Persona: Sauvan, Patrick
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psauvan@ind.uned.es
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0000-0002-9128-8817
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Sauvan
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Patrick
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Publicación Optimizing Radiation Shielding for Fusion Maintenance Facilities: Insights From a Comprehensive Analysis of ITER Hot Cell(WILEY, 2025-05-19) Martínez Albertos, Pablo; Sauvan, Patrick; Catalán Pérez, Juan Pablo; Belotti, Mario; Javier, François; Germa, Joffrey; Tonqueze, Y. Le; Dammann, Alexis; Juárez Mañas, Rafael; ITER Organization (IO)One of the primary goals of the ITER project is to demonstrate the safety characteristics of a fusion device, particularly in terms of radiation management. Radiation protection during maintenance periods is of special concern, as personnel performing maintenance-like activities will be exposed to delayed gamma fields from numerous and complex radioactive components. Ensuring a safe and equipped environment for such activities is the objective of the ITER hot cell. This facility requires extensive design optimization, balancing spatial and temporal availability constraints, radiation protection, and cost-effectiveness. In this paper, we present a comprehensive assessment of ITER hot cell’s radiation environment to support its efficient design and safe operation. The study evaluates the shielding efficiency of the conceptual design layout from 2021, providing meaningful insights for layout improvement. We show that substantial amounts of concrete (~2900 m3) could be saved from the currently evolving design while respecting radiological requirements. The evaluation of the occupational radiation exposure (ORE) associated with hot cell maintenance activities resulted in 179 man·mSv·year−1, which represents a significant fraction (36%) of the project’s annual budget. This highlights the importance of integrating shielding analysis, accounting for personnel radiation exposure, even in early design phases, to support the optimization of the maintenance plan according to safety requirements.Publicación Nuclear scoping analysis of ITER bioshield top lid toward its preliminary design review(Elsevier, 2023-10-01) Bergman, J.; Loughlin, Martin; Le Tonqueze, Y.; Thompson, M.; Martínez Albertos, Pablo; Sauvan, Patrick; Juárez Mañas, RafaelDuring ITER operations, electronics located in the crane hall, which is above the tokamak, will be exposed to neutron and photon fields from both the plasma and the activated water. To protect the electronics, the implementation of dedicated shielding on the crane hall platform and the bioshield top lid is required. The design demands optimisation attending to constructability, weight limits, and radiation shielding requirements. This work evaluates eight shielding configurations by assessment of the neutron flux and dose accumulated over 4700 h of operation at 500 MW for electronics protection. This corresponds to a neutron wall load of 0.3 MW a/m² as specified in the ITER Project Specification. An intermediate-source approach has been followed with SRC-UNED, considering all relevant radiation sources while minimising the computational time required. Results were presented at the top lid Conceptual Design Review aiming to support decision-making. Further optimisation has since been performed to reach a top lid proposal for its Preliminary Design Review. All outcomes show that radiation levels above the north and south crane hall platforms are compatible with the critical electronics requirements.Publicación Assessment of ITER radiation environment during the remote‑handling operation of In‑Vessel components with D1SUNED(Nature Research, 2023-03-02) Martínez Albertos, Pablo; Sauvan, Patrick; Loughlin, M. J.; Tonqueze, Y. Le; Juárez Mañas, RafaelDuring ITER operational life, a remote-handled cask will be used to transfer In-Vessel components to the Hot Cell for maintenance, storage and decommissioning purposes. Due to the distribution of penetrations for system allocation in the facility, the radiation field of each transfer operation presents a high spatial variability; all operations must be studied independently for workers and electronics protection. In this paper, we present a fully representative approach to describe the radiation environment during the complete remote-handling scenario of In-Vessel components in the ITER facility. The impact of all relevant radiation sources during different stages of the operation is addressed. As-built structures and 2020 baseline designs are considered to produce the most detailed neutronics model of the Tokamak Complex, the 400,000-tonne civil structure hosting the tokamak, up to date. Novel capabilities of the D1SUNED code have allowed to compute the integral dose, the dose rate and the photon-induced neutron flux of both moving and static radiation sources. Time bins are included in the simulations to compute the dose rate caused by In-Vessel components at all positions along the transfer. The time evolution of the dose rate is built in video format with a 1-m resolution, especially valuable for hot-spots identification.Publicación Dust contamination of Divertor Remote Handling System in ITER Hot Cell: A novel approach to model complex superficial radiation sources(ELSEVIER, 2024) Martínez Albertos, Pablo; Sauvan, Patrick; Catalán Pérez, Juan Pablo; F., Javier; Le Tonquèze, Yannick; Hamilton, David Thomas; Juárez Mañas, RafaelActivated dust produced by the erosion of plasma-facing components entails a significant radiation source for ITER and, generally, for all tokamaks aiming for operation under high neutron exposure. In-Vessel remote-handling operations will mobilise the dust, which will be deposited on the remote-handling tools used, for which