Grzegorz Tracz1, Ludwik Dąbkowski2, Dominik Dworak1, Krzysztof Pytel2, Urszula Woźnicka1
1 Department of Environmental and Radiation Transport Physics,
The Henryk Niewodniczański Institute of Nuclear Physics, 152 Radzikowskiego Str., 31-342 Kraków, Poland,
2 Reactor Analysis and Technology Department, Institute of Atomic Energy, 05-400 Otwock-Świerk, Poland
The paper presents results of the numerical modelling of the fission-converter-based epithermal neutron
source designed for a BNCT (Boron Neutron Capture Therapy) facility to be located at the Polish research
nuclear reactor MARIA at Świerk. The unique design of the fission converter has been proposed due to a
specific geometrical surrounding of the reactor. The filter/moderator arrangement has been optimised in
order to moderate fission neutrons to epithermal energies and to get rid of both fast neutrons and photons
from the therapeutic beam. The selected filter/moderator set-up ensures both the high epithermal neutron
flux and the suitably low level of beam contamination. The elimination of photons originated
in the reactor core is an exceptional advantage of the proposed design. It brings one order of magnitude
lower gamma radiation dose than the permissible dose in such a type of therapeutic facility is required.
The MCNP and FLUKA codes have been used for the computations.