Optimization of the neutronics design of MNSRs

The small daily operation time of MNSRs and the consequent limited use of these reactors imply that their neutronics design should be improved.The optimization of the neutronics design is based on the optimization of all the neutronically influential components, the latest of which are the regulators. Both cadmium and stainless steel absorbers are substituted by boron. About 3.0 mm thickness of the Top Beryllium Reflector Shims are added to compensate for about 1 mk loss of initial excess reactivity caused by the now more efficient regulators.The new initial excess reactivity is about 4 mk. The daily operable time is extended to about 28.00 hrs, and much more samples (about ten times) can be irradiated daily. The neutronic characteristics of the optimized reactor are compared with those of the actual reactor. Advantages are listed, and savings are estimated.