Proposal for no-cost extension and re-scope for UNLV TRP Project: Neutron Multiplicity Measurements for the AFCI Program (Advanced Fuel Cycle Initiative)

The U.S. Advanced Fuel Cycle Initiative (AFCI) is a program to develop economic and environmental methods to reduce the impact of waste from commercial nuclear fuel cycles. One concept for near-complete destruction of waste isotopes from used nuclear fuel is accelerator-driven transmutation. High-power accelerators would be used to produce high-energy charged particles, which then collide with heavy metal targets to create a cascade of neutrons. These neutrons then cause a nuclear chain reaction in subcritical systems. Fission neutrons then transmute fissile waste isotopes as well as other problematic isotopes such as technetium-99 and iodine-129. To design these systems, complex reactor physics computer codes and highly detailed data libraries are used to compute the reactivity of systems, reaction rates, destruction rates, and nuclear-induced damage rates to materials. In this project, we will use a Russian-built detector system to make measurements of neutrons generated in a central target by a variety of accelerators. We will also use the most advanced high-energy radiation transport code, MCNPX, to model the experiments. Experimental results will be compared to computational predictions and discrepancies will be investigated. We will conduct experiments using a 70-MeV proton cyclotron at the Crocker Nuclear Laboratory at the University of California at Davis. We will also make measurements with a 20 to 40 MeV electron linac (linear accelerator) at the Idaho Accelerator Center at Idaho State University. Finally, we will use the 800-MeV linac at the Los Alamos Neutron Science Center at Los Alamos National Laboratory