CALCULATIONS OF THE DOPPLER COEFFICIENT OF LARGE CERAMIC-FUELED FAST REACTORS

ABS>Calculations of the Doppler coefficient of large, ceramicfueled fast reactors containing plutonium were made by means of the ELMOE program to provide accurate flux calculations. The temperature-dependent cross sections of P. Greebler et al., for U/sup 238/ and Pu/sup 239/ were used. Doppler coefficients of the order of 10/sup -5/ ntermediate tem k/ C were obtained, in agreement with Greebler's results. Coefficients of carbide fueled reactors are about 0.7 of those of oxide-fueled reactors at the same fuel enrichment. Effective coarse- group elastic-removal cross sections for light elements are tabulated. It appears that, with tabulations of this sort as a guide, coarse-group sets of cross sections can be constructed to give adequate accuracy in calculations of Doppler coefficients without use of ELMOE. (auth