Breached oxide blanket fuel behavior in an LMR

The run-beyond-cladding-breach (RBCB) behavior of fertile uranium dioxide fuel poses the same questions as that of exposed driver fuel to liquid-metal reactor (LMR) operations and maintenance. If sodium reacts with the blanket fuel, the product may be sufficient to induce cladding loading. This loading, then, has the potential to extend and/or induce cladding failures and degrade overall rod integrity. These open breaches expose fuel or reaction product to sodium and release fission gas, and delayed neutrons, and, potentially, fuel to the primary coolant. These phenomena are being studied as part of a joint program in Experimental Breeder Reactor II (EBR-II) between the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan. Operation of this breached blanket pin caused no operational problems at EBR-II, and the overall consequences of RBCB operation of blanket fuel appears to be benign