The epithermal neutron irradiation station for boron neutron capture therapy (BNCT) at the FiR 1 in Otaniemi

The optimal neutron field for BNCT would have only neutrons of the epithermal energy range and would be free of γ-radiation. Such a field penetrates several centimeters into the tissue but does not cause damage so much as higher energy neutrons would. In the depth thermalized neutrons are then captured by the 10B that has accumulated into the tumor. An epithermal neutron irradiation station has been designed and is under construction at the FiR 1 nuclear research reactor in Espoo, Otaniemi. The epithermal field is formed by replacing the graphite in the existing thermal neutron irradiation column with a specially for this purpose developed new composite material, a mixture of aluminum and aluminum fluoride [1]. The performance of the field, as well as the layout of the irradiation station and auxiliary spaces are reported.