Farga Niñoles, GonzaloOgando Serrano, Francisco M.Alguacil Orejudo, JavierSauvan, Patrick2025-02-122025-02-122024-05Farga-Niñoles, G., Ogando, F., Alguacil, J., & Sauvan, P. (2024). Construction of GVR weight windows maps from very low density transport simulations. Fusion Engineering and Design, 202. https://doi.org/10.1016/j.fusengdes.2024.1144170920-3796 | eISSN 1873-7196https://doi.org/10.1016/j.fusengdes.2024.114417https://hdl.handle.net/20.500.14468/25907The registered version of this article, first published in “Fusion Engineering and Design, 202", is available online at the publisher's website: Elsevier, https://doi.org/10.1016/j.fusengdes.2024.114417La versión registrada de este artículo, publicado por primera vez en “Fusion Engineering and Design, 202", está disponible en línea en el sitio web del editor: Elsevier, https://doi.org/10.1016/j.fusengdes.2024.114417Fusion-related facilities present relevant neutron radiation fields even after penetrating through a considerable thickness of shielding material. Neutronic analyses performed via Monte Carlo codes, then, need Global Variance Reduction (GVR) techniques so that low statistical uncertainty is reached efficiently throughout the geometry. Mesh-based Weight Windows is a flexible methodology used extensively for variance reduction purposes, both for Local and Global Variance Reduction. Purely stochastic GVR methodologies based on Weight Windows usually construct weight maps so that they are proportional to the forward particle flux, which is unknown a priori. Therefore, an iterative cycle is established. In each iteration, a weight map is obtained from the forward flux that allows the next iteration to reach further into the geometry, until all of it is populated. However, this iterative cycle may take a considerable amount of computer time, as many iterations are needed to fully populate the geometry. An alternative to achieve relevant penetration in a single iteration is to perform calculations at very low densities. However, a reconstruction method is needed to estimate the flux at the real density. This work studies a scheme to reconstruct the fluxes from low density calculations and compares it to already existing techniques.eninfo:eu-repo/semantics/openAccess33 Ciencias TecnológicasartículoGlobal variance reductionWeight windowsMonte Carlo particle transportMCNP