THE PRELIMINARY PERFORMANCE ANALYSIS OF THE TRANSMUTATION FUEL FOR HYPER
A U-TRU-(40-60)Zr metallic fuel is being considered as the transmutation fuel for HYPER in Korea. U-TRU-15Zr is also considered as the reference fuel for a critical system. The MACSIS-H for an metallic fuel is being developed as a steady-state performance computer code. The fuel temperature calculation schemes were developed and implemented into the MACSIS-H code to analyze the fuel rod performance. A constituent migration subroutine has been made and installed into the MACSIS-H code to simulate the constituent redistribution. The He production rates calculated by other code were inserted into the swelling/FGR routine of the code. The burnup limits and CDF (cumulative damage fraction) were analyzed by the MACSIS-H code. There are lots of uncertainties in the modelling, so some experimental tests are needed for clarifying the uncertainties of the fuel modeling.
Temperature gradient driven constituent redistribution in UZr alloys
Abstract Although the phenomenon of constituent redistribution is common in UPuZr alloys irradiated under a wide range of conditions, it has been observed in UZr alloys only at elevated temperatures. Redistribution is relatively rapid and is essentially complete by 5 at% burnup. Experimental observations of constituent redistribution in UZr fuel elements are presented and analyzed. A model based on a thermal diffusion mechanism is proposed, and its computer implementation is described. The model calculations, supported by experimental observation, indicate that the excess enthalpy of solution of the bcc γ-phase controls the redistribution process as an additional driving force. A heat of transport of −50 to −100 kJ/mol in this phase results in the best match between calculation and experimental observations. The model predicts that constituent redistribution will be observed only when a region of the fuel operates at temperatures above 935 K.
Thermodynamics of the uranium-zirconium system
Abstract Renewed interest in metallic fuel for nuclear reactors has prompted new studies of the thermodynamics and phase equilibria in binary alloys containing uranium, plutonium, and zirconium so that the ternary phase diagram might be calculated. An analysis of the uranium-zirconium alloy system has been performed. Thermodynamic functions for all existing uranium-zirconium phases have been derived and a phase diagram was calculated. These results are compared with the available thermodynamic data and accepted phase diagrams and general agreement was found. Disagreements generally occurred where experimental data were sparse and when previously drawn phase boundaries were found to be inconsistent with theory.