METHOD FOR EXPOSING A MATERIAL BY NEUTRON FLUX TO PRODUCING A USEFUL ISOTOPE AND TO TRANSMUTING AT LEAST ONE LONG-LIVED ISOTOPE OF RADIOACTIVE WASTE

摘要

A material is exposed to a neutron flux by distributing it in a neutron transparent diffusing medium surrounding a neutron source such that neutron scattering within the diffusing medium enhances the neutron flux. Preferably, the diffusing medium has a thickness, between the source and the exposed material, of at least one order of magnitude greater than the diffusion coefficient for elastic neutron scattering within the medium and consists of heavy elements (e.g. lead and/or bismuth) so that multiple elastic neutron collisions slowly decrease the energy of neutrons from the source. Also claimed is production of a useful isotope such as: (i) the radioisotope 128I to be administered to patients and produced by the above method from 127I; (ii) the radioisotope Tc-99m formed by decay of 99Mo produced by the above method from 98Mo; (iii) the radioisotope 131I formed by decay of 131Te produced by the above method from 130Te; (iv) a radioisotope extracted from fission fragments produced by the above method from a fissile element; (v) the radio-isotope 125I formed by decay of 125Xe produced by the above method from 124Xe; and (vi) a doping impurity produced by the above method in a semiconductor material. Further claimed is a process for transmuting one or more long-lived isotopes of a radioactive waste by the above method.