BNCT-project at the Finnish Triga reactor

An epithermal neutron irradiation station for the Boron Neutron Capture Therapy (BNCT) will be constructed in the thermal column of the Finnish Triga reactor. The first target of the BNCT at FiR 1 is the treatment of malignant brain tumors. The epithermal neutrons have the capability to penetrate deep into the brain tissue thermalizing at the same time. The thermal neutrons are captured by 10B-nuclei situated ideally in the tumor cells only and thus the reaction products destroy selectively only the tumor cells. The graphite filling of the thermal column will be replaced by a special moderator material: Al+AlF3. The moderator material and its thickness has been chosen so that the system produces as much as possible epithermal neutrons with low fast neutron and gamma contamination. Both fast neutrons and gamma radiation are harmful for the patient. To reduce the gamma radiation there is a lead-bismuth gamma shield at the outer end of the moderator block. In spite of the low power (250 kW) of the reactor the needed epithermal neutron dose to destroy the tumor will be accumulated in a reasonable time e.g. 0.5 to 1.5 h. This is possible because of the rather short distance between the reactor core and the irradiation target.