DESIGN OF A HIGH-FLUX EPITHERMAL NEUTRON BEAM USING THE U-235 FISSIONPLATES AT THE BROOKHAVEN MEDICAL-RESEARCH REACTOR

Beams of epithermal neutrons are being used in the development of boro n neutron capture therapy for cancer. This report describes a design s tudy in which U-235 fission plates and moderators are used to produce an epithermal neutron beam with higher intensity and better quality th an the beam currently in use at the Brookhaven Medical Research Reacto r (BMRR). Monte Carlo calculations are used to predict the neutron and gamma fluxes and absorbed doses produced by the proposed design. Neut ron flux measurements at the present epithermal treatment facility (ET F) were made to verify and compare with the computed results where fea sible. The calculations indicate that an epithermal neutron beam produ ced by a fission-plate converter could have an epithermal neutron inte nsity of 1.2X10(10) n/cm(2).s and a fast neutron dose per epithermal n eutron of 2.8X10(-11) cGy.cm(2)/n(epi) plus being forward directed. Th is beam would be built into the beam shutter of the ETF at the BMRR. T he feasibility of remodeling the facility is discussed.