CASL is developing the Virtual Environment for Reactor Applications (VERA) as a key capability to support the analysis of the CASL Challenge Problems. VERA will include a range of physics modeling capabilities necessary to model reactors, including neutronics, thermal hydraulics, fuel performance, and coolant chemistry. Lattice physics analyses, utilizing the newly-developed Michigan lattice physics neutronics capability in MPACT 1.0, are important to CASL for several reasons:
Numerical validation of the lattice physics capability in MPACT (and its associated multi-group cross section library) is achieved by comparison of many lattice eigenvalues and normalized fission rate densities to solutions generated by two independent continuous energy (CE) Monte Carlo particle transport codes, KENO-VI and MCNP5. In addition, an analysis of a 2D 3x3 multi-assembly problem is performed and the control rod reactivity worth is also evaluated. In each of these cases MPACT is shown to provide solutions that are in excellent agreement with the reference solutions.
In addition to CE Monte Carlo results, comparisons are also made to the Westinghouse lattice physics code PARAGON. PARAGON is part of the Westinghouse in-house core physics suite that is qualified and routinely employed for the analysis of commercial PWRs. It relies on an extensive validation basis and comparison against measurements of US and world-wide PWRs and critical experiments, and is representative of the current industry state-of-the-art lattice physics tools. Comparisons between the results from PARAGON and MPACT also demonstrate that MPACT is performing very well.
After application and testing of MPACT v1.0 on many lattice physics problems, encompassing a wide range of fuel temperatures, integral and discrete burnable absorbers, control rods, and a multi-assembly controlled configuration, it is evident that MPACT has a strong capability for solving these types of problems. Figure 1 displays the eigenvalue agreement between MPACT and the CE Monte Carlo codes, and Figure 2 provides the relative pin power differences between MPACT and CE KENO-VI for the controlled 2D 3x3 sample problem.