Streszczenie:
The paper presents the third step of the numerical modeling of the fission-converter-based epi-thermal neutron source designed for the Polish Boron Neutron Capture Therapy (BNCT) facility to be located at the Polish research nuclear reactor MARIA at Świerk. The optimization of the fission con-verter has been carried out again. The epithermal neutron flux has increased 240 % comparing with the variant proposed previously while the number of fuel rods was significantly reduced. The specific photon and fast neutron doses meet the requirements of the therapy. Optimization of the reflector sur-rounding the filter/moderator as well as collimator shape, length and liner has been also carried out. Configuration of the filter/moderator has remained the same. Criticality calculations show that keff of the fission converter filled with light water is below 1. The MCNP code has been used during compu-tations.
