A design for a slab reactor to produce an epithermal neutron beam and a thermal neutron beam for use in neutron capture therapy (NCT) is described. A thin reactor with two large-area faces, a ''slab'' reactor, was planned using eighty-six 20 enriched TRIGA fuel elements (General Atomics, San Diego, California) and four B4C control rods. Two neutron beams were designed: an epithermal neutron beam from one face and a thermal neutron beam from the other. The planned facility, based on this slab-reactor core with a maximum operating power of 300 kW, will provide an epithermal neutron beam of 1.8 x 10(9) n(epi)/cm2.s intensity with low contamination by fast neutrons (2.6 x 10(-13) Gy.cm2/n(epi)) and gamma rays (<1.0 x 10(-13) Gy.cm2/n(epi)) and a thermal neutron beam of 9.0 x 10(9) n(th)/cm2.s intensity with low fast-neutron dose (1.0 x 10(-13) Gy.cm2/n(th)) and gamma dose (<1.0 x 10(-13) Gy.cm2/n(th)). Both neutron beams will be forward directed. Each beam can be turned on and off independently through its individual shutter. A complete NCT treatment using the designed epithermal or thermal neutron beam would take 30 or 20 min, respectively, under the condition of assuming 10 mug B-10/g in the blood. Such exposure times should be sufficiently short to maintain near-optimal target (e.g., B-10, Gd-157, and U-235) distribution in tumor versus normal tissues throughout the irradiation. With a low operating power of 300 kW, the heat generated in the core can be removed by natural convection through a pool of light water. The proposed design in this study could be constructed for a dedicated clinical NCT facility that would operate very safely. References: 20
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