Neutronic characteristics systems of SAMOP (Subcrtical Assembly for Mo-99 Production)

SAMOP (Sub-critical Assembly for Mo-99 Production) is a system of sub-critical solution which is aimed at producing isotope Mo-99 through a process of fission reaction. In order to sustain the fission process of the sub-critical system, additional neutron source is incorporated which comes from one of the Kartini reactor beam ports. The system shall ensure the sub-critical state at any condition with adequate margin. Any conditions or events that could lead to reactivity change have to be identified, such as change in fuel solution concentration, either due to leakage, evaporation or heating process. System code of MCNP and MVP were used to analyze the neutronic characteristics of SAMOP. The analysis was intended to determine the neutronic characteristics of SAMOP system, such as under moderated range, uranium concentration and the allowable number of solution tubes or TRIGA fuels inserted into peripheral holes to keep the core subcritical at any condition. From the calculations, the preferable nominal uranium density is 300 gU/l. (author)