Crystal Binding Effect of UO₂ on the Effective Resonance Integral

抄録

Crystal binding effect on the effective resonance integral of UO₂ fuel has been evaluated with a simplified phonon frequency distribution. Gaussian frequency distribution having one fitting parameter was adopted. With this distribution the line shape of the resonance cross section was expressed by a superposition of the ψ-functions, which lead to a rather simple calculation of the resonance integral. The calculated results on UO₂ crystal showed about 1% increase in the effective resonance integral at room temperature. Although this effect decreased at an elevated temperature, it conversely makes 5 to 10% decrease in Doppler coefficient com-pared with the free gas treatment.