CHARACTERIZATION OF AN ADVANCED GADOLINIUM NEUTRON ABSORBER ALLOY BY MEANS OF NEUTRON TRANSMISSION

Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the alloy at specific gadolinium dopant levels. The new alloy is to be deployed for criticality control of highly enriched DOE SNF. For the transmission experiments, alloy test samples were fabricated with 0.0, 1.58 and 2.1 wt% natural gadolinium dispersed in a Ni-Cr-Mo base alloy. The transmission experiments were successfully carried out at the Los Alamos Neutron Science Center (LANSCE). Measured data from the neutron transmission experiments were compared to calculated results derived from a simple exponential transmission formula using only radiative capture cross sections. Excellent agreement between the measured and calculated results demonstrated the expected strong thermal absorption capability of the gadolinium poison and in addition, verified the measured elemental composition of the alloy test samples. The good agreement also indirectly confirmed that the gadolinium was dispersed fairly uniformly in the alloy and the ENDF VII radiative capture cross section data were accurate

NSNFP Activities in Support of Repository Licensing for Disposal of DOE SNF

The U.S. Department of Energy (DOE) Office of Civilian Radioactive Waste Management is in the process of preparing the Yucca Mountain license application for submission to the Nuclear Regulatory Commission as the nation’s first geologic repository for spent nuclear fuel (SNF) and high-level waste. Because the DOE SNF will be part of the license application, there are various components of the license application that will require information relative to the DOE SNF. The National Spent Nuclear Fuel Program (NSNFP) is the organization that directs the research, development, and testing of treatment, shipment, and disposal technologies for all DOE SNF. This report documents the work activities conducted by the NSNFP and discusses the relationship between these NSNFP technical activities and the license application. A number of the NSNFP activities were performed to provide risk insights and understanding of DOE SNF disposal as well as to prepare for anticipated questions from the regulatory agency