TRANSMUTATION OF NEPTUNIUM, AMERICIUM, TECHNETIUM, AND IODINE IN FASTSPECTRUM CORES DRIVEN BY ACCELERATED PROTONS

A neutronic analysis is presented of three incinerator subcritical lat tices, driven by accelerated protons and designed to transmute the min or actinides, the Tc-99 and the I-129, of light Water reactor (LWR) wa ste. A calculational methodology must first be established to enable a neutronic burnup analysis of fission cores driven by high-energy prot ons. The methodology is based on the following codes: HERMES, the Fors chungszentrum Julich adaptation of HETC, for high-energy interactions; MCNP3, for neutron interactions below 20 MeV of neutron energy; and K ORIGEN, the Forschungszentrum Karlsruhe adaptation of ORIGEN, for burn up analysis. A result of applying the methodology is that the minor ac tinides, the Tc-99, and the I-129, of LWR waste may be transmuted in s ubcritical cores, driven by the spallation neutrons emanating from the bombardment of the cores with 1600-MeV protons. Three core types are required. Core type I is fueled by the minor actinides and is a modifi cation of the Brookhaven National Laboratory PHOENIX. With a proton cu rrent of 20 mA, the core incinerates the minor actinide waste of 14 LW Rs. Core type II contains the Tc-99, I-129, and plutonium waste of 19 LWRs. With a proton beam of 130 mA, the core incinerates the technetiu m and 60% of the iodine. With a fraction of the plutonium coming out o f this core, the remaining 40% of I-129 is incinerated in core type II I. All three cores run to 100 000 MWd/tonne or slightly higher; on the average, no core is a net consumer of grid electricity; all are coole d by sodium but remain subcritical with the loss of coolant.