Calculation of Effective Coefficient of Spontaneity Fission Neutron Source in CFBR-Ⅱ Reactor

In order to calculate the effective intensity of spontaneity fission neutron source in CFBR-II reactor,Monte Carlo calculation method of effective coefficient is built.The naissance and transport process of spontaneity fission neutron and eigen distribution neutron are simulated.The effective coefficient of spontaneity fission neutron source equals to the ratio of leakage neutron number which come from two kinds of neutron sources.Considering the special structure of CFBR-II reactor,for the spontaneity fission neutron sources,the effective coefficient of different positions in upper hemisphere and lower hemisphere are calculated separately using cell-rejection technique.These results can be used as the basis to calculate the total effective intensity of spontaneity fission neutron source.