Study of Heterogeneity Effects on the Sodium Void Coefficients

Kobayashi, Takatoshi*; Sugawara, Akira*; Seki, Yuji*; Ikezawa, Hiroko*

As a continuation of the previous research, heterogeneity effects ofneutron spectra and axial leakage have been examined.Spectra in a two-region cell were computed by a collision probabilitymethed and the heterogeneity effect was found to be small.The analysis of the axial leakage was carried out with the Benoist'sdirectional collision probability method and it turned out that theheterogeneity has negative contribution to the sodium void coefficient. Combining the results of the previous research and the current one,the heterogeneous void coefficient in a prototype fast reactor moves towardsthe positive direction from the homegeneous result.