Doppler effect experiment of resonance materials for rock like oxide fuels

A Doppler effect experiment of resonance materials such as erbium, tungsten , thorium and uranium was carried out in the Fast Critical Assembly of Japa n Atomic Energy Research Institute. Cylindrical shaped samples of 150 mm in stack length and 23 mm in diameter were fabricated. The sample was contain ed in capsules and placed at the center of the core. Temperature of the sam ple was raised up to 1073 K. Measured Doppler reactivities of erbium, thori um and tungsten are comparable with those of uranium. Analysis was performe d using the SRAC code system. Effective absorption cross sections of the sa mples were generated by two different methods. One is the f-table method ba sed on the NR approximation and the other is the PEACO method that performs direct calculations of resonance absorption with an ultra fine energy grou p structure. Calculated results were compared with the measured values. For all samples except the tungsten, the f-Table method gives 1 similar to7 % smaller reactivity than the PEACO method. Both methods predict the measurem ents within the error of 6 %. For the tungsten sample, the calculations und erestimate the measurement by about 10 %. (C) 2001 Published by Elsevier Sc ience Ltd. All rights reserved.