Design of Neutron Beams for Boron Neutron Capture Therapy in a Fast Reactor

The BNCT (Boron Neutron Capture Therapy) technique makes use of thermal or epithermal neutrons to irradiate tumors previously loaded with 10B.A thermal neutron beam can be very effective for the treatment of surface tumors such as skin melanoma, but it cannot be used for the treatment of deep pathologies, due to its limited penetration depth. Neutron sources providing an epithermal spectrum of energy ranging from 0.4 eV to 10 keV are being considered for clinical use for the treatment of deep-seated tumors.Reactors are currently seen as a suitable neutron source for BNCT implementation, due to the high intensity of the flux they can provide.The Tapiro reactor, that is located at the ENEA Casaccia Center near Rome, is a low-power fast-flux research reactor that can be useful employed for this application. It is a highly enriched uranium-235 fast neutron facility with a nominal power of 5 kW.In this work computer simulations and experimental arrangements were carried out for this reactor to obtain epithermal and thermal neutron beams for the application of BNCT in Italy in the framework of a specific research program.Using the MCNP-4B code, Monte Carlo calculations were carried out to determine the materials suitable for the design of the thermal and epithermal columns. Various arrangements of reflector and moderator materials have been investigated to achieve the desired experimental conditions.