can begin the conversion process after a suitable LEU fuel is developed and available commercially. The decision to convert from HEU to LEU also depends on research reactor owners having the necessary financial resources, including for the purchase of new fuel. In the United States, NRC regulations require that research reactors under its jurisdiction, including reactors operated by universities, convert to LEU fuel when an LEU fuel that can be used to replace HEU fuel has been developed and when federal funding is made available for the conversion. The conversion process begins with analyses to determine whether the reactor can safely convert and the impact of conversion on the reactor’s performance. After the analyses are completed and regulatory approval for conversion is obtained, the operator can remove the HEU from the reactor and replace it with the new LEU fuel. The HEU fuel can be disposed of once it has been removed from the reactor core and has cooled. According to Argonne’s analysis, conversion to LEU fuel is technically feasible for 35 of the 66 research reactors worldwide that still use HEU fuel. However, only 4 of the reactors—3 foreign reactors that use U.S.- origin HEU and 1 Russian-supplied reactor—currently have plans to convert. Eight U.S. research reactors, including 6 university reactors, could convert to LEU fuel, but according to DOE officials, DOE has not provided the funding to convert them. In addition, DOE has not removed HEU fuel from a university research reactor that has been storing HEU since it converted to LEU in 2000. According to Argonne officials, of the 20 foreign research reactors that currently use U.S.-origin HEU fuel, 14 do not have plans to convert to LEU because they generally have a sufficient supply of HEU and either do not want to incur the additional cost of conversion or do not have the necessary funding. Finally, since DOE’s reactor conversion program initiated cooperation with Russia in 1993, no research reactors that use HEU fuel supplied by Russia have converted. According to Argonne officials, only 1 of 7 Russian-supplied research reactors that could use LEU fuel is scheduled to convert. They said that 5 other Russian- supplied reactors are likely to convert to LEU fuels that are currently available or are expected to become available within the next year. In the United States, there are 6 university research reactors and 2 other research reactors that could convert to LEU fuel but still use HEU fuel. Although DOE has funded the conversion of 11 university research reactors to LEU fuel, the last university reactor converted in 2000. DOE officials said DOE has not provided the funding to convert the 6 remaining U.S. university reactors. DOE recently added 2 other domestic reactors to the reactor conversion program, and neither of these reactors currently has plans to convert to LEU, also because DOE has not provided the necessary funding. (See table 1 for a list of the 8 reactors.) In addition, the university research reactor that converted to LEU in 2000 is still storing HEU fuel because DOE has not removed it. Because the reactor now uses LEU fuel and has no need for HEU, the reactor operator told us that he is eager to return the HEU to DOE for long-term storage and disposal. DOE has a separate program that supports university research reactors, including provision of DOE-owned fuel, and funds their conversion to LEU and removal of spent fuel. According to the DOE official in charge of the university reactor support program, the program has limited funding, and requests for additional funding to support conversion have not been approved by the Office of Management and Budget. Furthermore, the university reactor support program did not receive additional funding to remove HEU fuel from the research reactor that converted to LEU in 2000 until fiscal year 2004, after a group of domestic research reactor operators successfully lobbied Congress to add $2.5 million to the program’s budget to pay for the removal of spent fuel from the reactors. Officials at NRC, which regulates the 6 university reactors, told us that they consider the conversion of the reactors to LEU, the timely removal of HEU fuel after conversion, and the removal of HEU from the reactor that converted to LEU in 2000 as a security enhancement and one of their priorities. NRC officials said that converting the 6 reactors is technically feasible and that the delay in converting the reactors is purely a matter of funding and should be expedited by DOE. However, DOE officials said that DOE had not made the conversion of these reactors a priority. Furthermore, while operators at all 6 universities told us they are willing to convert to LEU fuel, they said it is not a high priority because they do not consider their HEU fuel to be a likely target for theft. For example, one reactor operator explained that the reactor is structured in such a way that the HEU is located inside a concrete enclosure that even experienced reactor staff need almost 2 days to access. These 6 reactors use only a small amount of HEU fuel—less than a kilogram per year, which is not enough to make a nuclear weapon. In contrast, there are other research reactors included in DOE’s reactor conversion program that are larger than the 6 university reactors and use tens of kilograms per year. Nevertheless, operators of the 6 university research reactors said they would convert to LEU when DOE provides funding. Furthermore, the DOE official in charge of the university reactor support program said that converting domestic university reactors is an issue of U.S. nonproliferation policy. He said that converting domestic reactors to LEU would support U.S. efforts to influence foreign reactors to convert to LEU in accordance with the U.S. nonproliferation policy to reduce the use of HEU in civilian research reactors worldwide.