Optimization of High Burnup Light Water Reactor Cores within Fuel Performance Limits

High burnup fuel for the current and future operating fleet of light water reactors has the potential to increase reactor performance while decreasing the production cost of electricity. Advanced claddings and fuel forms are being developed to achieve fuel burnup that exceeds the current fuel rod burnup limit. There is a significant economic benefit that can be derived from the use of high burnup fuel. For example, increasing the average fuel discharge burnup by 50% is equivalent to increasing the energy produced by 50% or decreasing the uranium fuel loading by 33% compared to existing fuel products. High burnup fuel can increase energy production for the same uranium loading, thus enabling power uprates or longer fuel cycles. Power uprates increase capacity factor by allowing a plant to generate more electricity over the same operational period. Longer fuel cycles reduce the number of refueling outages and outage days over the plantĺs lifetime, thus increasing plant availability. Fuel cost savings through higher discharge burnup can be realized through reduced uranium requirements and lower costs associated with reduced nuclear waste. To realize the benefits of high burnup fuel, design margins critical to safety and operations must be addressed as part of the fuel and core design. Specifically, constraints on fuel fragmentation, relocation, and dispersal during loss of coolant accidents must be addressed within the framework of multicycle fuel management. A software product solution is proposed based on developing a novel, automated process for large-scale optimization to determine high burnup core designs over a multicycle planning horizon that incorporates the prior fuel operating behavior. The approach redefines and encodes a new core design process whereby traditional single-cycle design is replaced by multicycle design optimization incorporating detailed fuel operating history. This will be important for selecting carryover fuel between refueling cycles and placing fresh reload fuel within the core loading pattern. Incorporating fuel performance as a set of formal constraints into the fuel and core design process will be the key to maximizing the economic benefit of high burnup fuel. In phase 1 of this proposal, a multicycle optimization capability will be developed to incorporate fuel performance constraints for high burnup fuel into the core design process. The optimization will be demonstrated for an anticipated 24-month design with a power uprate to illustrate the inclusion of high burnup fuel into the core design while maintaining all design constraints. Phase 2 will focus on integrating a higher fidelity core simulation capability into multicycle optimization using a multi-scale approach to ensure accurate predictions of all design constraints. The optimization capability would be demonstrated by working closely with an industry partner to benchmark the reactor model using historical data and establish a high burnup fuel transition strategy.