Doppler effect experiment of resonance materials for rock like oxide fuels

Abstract

A Doppler effect experiment of resonance materials such as erbium, tungsten, thorium and uranium was carried out in the Fast Critical Assembly of Japan Atomic Energy Research Institute. Cylindrical shaped samples of 150 mm in stack length and 23 mm in diameter were fabricated. The sample was contained in capsules and placed at the center of the core. Temperature of the sample was raised up to 1073 K. Measured Doppler reactivities of erbium, thorium and tungsten are comparable with those of uranium. Analysis was performed using the SRAC code system. Effective absorption cross sections of the samples were generated by two different methods. One is the f-table method based on the NR approximation and the other is the PEACO method that performs direct calculations of resonance absorption with an ultra fine energy group structure. Calculated results were compared with the measured values. For all samples except the tungsten, the f-Table method gives 1∼7 % smaller reactivity than the PEACO method. Both methods predict the measurements within the error of 6 %. For the tungsten sample, the calculations underestimate the measurement by about 10 %.