Pub Date : 2025-04-26DOI: 10.1016/j.fusengdes.2025.115104
Xiaoyu Li , Zhi Chen
In order to ensure radiation safety and control the potential risk of tritium, the in-situ measurement technology of low radioactive concentration tritiated water has wide practical demands.A novel detector was theoretically designed utilizing plastic scintillator thin films (PSTFs) and silicon photomultiplier arrays (SiPMs) to achieve this objective. Key parameters such as sample chamber thickness, plastic scintillator thickness, and the number of sample chambers were analyzed using Monte Carlo simulations, thoroughly evaluating factors influencing energy deposition, optical transmission, detection efficiency, and minimum detectable activity concentration (MDAC). The results demonstrated that the system achieved a detection efficiency of 22.5% with the MDAC of 6.909 Bq/mL for tritiated water over a counting time of one minute. This compact and highly sensitive detector configuration is well-suited for a range of applications in environmental monitoring and radiation safety.
{"title":"In-situ detector theoretical design for low-activity concentration tritiated water based on plastic scintillator thin film flow cell","authors":"Xiaoyu Li , Zhi Chen","doi":"10.1016/j.fusengdes.2025.115104","DOIUrl":"10.1016/j.fusengdes.2025.115104","url":null,"abstract":"<div><div>In order to ensure radiation safety and control the potential risk of tritium, the in-situ measurement technology of low radioactive concentration tritiated water has wide practical demands.<strong>A novel detector was theoretically designed</strong> utilizing plastic scintillator thin films (PSTFs) and silicon photomultiplier arrays (SiPMs) to achieve this objective. Key parameters such as sample chamber thickness, plastic scintillator thickness, and the number of sample chambers were analyzed using Monte Carlo simulations, thoroughly evaluating factors influencing energy deposition, optical transmission, detection efficiency, and minimum detectable activity concentration (MDAC). The results demonstrated that the system achieved a detection efficiency of 22.5% with the MDAC of 6.909 Bq/mL for tritiated water over a counting time of one minute. This compact and highly sensitive detector configuration is well-suited for a range of applications in environmental monitoring and radiation safety.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115104"},"PeriodicalIF":1.9,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-26DOI: 10.1016/j.fusengdes.2025.115102
K.J. Büscher, A. Azka, M. Mittwollen
This paper presents the structural optimization of a mechanical multi-pipe connection (MPC), which consists of multi-pipe flange connected with a threaded bolt connection, for use in DEMO Upper Port. Mechanical pipe connections are currently being researched in the fusion context as they offer faster operating time of the pipe connections compared to conventional welded connections. However, the main consideration is that the pipe connection must be sealed against a high vacuum at both room temperature and high temperature. To ensure the necessary tightness during the entire process, the metal seals required must be sufficiently preloaded in all operating conditions. In addition, strict space availability limits the overall shape and dimension of the MPC. For this purpose, a structural analysis and subsequent topology optimization of the flange connection is carried out using the commercially available FEA software Abaqus®. The result of the topology optimization, taking into account suitable boundary conditions, is a design for the flange which, in addition to achieving sufficient deformation of the seals throughout, also smoothed out the stress peaks present in previous designs. However, the design cannot yet be produced in its current form, as cavities have also been created within the flange. The manufacturability of the flange must therefore be investigated in a subsequent second step and the design adapted accordingly. In this paper, a design draft of a MPC for use in DEMO Upper Port is presented, which fulfills all the necessary boundary conditions, but still needs to be revised regarding its manufacturability.
