Mutual shielding effects in the interaction of 238U-235U and 238U-239Pu

Some results concerning mutual shielding calculations are presented. 238U to 235U and 238U to 239Pu interactions were studied for the fissile isotope enrichments between 0 and 4%. The resolved cross sections of fissile isotopes were calculated for 20 and 10000C. The study of the mutual shielding effect, in a heterogeneous cell of volume ratio 2, was performed for three fuel rod radii r = 0,2, 0,5 and 2 cm. A second study of the Doppler effect on the resonance overlap was performed on a homogeneous medium equivalent to the usual P.W.R. lattices. This effect was found to be appreciable. (author)