Calculation of Fission Rate in CFBR-Ⅱ Reactor

In order to study the fission rate distribution in CFBR-II reactor,the calculation method of fis-sion rate based on MCNP is built and checking computations are conducted using the high enriched bare ura-nium sphere in foreign countries.The fission rate distribution in the top and bottom hemispheres in CFBR-Ⅱ reactor is calculated along virtual path setting at the direction of 45o.The results indicate that the maximum fission rate lies in neither the system center nor the hemisphere center but some place in the enriched uranium core.The total fission rate of center normalization in the reactor is calculated to be 3 150.3 by distribution integral method,in which the contribution of deficient uranium reflector is 5%.