{"title":"Structural analysis and optimization of mechanical multi-pipe connection for DEMO Upper Port","authors":"K.J. Büscher, A. Azka, M. Mittwollen","doi":"10.1016/j.fusengdes.2025.115102","DOIUrl":"10.1016/j.fusengdes.2025.115102","url":null,"abstract":"<div><div>This paper presents the structural optimization of a mechanical multi-pipe connection (MPC), which consists of multi-pipe flange connected with a threaded bolt connection, for use in DEMO Upper Port. Mechanical pipe connections are currently being researched in the fusion context as they offer faster operating time of the pipe connections compared to conventional welded connections. However, the main consideration is that the pipe connection must be sealed against a high vacuum at both room temperature and high temperature. To ensure the necessary tightness during the entire process, the metal seals required must be sufficiently preloaded in all operating conditions. In addition, strict space availability limits the overall shape and dimension of the MPC. For this purpose, a structural analysis and subsequent topology optimization of the flange connection is carried out using the commercially available FEA software <span>Abaqus</span>®. The result of the topology optimization, taking into account suitable boundary conditions, is a design for the flange which, in addition to achieving sufficient deformation of the seals throughout, also smoothed out the stress peaks present in previous designs. However, the design cannot yet be produced in its current form, as cavities have also been created within the flange. The manufacturability of the flange must therefore be investigated in a subsequent second step and the design adapted accordingly. In this paper, a design draft of a MPC for use in DEMO Upper Port is presented, which fulfills all the necessary boundary conditions, but still needs to be revised regarding its manufacturability.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115102"},"PeriodicalIF":1.9,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-26DOI: 10.1016/j.fusengdes.2025.115075
P. Balazs , O. Asztalos , M.S. Fonyi , S. Thomas , D. Dunai , G.I. Pokol , MAST-U Team
The MAST-U beam emission spectroscopy (BES) diagnostic measures D emission from the on-axis neutral deuterium heating beam. From the measured light intensity variations, the local density fluctuations can be characterized, which is a valuable method to study both core and edge plasma turbulence, as well as various MHD phenomena. The predecessor 2D turbulence imaging BES diagnostic system was installed on MAST in 2010, with the first mirror location optimized so that measurements had the best achievable poloidal and radial resolution at a specific observation location along the beam. This system was operational in the M8 and M9 campaigns and was successfully used in several physics programs. In the MAST Upgrade, the BES system was relocated due to technical constraints and installed in a dedicated port. The assessment of the new configuration’s spatial resolution was required so that the measurements could be interpreted correctly and consistently. The spatial resolution assessment was performed for multiple observation locations covering the minor radius of the device. Our study concentrated on the dominant smearing caused by the misalignment between the lines of sight and the magnetic field lines within the beam geometry. For comparison, the same analysis was also performed on pre-upgrade scenarios. The relocation of the observation system had a slightly negative effect on the poloidal resolution due to an increase in the misalignment between the lines of sight and the magnetic field lines at the beam location. However, the values in general remain in the region of the old setup, posing no obstacle to the continued utilization of the system for density fluctuation measurements.
{"title":"Assessment of magnetic smearing effects for the MAST-U beam emission spectroscopy system","authors":"P. Balazs , O. Asztalos , M.S. Fonyi , S. Thomas , D. Dunai , G.I. Pokol , MAST-U Team","doi":"10.1016/j.fusengdes.2025.115075","DOIUrl":"10.1016/j.fusengdes.2025.115075","url":null,"abstract":"<div><div>The MAST-U beam emission spectroscopy (BES) diagnostic measures D<span><math><msub><mrow></mrow><mrow><mi>α</mi></mrow></msub></math></span> emission from the on-axis neutral deuterium heating beam. From the measured light intensity variations, the local density fluctuations can be characterized, which is a valuable method to study both core and edge plasma turbulence, as well as various MHD phenomena. The predecessor 2D turbulence imaging BES diagnostic system was installed on MAST in 2010, with the first mirror location optimized so that measurements had the best achievable poloidal and radial resolution at a specific observation location along the beam. This system was operational in the M8 and M9 campaigns and was successfully used in several physics programs. In the MAST Upgrade, the BES system was relocated due to technical constraints and installed in a dedicated port. The assessment of the new configuration’s spatial resolution was required so that the measurements could be interpreted correctly and consistently. The spatial resolution assessment was performed for multiple observation locations covering the minor radius of the device. Our study concentrated on the dominant smearing caused by the misalignment between the lines of sight and the magnetic field lines within the beam geometry. For comparison, the same analysis was also performed on pre-upgrade scenarios. The relocation of the observation system had a slightly negative effect on the poloidal resolution due to an increase in the misalignment between the lines of sight and the magnetic field lines at the beam location. However, the values in general remain in the region of the old setup, posing no obstacle to the continued utilization of the system for density fluctuation measurements.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115075"},"PeriodicalIF":1.9,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-26DOI: 10.1016/j.fusengdes.2025.115080
Matteo Lo Verso , Stefano Riva , Carolina Introini , Eric Cervi , Luciana Barucca , Marco Caramello , Matteo Di Prinzio , Francesca Giacobbo , Laura Savoldi , Antonio Cammi
Magnetohydrodynamics (MHD) studies the dynamics of electrically conducting fluids under the influence of a magnetic field and it is relevant in several nuclear applications. However, the high computational cost of multi-physics MHD simulations poses a challenge. Reduced Order Modelling (ROM) offers a promising alternative, enabling lower-dimensional approximations while preserving accuracy. This allows for a reduction in the computational time and, at the same time, accurate approximations of the intricate physics involved in fusion reactors. However, ROM techniques are relatively new within the MHD framework, and benchmark test cases should be considered in this first stage for verification and validation. Therefore, this study applies the ROM methodology to a MHD scenario to study their potentialities (and eventual criticalities) for this class of problems. The benchmark test case considered in this work is the Backward-Facing Step. The obtained results contribute to assessing the capabilities of ROM methodologies in MHD scenarios, demonstrating their potential to enhance computational efficiency in this field and representing a critical step towards advancing the computational modelling of complex systems in nuclear fusion.
