Métodos avanzados multiescala núcleo-celdas en geometrías tridimensionales y multigrupos para el cálculo de Reactores de Agua Ligera

Abstract

Advanced multi-scale pin-by-pin/core methods in three-dimensional geometries and multigroups for Light Water Reactors calculationsThe relevance of safety in the use of nuclear technology impregnates all the tasks associated to the use of this energy source, beginning with the design phase, exploitation and subsequent dismantling or waste management.In all these steps, computational simulation tools play an essential role as a guide for design, operation supporting or prediction of the reactor materials isotopic evolution.Constant improvements in computational resources from the middle of the 20 th century to this moment as well as the developments in the calculation methods employed, allow tackling the complexity of these situations with greater detail, when this was simply discarded before because of a lack of computational capacity or adequate tools.Present work is centered in the development of a neutronics calculation method for light water reactors based on corrected diffusion theory with a detail to the level of the fuel pin, considering a number of energy groups higher than the traditional fast and thermal groups, and modeling the three-dimensional geometry of the reactor core.

Monte Carlo Neutronics and Thermal-hydraulics coupling applied to Fast Reactors

“…Depending on the size of the mesh employed to solve the diffusion equation they are called nodal or pin-by-pin methods. Nevertheless the diffusion theory has been recently applied to pin-by-pin analysis of nuclear reactor applying correction factors that try to equal the diffusion solution to the transport one in all conditions and geometries [29]. Computational meshes where diffusion is solved are commonly large (coarse mesh approach) in the order of portions of fuel assemblies.…”

“…Two coupling strategies can be employed: internal coupling where each node power is transferred to a TH code and external coupling where core TH and neutronics are solved in first place and only boundary conditions are exchanged with the plant code. For instance COBAYA3, being developed by the Technical University of Madrid within the framework of the NURISM project, couples the nodal code ANDES [28] and diffusion code COBAYA3k [29] with the subchannel code COBRA-TF [30] to perform 3D coupled transient analysis in LWR cores. The results are integrated in the SALOME platform.…”

“…This simple kinetic problem has been used to compare the results of the dynamic Monte Carlo calculation and the adiabatic method with the exact solution calculated by the diffusion code COBAYA3 [29]. COBAYA3 is a pin-by-pin diffusion code that has been developed at Universidad Politécnica de Madrid (UPM) within the framework of the NURISP European project.…”