## Coupled Monte Carlo Neutronics and Fluid Flow Simulation of Small Modular Reactors

The objective iof this project is to provide benchmarks for multicycle operational design parameters for small modular reactors by 2025. At the end of this four-year effort, we will have (i) produced full-core benchmark data beyond startup and (ii) advanced the simulation capabilities to enable multicycle operational modeling in time for delivery of the exascale platform. The challenge is to use the next-generation exascale computing platforms to enable high resolution, operational reactor modeling that extends beyond beginning of life.

Our approach is to integrate Monte Carlo neutronics and computational fluid dynamics—the most accurate numerical methods available for operational reactor modeling—for efficient execution on exascale systems. We are building on a base of applications that have demonstrated high efficiency and excellent scaling on current, petascale leadership-computing levels. We anticipate that 70% of our development effort will focus on optimization of algorithms for exascale performance, with a remaining 30% on numerics and model development to efficiently enable the fully coupled physics.