Process flow simulation for the fabrication of commercial nuclear fuel assembly subcomponents

Framatome ANP (FANP) recently merged with Siemens Power Corporation to form one of the world´s largest suppliers of fuel assemblies for commercial nuclear power plants. This merger offers the potential for cost reductions and logistical improvements through the integration of FANP´s two North American fuel fabrication facilities. According to plan, the current production uranium fuel rods and assemblies at Lynchburg, VA, will move to the Richland, WA, and the current production of spacer grids at Richland will move to Lynchburg. As a result, the number of different grids and the overall throughput of all grids at Lynchburg will double. We describe a simulation study commissioned by FANP to determine the impact of the consolidation at Lynchburg. Discrete-event simulation was applied first to study the existing grid fabrication process. A baseline model was developed that captures current process flows. This stochastic model was calibrated using data collected on the production floor, verified using deterministic line-of-balance calculations, and validated against historical throughput data. The baseline model was then extended to incorporate the new facility layout, equipment additions, and anticipated load. The enhanced model was used to predict potential bottlenecks and to refine resource and process modifications needed to manage the additional load effectively within the fabrication schedule constraints. To provide a tool for continuing operations management, use cases were developed and spreadsheet interfaces were implemented which allow FANP engineers to explore evolving operational scenarios.