Hot-pressing study on mixed uranium--plutonium nitride for advanced reactor fuel

The hot-pressing characteristics of mixed (U,Pu)N for advanced reactor fuel were studied in order to provide a better insight into the densification process and thus improve fuel fabrication technique. A detailed experimental procedure for continuous measurement of densification and an analog computer circuit to simulate hot-pressing are presented. Mixed (U,Pu)N of 99 percent density was fabricated at 4000 psi and 1450$sup 0$C, and 94 percent density was obtained with 3000 psi at 1450$sup 0$C. A digital computer program for the densification process was also written to analyze and predict the density of the pellet at any given time or at different applied pressures than those actually tested. The time dependence of the temperature in the proposed equation to simulate the experimental heating period of the die was first introduced to improve the interpretation of experimental data. The best values of the hot- pressing coefficients were determined by curve fiting of the equation with experimental data. The values are given for mixed (U, Pu)N that had been fabricated with a starting density of 63 percent and a hot-pressing pressure of 3000 psi at 1450 +- 10$sup 0$C. (auth