Three-dimensional thermal aspects of aluminum fuel elements

Research reactors are unique in that their mission is to be a source of neutrons for use in the irradiation of test materials, production of isotopes, or as beams for theoretical physics research. To maximize the available neutrons and the flux levels outside of the fuel zone, these reactors utilize aluminum clad, uranium alloys. The fuel elements are generally plate type with small coolant channels. This results in an undermoderated core, with flux peaks at the fuel edge and resultant higher heat fluxes. If operating and safety margins are evaluated with one- or two-dimensional heat transfer codes, the allowable operating power is restricted or hard-to-justify assumptions have to be made as to what is a smeared representative heat generation rate. A computer program was written that interfaced with the thermal analyzer MITAS. It has been revised to interface with the thermal analyzer SINDA.