Reactivity feedback coefficients of a material test research reactor fueled with high-density U 3Si 2 dispersion fuels

Abstract

The reactivity feedback coefficients of a material test research reactor fueled with high-density U 3Si 2 dispersion fuels were calculated. For this purpose, the low-density LEU fuel of an MTR was replaced with high-density U 3Si 2 LEU fuels currently being developed under the RERTR program. Calculations were carried out to find the fuel temperature reactivity coefficient, moderator temperature reactivity coefficient and moderator density reactivity coefficient. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It is observed that the average values of fuel temperature reactivity feedback coefficient, moderator temperature reactivity coefficient and moderator density reactivity coefficient from 20 °C to 100 °C, at the beginning of life, followed the relationships (in units of Δ k/ k × 10 −5 K −1) −2.116 − 0.118 ρ U, 0.713 − 37.309/ ρ U and −12.765 − 34.309/ ρ U, respectively for 4.0 ≤ ρ U (g/cm 3) ≤ 6.0.