Trade-off between neutron excess and long-term toxicity reduction by employing LLFP incineration

The effect of incineration of long life fission products (LLFPs) on the reduction of long-term toxicity and decrement of neutron economy is studied for a sodium cooled fast reactor in the nuclear equilibrium state. Either isotope separation or element separation is considered for each LLFP incineration. All LLFPs can be incinerated, if isotope separation is employed for every nuclide except 99Tc with discharge constant of 1/2 year-I for other fission products. However it becomes difficult, if the separation is changed from isotopic to elementary. Some calculated results for typical cases are presented