Monte-Carlo calculations for the development of a BNCT neutron source at the Kyiv Research Reactor.

Abstract The results presented in this paper display our continuing steps toward development of a neutron source with parameters required by boron neutron capture therapy (BNCT) at the Kyiv Research Reactor (KRR). The purpose of this work was: (1) calculation of the neutron flux which can be achieved at the greatest possible approach of a patient to the reactor core; (2) analysis of the influence of a nickel collimator and a nickel-60 filter on the characteristics of the neutron beam; (3) creation and validation of the MCNP calculational pattern for an actual core fuel load in the KRR. Results of calculations were carried out by means of the MCNP4C code included: (1) An epithermal neutron flux of 3×10 9 –5×10 9  neutron/cm 2  s with an epithermal-to-fast flux ratio of 80–230 could be obtained at the KRR, using a natural nickel layer on the interior borated polyethylene collimator wall and a 60 Ni filter. (2) Use of the 60 Ni filter may be useful to increase the ratio epithermal-to-fast flux without a substantial decrease in the magnitude of the epithermal neutron flux. (3) The MCNP model proposed in this paper could also be useful for reactor safety calculations.