Current Status and Future Directions of Neutronics Methods for Reactor Core Simulation

In summary, current methods lack the desired accuracy and fidelity for core simulation in advanced and Generation IV reactors. As a result, it is desirable to develop a method that is either solely based on transport theory or both transport and diffusion but with additional research to eliminate the shortcomings of current decoupled methods if possible. An example of transport/diffusion approach might be a Monte Carlo normalized diffusion theory at the whole core level. In either case (pure transport or transport/modified-diffusion), significant new research will be needed to produce the desired high level of fidelity. There is no consensus on the approach (coupled, decoupled, fine or course mesh, deterministic, stochastic or hybrid). Regardless of the approach, significant research and computational resources are envisioned. Improvements in the neutronics and burnup method must not be ignored in the development of high fidelity core simulators as it provides the heat and radiation source information required by other modules of the multi-physics simulation (computational fluid dynamic (CFD), thermal hydraulics, materials, and structural interactions) of the reactor system. That is, the fidelity of all physics processes is affected by the fidelity of the neutronics and burnup method. It must be also noted that the requirement for tight coupling of the physics processes (be it CFD, thermal hydraulics or thermal mechanical depending on the reactor type) will necessitate further research in treating the seven-variable phase space coupling issues (particularly those related to the spatial, energy and time grid). A new hybrid (stochastic/deterministic) coarse mesh radiation transport method developed at Georgia Institute of Technology for whole reactor core simulation will be briefly discussed in this presentation. (author)