Improvement of computer code DRAGON5 for providing support to safety assessment, criticality studies and core simulation of nuclear reactors

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Neutronics deterministic simulations are based on two software components, one dedicated to the unit fuel assembly and the other dedicated to the full core. The more complex one is the lattice code based on a solution of the Boltzmann equation for neutrons and on specific models. It is used for criticality safety and for reactor physics applications by feeding the full core simulation code with a multi-parameter database. In the last 30 years, École Polytechnique de MontrÉal (EPM) has developed the lattice code DRAGON, now at Version 5, and a 3D diffusion code named DONJON for full core simulations. These two codes are widely distributed across the world under an open-source license and are used by many universities and organizations who are becoming expert users of DRAGON/DONJON.***The numerical performance of the solution algorithms for the Boltzmann equation has a strong effect on both the accuracy and the CPU-effectiveness of DRAGON. The short-term objective of this NSERC/DG program is to study the mathematical foundations, accuracy and acceleration issues related to the basic numerical technique used in modern lattice code, in a way to improve the overall performances of DRAGON V5. The long-term objective is to provide software tools and computational schemes to the nuclear industry that will enable them to assess the performance and safety characteristics of existing and new types of nuclear reactors. The first two sub-projects focus on deterministic solution techniques of the Boltzmann equation: (1) Development of a discrete ordinates (SN) method with a Discontinuous Galerkin (DG) scheme; (2) Improve the method of characteristics (MOC) and develop the first-order algebraic collapsing (FOAC) method. Three more sub-projects are defined in order to develop and validate computational schemes based on the most recent advances available in DRAGON V5: (3) Development of two-level computational schemes for PWR (pressurized water reactor) lattices, (4) Development of two-level computational schemes for ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) lattices, (5) Development of micro-depletion capabilities for ASTRID-type full-core simulations.***Subjects related to the development or improvement of solution techniques for the Boltzmann equation are clearly of the Ph.D. level. Development of the one- and two-level computational schemes in CLE-2000 language and their code-to-code validation with respect to burnup-dependent Monte Carlo simulations is of the level of M.Eng. students. The three M.Eng. sub-projects will be investigated in close relationship with industrial partners such as IRSN and GRS, keeping our focus on production applications.**