Analysis of a Fast Spectrum Irradiation Facility in the High Flux Isotope Reactor

The Global Nuclear Energy Partnership (GNEP) is proposing to develop a sodium-cooled fast-spectrum reactor (SFR) to transmute and consume actinides from discharged nuclear fuel. To meet performance objectives, new and advanced fuels and targets need to be developed. The fuels to be irradiated include metal and oxide mixed actinides (U-Np-Pu-Am-Cm); for the target concept, Am-Cm has been considered. A significant part of the development process is the irradiation of the fuel and cladding in a prototypic fast reactor environment to determine the performance under irradiation. Analysis results are presented in this paper for a fast-neutron irradiation facility design based on the large fast neutron flux available in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) combined with the use of a strongly-absorbing thermal neutron shield. Several designs were assessed; the preferred concept consists of a three-pin design with an europium oxide thermal neutron shield, to be situated in the HFIR flux trap. Analyses show that this design could provide a fast to thermal neutron flux ratio greater than 400, a fast neutron flux larger than 1 x 10{sup 15} n/cm{sup 2} {center_dot} s, and with an acceptable impact on HFIR operation. This design feasibly will bemore » a relatively low-cost near-term facility that meets the requirements for fast fuel irradiation.« less