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Ogando Serrano, Francisco M.

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0000-0002-2717-4647
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Ogando Serrano
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Francisco M.
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Mostrando 1 - 3 de 3
  • Miniatura
    Publicación
    Construction of GVR weight windows maps from very low density transport simulations
    (Elsevier, 2024-05) Farga Niñoles, Gonzalo; Ogando Serrano, Francisco M.; Alguacil Orejudo, Javier; Sauvan, Patrick
    Fusion-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.
  • Miniatura
    Publicación
    Beam-facing material selection for mitigation of residual doses in the HEBT of IFMIF-DONES
    (ELSEVIER, 2024) Ogando Serrano, Francisco M.; Macià, Llorenç; López Ochoa, Víctor; Podadera Aliseda, Ivan; Sánchez Herranz, Daniel; https://orcid.org/0000-0001-5599-336X; https://orcid.org/0000-0002-3459-4631; https://orcid.org/0000-0001-7090-2550
    IFMIF-DONES will be an irradiation facility based on a 40 MeV deuteron accelerator. Unavoidable beam losses along the accelerator result in deuterium interactions with the beam facing materials of the vacuum beam pipe, some of them leading to material activation. The initial design of the beam pipe was based on stainless steel, but an evaluation of the residual doses from the pipe showed high values after operation of the accelerator. The accelerator beam line must be periodically maintained, and excessive cooling times for reaching acceptable dose levels may result in poorer availability of the facility. A deeper study of the High Energy Beam Transport line (HEBT) showed that a direct reaction between deuterons and iron in steel resulted in the production of Co-56, with a half-life of 77 days. This radioisotope is the main source of the radiation and makes it impractical to wait for a proper attenuation of the radiation field. A redesign of beam line elements has been performed to avoid the presence of stainless steel as a beam facing material and to replace it with aluminum where possible, resulting in faster decay of residual doses. This work contains a summary of the nuclear analysis performed for the computation of residual doses with stainless steel beam pipe, stressing the uncertainties of the calculations, based on the limited availability of nuclear data for the relevant nuclear reaction Fe56 (d,2n). The proposed replacement of element materials is also described, and an updated nuclear analysis shows the reduction of residual radiation, and its impact on possible maintenance operations.
  • Miniatura
    Publicación
    Preliminary nuclear analysis of HYLIFE-III: A thick-liquid-wall chamber for inertial fusion energy
    (ELSEVIER, 2024-05) Ogando Serrano, Francisco M.; Tobin, Michael T.; Meier, Wayne R.; Farga Niñoles, Gonzalo; Marian, Jaime; Reyes, Susana; Sanz Gozalo, Javier; Galloway, Conner D.
    This paper provides neutronics analyses of the Xcimer Energy Corporation (XEC) HYLIFE-III Inertial Fusion Energy Power Plant concept. This design is based on the thick-liquid-wall HYLIFE-II reactor, but with much larger fusion yield, due to enhanced driver energy. Although HYLIFE-II neutronics was extensively studied, the differences between the two concepts suggested new analyses are required. Further, computational advances in neutronics calculations also motivate updating results from more than 25 years ago. The neutron spectra emitted from the much larger yield hybrid Inertial Confinement Energy (IFE) target is presented. Selected breeding materials are compared by tritium breeding ratio (TBR), activation, and first wall protection where FLiBe is proposed as the overall best choice. The first wall neutron activation and structural damage, including gas generation in the wall, is presented for various FLiBe protective wet-wall thicknesses. Final optic neutron damage is also examined and results in optics long enough lifespan with moderate annealing temperatures. Some limited comparisons of first wall damage for ICF and Magnetic Confinement Fusion relevant conditions is presented. HYLIFE-III with FLiBe as the breeding material and first wall protection provides a very robust TBR above 1.2.