Nuclear Reactors 275 - Korea Atomic Energy Research Institute Developes New Uranium Molybdenum Fuel For Test Reactors
The Korea Atomic Energy Research Institute (KAERI) in Daejeon, South Korea was established in 1959. It is the only professional research-oriented institute for nuclear power in South Korea, In 1995 KAERI designed and constructed the nation's first multipurpose research reactor, HANARO based on the Canadian MAPLE design. Among other tasks, KAERI works on the development of advanced nuclear fuels.
Conventional nuclear fuel is made from uranium. Uranium-235 is enriched from its natural concentration of about .71 percent of uranium ore to 3.5 to 4.5 percent. It is processed into uranium dioxide and then fired in an oven to create a hard ceramic. The ceramic is ground into powder and made into pellets of uniform size which are then inserted into tubes. The tubes are bundled into assemblies to insert into the reactor core.
Test reactors have utilized a wide variety of fuels with a large range of enrichments. Early test reactors used fuels enriched to more than seventy percent U-235. Concerns over the proliferation of nuclear weapons led to a movement to reduce the level of enrichment used in test reactors. It was concluded that twenty percent enrichment was sufficient for test purposes and was low enough to substantially reduce the risk of the proliferation of nuclear weapons. Most test reactors underwent core conversion to use fuels that were enriched less than twenty percent under the Reduced Enrichment for Research and Test Reactor (RERTR) program developed by the U.S. Department of Energy.
The U.S. Argonne National Laboratory held a workshop to discuss the requirements for the qualification of U-Mo alloy fuel for use in test reactors on January 17-18, 2000. Thirty-one participants representing 21 reactors, fuel developers, fuel fabricators, and fuel reprocessors in 11 countries took part in the workshop. The participants agreed that the qualification plans of the U.S. RERTR program and the French U-Mo fuel development program were valid.
KAERI has created an alloy of uranium and molybdenum that has twice the density of uranium per unit volume as conventional uranium dioxide ceramic pellets. Tests were conducted with a molybdenum content between four percent and seven percent. It was found that a molybdenum content of at least six percent yielded a fuel with the desired characteristics. This new alloy provides for higher output and improved combustion. This means that the same amount of uranium provides more power than conventional fuels. Reactors can burn the new U-Mo fuel for fifty percent longer than the U-O fuel before needing to be refueled.
Samples of the new fuel have been sent to the Idaho National Laboratory for testing in their ATR research reactor. The fuel tests will continue until the end of 2017. If all goes well, the next phase will consist of the new fuel being tested Korea’s new research reactor under construction in Busan City. If all the tests return the expected results, Korea intends to manufacture and export the new U-Mo fuel.
