Microstructure and corrosion performance of a neutron absorbing Ni-Cr-Mo-Gd alloy

The National Spent Nuclear Fuel Program (NSNFP), located at the Idaho National Engineering and Environmental Laboratory (INEEL), coordinates and integrates national efforts in management and disposal of U.S. Department of Energy (DOE)-owned spent nuclear fuel (SNF). These management functions include using the DOE standardized canister for packaging, storage, treatment, transport, and long-term disposal. Nuclear criticality control measures are needed in these canisters because of the enrichment and total quantity of fissile material in some types of the DOE SNF. This paper will describe the NSNFP's metallurgical development program of Nickel-Chromium- Molybdenum-Gadolinium alloys that are being developed for nuclear criticality control in the DOE standardized canister. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross-section. The microstructure, mechanical properties, and corrosion resistance of various alloys will be presented. These corrosion resistant, structural alloys can be used to fabricate components of SNF storage racks, storage canisters and internal structural baskets, and transportation cask internals. The focus of this work is to qualify these materials for ASME code qualification and acceptance in the Yucca Mountain Repository.