Doppler effect measurement on resonance materials for rock-like oxide fuels in an intermediate neutron spectrum

Doppler effect experiments on resonance materials for rock-like oxide (ROX) fuels were carried out to examine the calculation accuracy in the intermediate neutron spectrum of the Fast Critical Assembly (FCA) of the Japan Atomic Energy Research Institute. This study is the second phase of a series of Doppler effect experiments on the resonance materials, which follows the measurements in the fast neutron spectrum. The Doppler effect was measured as the sample reactivity change between the heated and unheated samples. Cylindrical samples of resonance materials such as erbium metal (Er), tungsten metal (W) and thorium dioxide (ThO2) were used. The sample was heated up to 1073 K at the center of the FCA core. The experiments were analyzed by the SRAC code system with the use of the JENDL-3.2 cross-section library. The calculated Doppler effects of the W and ThO2 samples agreed with the measured values within the experimental error, while the calculation overestimated the measured Doppler effect of the Er sample by 12%.