Reactor Physics

Reference CE Monte Carlo power distribution for AP-1000 reactor. (hi-res image)
The Transport Rigor Implemented with Time-dependent Operation for Neutronic depletion (TRITON) control module provides flexible capabilities to meet the challenges of modern reactor designs by providing 1D pin-cell depletion capabilities using XSDRNPM, 2D lattice physics capabilities using the NEWT flexible mesh discrete ordinates code, or 3D Monte Carlo depletion using KENO V.a or KENO‑VI, including continuous energy treatment with problem-dependent temperature corrections. For multigroup analysis, TRITON implements XSProc to process material input and provide a temperature and resonance-corrected cross section library. TRITON allows users to input Dancoff factors to account for nonuniform lattices. In all cases, ORIGEN is implemented for depletion and decay calculations. Additionally, TRITON can produce assembly-averaged few group cross sections for use in core simulators. There are few limitations to the types of systems that can be modeled with TRITON, but the input complexity and long runtimes can be burdensome on users for detailed analysis.

Polaris is an optimized tool that produces assembly-averaged few group cross sections for light water reactor (LWR) analysis with core simulators. Polaris provides simplified input; only a few lines are required to describe the entire model. Polaris uses a multigroup self-shielding method called the Embedded Self-Shielding Method (ESSM) and Method-of-Characteristics (MoC) transport solver. The ESSM approach computes multigroup self‑shielded cross sections using Bondarenko interpolation. The background cross section used in the interpolation is determined by a series of 2D MoC fixed-source calculations similar to the subgroup method that does not require explicit unit cell input data. Additionally, heterogeneous lattices are explicitly treated without the need to externally compute Dancoff factors. Like TRITON, Polaris implements ORIGEN for depletion and decay calculations.

TRITON runtimes for 1470 depletion calculations. (hi-res image)