About possibilities of efficient multiplication factor calculation of the fast-thermal critical assembly

Characteristics of fast-thermal systems (availability of fast and thermal reactors in one assembley ) offer additional difficulties for their calculation. Existing mathematical programs of DRZM or KRAB-1 type are intended for calculation of fast and intermediate reactors and don't allow characteristics of fast-thermal systems to be described correctly. For this reason calculation accuracy of efficient multiplication factor of the fast-thermal critical assembley BTS-4, simulating material composition and neutron spectrum of designed mean power fast reactor, is unsuffucient. The effects of heterogeneity and thermalization of the assembley thermal zone with the help of DRZM or KRAB-1 special mathematical programs are considered, and obtained macrosections are proposed to be introduced into DRZM or KRAB-1 mathematical programs. The results of calculation show, that this approach allows the error of the determination method of the efficient multiplication factor of the BTS-4 model fast-thermal critical assembley to be lessened essentially and can be used for calculation of Ksub(eff) of other fast-thermal systems