CONCEPTUAL DESIGNS OF EPITHERMAL NEUTRON BEAMS FOR BORON NEUTRON-CAPTURE THERAPY FROM LOW-POWER REACTORS

Convenient, economical epithermal neutron beams will be needed in the future for boron neutron capture therapy (BNCT). We studied two concep ts for producing epithermal neutron beams with low-power reactors. The first design is a 100-kW reactor with a U-235 fission plate placed ou tside the reflector region, plus an Al/Al2O3 moderator assembly. The b eam, which is directed forward, delivers a flux of epithermal neutrons of 0.8 x 10(9) n/cm2.s and a fast neutron dose of 4.4 x 10(-11) cGy.c m2/n(epi). The second design is based on a slab reactor plus a similar Al/Al2O3 moderator assembly. With an operating power of 50 kW, the be am has an intensity of 1.4 x 10(9) n/cm2.s and a fast neutron dose of 4.6 x 10(-11) cGy.cm2/n(epi); this beam also is directed forward. Thes e epithermal neutron beams should be acceptable for BNCT; a treatment could be completed in approximately 1 h, and the fast neutron dose to the skin would not be the limiting dose. Such small reactors should be practicable in a hospital location.