Powder Injection Overmolding of High Burnup Light Water Reactor Fuels

Globally, the majority of nuclear reactors in operation are light water reactor (LWR) designs and are expected to remain a steadfast low-energy carbon sources for the foreseeable. LWR technology would greatly benefit from fuel materials that can withstand increased burnup, however. By creating a fuel with higher burnup capability, fuels can remain in the reactor longer, leading to less refueling outages and lower waste streams. A radial functionally graded material (FGM) structure within ceramic LWR fuel pellets could improve performance at high burnup but economically viable manufacturing solutions are currently lacking. Powder injection molding (PIM) processes are a promising approach to creating FGM LWR fuels on a scale that is comparable to press-and-sinter. Using PIM, an overmolding technique can be devised, enabling radial compositional gradient of various fuel materials such as fissile, fertile, intert, absorbing, moderating, or thermal enhancing content. This results in several possible advantages, including LWR fuels that result in enhanced power profiles across both pellet and core. Localized high burnup structure (HBS) at the pellet rim, which can lead to fission gas release (FGR) under transient scenarios, can be delayed. Combined with an FGM structure that enhances fuel utilization through burnup, a safer, longer lasting LWR fuel can be made. JFoster & Associates, LLC (JFA) proposes the development of Geometrically Optimized Burn Structures fOr Power Profile Enhancing Reactors (GOBSTOPPER) using a novel PIM overmolding approach. JFA will develop initial manufacturing processes that focus on optimization of resin rheology through variance of process and material parameters. This initial manufacturability study will be performed alongside a modeling and simulation component in an effort to design and begin process optimization for follow-on irradiation studies. The manufacturing component will consist of a surrogate study in the first of half of Phase I which sets the stage for work towards optimization of UO2-bearing GOBSTOPPER designs planned for the second half of Phase I. The high burnup capability of GOBSTOPPER has a positive impact on fuel cycle economics. This improves the sustainability of LWR technology, thus helping secure its viability as a low-carbon, base-load energy source for many years to come. Additional to licensing of fuel technologies, JFA plans to use its manufacturing infrastructure to accelerate new fuels R&D through both proprietary and collaborative efforts. JFA anticipates this will allow new technologies to be tested and reach technical readiness on a reduced timeline.