Collective Effect of Finite Fission Chains at Super Prompt Critical

Based on the model of point reactor, a program was constructed to simulate collective effect of finite fission chains and was proved by experimental result. With the program, the evolution of finite fission chains in reactor was researched using macroscopic method. Collective lifetime of chains was calculated and its distribution was deduced. The calculated result demonstrates that the mean of collective lifetime of chains is longer with increasing intensity of neutron source and is shorter with increasing reactivity.