High Performance Coatings for Spent Fuel Containers and Components

It has been found that the corrosion resistance of Fe-based amorphous-metal alloys can be improved dramatically through additions of chromium, molybdenum, and tungsten. The addition of yttrium lowers the critical cooling rate of these materials, but complicates the gas atomization process. High concentrations of boron enable these alloys to serve as effective neutron absorbers for criticality control applications. Since these alloys are Fe-based, any substitution of these for Ni-based alloys in the storage of spent nuclear fuel (SNF) applications could result in significant cost savings. Large quantities of amorphous alloy powders have now been successfully produced in multi-ton quantities with gas atomization, and applied to several half-scale SNF containers and criticality control (basket) structures with the high-velocity oxy-fuel (HVOF) thermal spray process. Corrosion rates determined with linear polarization in a variety of repository-relevant brines, and the results of recent salt fog testing of large-scale prototypes are presented.