General Electric's Global Research Center, in New York state, will continue to work over the next 30 months on an effort to make nuclear fuel rods safer and better able to withstand the loss of active cooling, under a $33.7 million research grant from the US Department of Energy (DOE) announced on 25 October. A team from the Global Research Center has been working with the Los Alamos, Oak Ridge and Idaho National Laboratories on IronClad, a material for fuel rods that GE said is more durable in extreme conditions.
Field studies are being carried out by Global Nuclear Fuels (GNF, a GE-led joint venture), Exelon and Southern Nuclear. The new fuel, using the IronClad and ARMOR advanced fuel solutions, will be developed in partnership with the three national laboratories. Evan Dolley, technical operations leader in metals at GE Global Research, said the project aims to develop “alternative fuel rods that are even more resistant and could endure the loss of active cooling in a reactor core much longer than current fuel”. Ceramic matrix composites (CMCs) able to withstand high temperatures would be used in channel boxes surrounding the fuel rods to make the system more resilient, Dolley added.
The project team also is developing additive technologies, which can be used to quickly fabricate 3D metal end caps for prototyping the fuel rod designs. "With the integration of nuclear-grade CMCs, we can exploit the higher heat properties of ceramics to build an even more resilient system. And the use of additive is designed to enable a more rapid response if spare parts are needed for other reactor components," Dolley said.
GNF's IronClad was developed through DOE's Accident Tolerant Fuel Program, launched in 2012 to find new cladding materials and fuel materials that can better tolerate the loss of active cooling in the core while maintaining or improving fuel performance and economics during normal operation. ARMOR coated zirconium cladding provides enhanced protection of fuel rods against debris fretting, and greater resistance to oxidation, than standard zirconium cladding.
Lead test assemblies of GNF accident-tolerant fuel were loaded into unit 1 of Southern Nuclear's Hatch NPP, an 876MWe boiling water reactor earlier in 2018. Two variants of IronClad material - one in a fuel rod form but not containing fuel, the other in the form of a solid bar segment - as well as ARMOR lead test assemblies containing fuel were installed. Further lead test assemblies are planned to be installed at Exelon Generation's Clinton nuclear plant in 2019.