Development of a Fuel Bundle with 43 Elements Containing Mixed Oxide of Thorium and Uranium (T43) In ICN. A Summary Report of Research Contract with Institute for Nuclear Reactor (INR), Romania. Annex V

Thorium represents a valuable fuel alternative to uranium, but since it has no fissile isotopes, it is necessary to foresee using a small amount of fissile material to initiate the chain reaction. Many studies (related to reactor physics and fuel performance) have been performed worldwide for Th+U, Th+Pu and even Th+Minor Actinides. In Romania, given the safeguard limitations, the only considered fissile material is U-235. The thorium fuel cycles in CANDU nuclear reactors maintain their strategic interest as they ensure a long-term resources availability, especially for those countries possessing large thorium reserves but limited uranium resources. Again, driven by safeguard limitations, the 'once-through' thorium cycle without reprocessing was taken into account. This report reviews the analytical and experimental work performed at Institute of Nuclear Reactor (INR) concerning the nuclear fuel containing mixed oxide of thorium and uranium to be used in existing CANDU reactors. A major request was that the CANDU power plant design, especially the reactor core design, should not be modified in order to comply with using the advanced fuel bundles, excepting for the fuel bundle itself. Based on previous studies performed in Canada, China, India and Korea, the fuel bundle considered for hosting mixed oxide of thorium and uranium would be T43, a 43 elements bundle.