Monte Carlo Simulations of Models for Accelerator Transmutation of Waste

The Los Alamos Accelerator Transmutation of Waste (ATW) program is directed toward the dual goals of alleviating the problems associated with existing high-level radioactive defense wastes, and of developing systems for the generation of fission energy with minimal production of high-level, long-lived nuclear wastes. In the Los Alamos ATW concept, a high-current, high-energy proton accelerator creates and intense flux of neutrons through spallation in heavy metal targets. The high neutron flux levels available in such systems allow the rapid burning even of nuclides with small cross sections, the design of systems with dilute inventories, and the operation of systems far from criticality. A crucial tool for ATW simulations is the LAHET Code System (LCS), which consists of the Los Alamos version of the HETC Monte Carlo code, a special version of the MCNP code, and several tallying and postprocessing utilities. Here we present results for a baseline system designed to transmute technetium. 16 refs.