hands-on maintenance is expected. To ensure safe maintenance of the remote-handling equipment, a dedicated decontamination process in the Hot Cell is required. Evaluating the radiation fields produced by the contaminated equipment is central to minimising radiation exposure to personnel. In this study, we present a nuclear analysis of the Divertor Remote Handling System during its transfer and decontamination process. Past computational limitations regarding superficial sources definition and high uncertainties on the dust model have been overcome by implementing a novel methodology and following an alternative approach. Two surface-dependent dust distributions over the complex geometry surfaces were considered to evaluate the dose rates according to the different contamination levels during the process phases. A scoping analysis was performed to determine the amount of dust that would comply with project requirements in each phase of the process. Improvement margins were identified in the quantification of the amount of dust and Hot Cell layout.Publicación A full and heterogeneous model of the ITER tokamak for comprehensive nuclear analyses(Nature Research, 2021-01-04) Juárez Mañas, Rafael; Pedroche Sánchez, Gabriel; Loughlin, M. J.; Pampin, R.; Martínez Albertos, Pablo; De Pietri, Marco; Alguacil Orejudo, Javier; Ogando Serrano, Francisco M.; Sauvan, Patrick; López Revelles, Antonio Jesús; Kolsek, Aljaz; Polunovskiy, E.; Fabbri, M.; Sanz Pérez, JavierITER is the flagship project, conceived as an experiment to select and develop the technologies for the first demonstration reactor, DEMO. Nuclear analysis is a core discipline in support of the design, commissioning and operation of the machine. To date it has been conducted with increasingly detailed partial models, which represented toroidal segments of the tokamak. However, the limitations of this methodology became evident as estimates of quantities relevant to design, safety and operation showed unquantifiable uncertainties, which is a risk. Here, we present a detailed and realistic 360° MCNP model of the ITER tokamak called E-lite. We demonstrate the model’s usability and practicality. Two examples are used to illustrate qualitatively and quantitatively how it solves previously intractable problems with marked benefits for the future nuclear analysis of ITER, with applications to DEMO and future reactors. E-lite constitutes a milestone in the field of nuclear analysis in terms of realism in the evaluation of key quantities.Publicación D1SUNED system for the determination of decay photon related quantities(Elsevier, 2019-11-18) Sauvan, Patrick; Juárez Mañas, Rafael; Pedroche Sánchez, Gabriel; Alguacil Orejudo, Javier; Catalán Pérez, Juan Pablo; Ogando Serrano, Francisco M.; Sanz Pérez, JavierThe neutron fields alter the radioactive inventory of the irradiated materials leading to subsequent decay photon fields. In some cases, these fields are of relevance either intended or undesired, normally involving safety and economics aspects. The determination of these fields can be of paramount complexity if high spatial resolution is required. The determination of these fields requires both radiation transport and activation calculations. The Direct-one-Step methodology, under the assumption that the radioactive inventory activity is lineal with the neutron flux, can address the problem with only one coupled neutron-photon transport calculation. In this paper the D1SUNED code for the calculation of decay photon field and related quantities using D1S methodology is presented. Calculation capabilities including the determination of 3D decay photon sources, filtering options, and other relevant features are presented. In terms of computational load, D1SUNED, which is based on MCNP5 code, presents improvements with respect to MCNP. It can save a 79% of the RAM memory used to store the geometry, a 98% of the loading time, and an acceleration of a factor two by controlling the decay photon emission, boosting the simulations for ITER-like problems. D1SUNED has been validated with the FNG benchmark experiment considering the null hypothesis rejection test and the C/E ratio with very positive results. As a consequence, D1SUNED has become a reference tool for the design of ITER, and other relevant nuclear fusion facilities.Publicación ITER plasma source and building modelling to produce radiation maps(IOP Publishing, 2018-09-27) Juárez Mañas, Rafael; Catalán Pérez, Juan Pablo; López Revelles, Antonio Jesús; Sauvan, Patrick; Jakhar, Shrichand; Polunovskyi, Edouard; Loughlin, Michael; Sanz Gozalo, Javier; Ogando Serrano, Francisco M.The ITER Tokamak Complex is the civil structure that will host the ITER Tokamak and the largest part of the associated systems. The dimensions are 120 m × 80 m × 60 m, built mostly of concrete, with over one thousand penetrations. During ITER operation, a radiation field will spread throughout the complex from diverse radiation sources. It must be characterized to check the compliance with the limits for electronics allocation and human intervention. However, the production of radiation maps in the ITER Tokamak Complex is a task of paramount sophistication due to challenges to adequately model in MCNP the radiation sources involved. In this work, two important methodological upgrades are presented. First, a new MCNP model of the Tokamak Complex, conceived to be computationally stable while capturing a conservative representation of the baseline. Second, a novel approach to model the plasma source, called a mosaic source, allows an unprecedented degree of realism and accuracy in terms of capturing the port specificities. Both represent a step change in the capacity to produce ITER radiation maps with increased reliability, augmenting previous versions. Examples of partial radiation maps are provided considering both methodological upgrades.