{"title":"Enhancing computational efficiency in nuclear fusion through reduced order modelling: Applications in magnetohydrodynamics","authors":"Matteo Lo Verso , Stefano Riva , Carolina Introini , Eric Cervi , Luciana Barucca , Marco Caramello , Matteo Di Prinzio , Francesca Giacobbo , Laura Savoldi , Antonio Cammi","doi":"10.1016/j.fusengdes.2025.115080","DOIUrl":"10.1016/j.fusengdes.2025.115080","url":null,"abstract":"<div><div>Magnetohydrodynamics (MHD) studies the dynamics of electrically conducting fluids under the influence of a magnetic field and it is relevant in several nuclear applications. However, the high computational cost of multi-physics MHD simulations poses a challenge. Reduced Order Modelling (ROM) offers a promising alternative, enabling lower-dimensional approximations while preserving accuracy. This allows for a reduction in the computational time and, at the same time, accurate approximations of the intricate physics involved in fusion reactors. However, ROM techniques are relatively new within the MHD framework, and benchmark test cases should be considered in this first stage for verification and validation. Therefore, this study applies the ROM methodology to a MHD scenario to study their potentialities (and eventual criticalities) for this class of problems. The benchmark test case considered in this work is the Backward-Facing Step. The obtained results contribute to assessing the capabilities of ROM methodologies in MHD scenarios, demonstrating their potential to enhance computational efficiency in this field and representing a critical step towards advancing the computational modelling of complex systems in nuclear fusion.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115080"},"PeriodicalIF":1.9,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-25DOI: 10.1016/j.fusengdes.2025.115068
M.A. Vázquez-Barroso , C. Torregrosa-Martín , J. Maestre
IFMIF-DONES will be a radiological facility for material irradiation replicating conditions expected in future fusion reactors. It will employ a 40 MeV deuteron beam directed at a liquid Li target circulating at 15 m/s to generate high-energy neutrons, depositing 5 MW. The Back-Plate (BP), placed immediately downstream of the Li, separates the vacuum of the accelerator and target chambers from the low-pressure He atmosphere housing the irradiation modules. A critical scenario postulates an eventual loss of liquid Li curtain thickness without shutting down the beam, risking a direct or partial deuteron beam impact on the BP causing large power deposition. This study provides the BP dynamic thermomechanical response, aiming at characterizing the involved timings in the impact-triggered events, such as mechanical failure, melting or vaporization. This is important to evaluate the eventual mobilization of the BP volatilized activated material and the available timings for beam shutdown. The methodology involves Monte-Carlo simulations for power deposition data integrated into a Finite Element model in ANSYS for transient thermal and structural analyses. Results include timings for melting, vaporization, and mechanical response as function of the beam footprint area and the Li jet thickness reduction.
IFMIF-DONES 将是一个复制未来聚变反应堆预期条件的材料辐照辐射设施。它将使用一束 40 兆电子伏的氘核射束，射向以 15 米/秒速度循环的液态锂靶，产生高能中子，沉积 5 兆瓦。背板（BP）紧靠液态锂下游，将加速器和靶室的真空与容纳辐照模块的低压 He 大气隔开。在不关闭光束的情况下，液态锂帘的厚度可能会最终丧失，这就有可能导致氘核光束直接或部分撞击 BP，造成大量功率沉积。这项研究提供了 BP 的动态热机械响应，目的是确定撞击触发事件（如机械故障、熔化或汽化）的相关时间特征。这对于评估 BP 活性材料的最终挥发以及光束关闭的可用时间非常重要。该方法包括对功率沉积数据进行蒙特卡洛模拟，并将其集成到 ANSYS 的有限元模型中，以进行瞬态热分析和结构分析。结果包括熔化、汽化和机械响应的时间，这与光束足迹面积和锂射流厚度的减少有关。
{"title":"Thermomechanical failure analysis of IFMIF-DONES target under off-nominal extreme conditions","authors":"M.A. Vázquez-Barroso , C. Torregrosa-Martín , J. Maestre","doi":"10.1016/j.fusengdes.2025.115068","DOIUrl":"10.1016/j.fusengdes.2025.115068","url":null,"abstract":"<div><div>IFMIF-DONES will be a radiological facility for material irradiation replicating conditions expected in future fusion reactors. It will employ a 40 MeV deuteron beam directed at a liquid Li target circulating at 15 m/s to generate high-energy neutrons, depositing 5 MW. The Back-Plate (BP), placed immediately downstream of the Li, separates the vacuum of the accelerator and target chambers from the low-pressure He atmosphere housing the irradiation modules. A critical scenario postulates an eventual loss of liquid Li curtain thickness without shutting down the beam, risking a direct or partial deuteron beam impact on the BP causing large power deposition. This study provides the BP dynamic thermomechanical response, aiming at characterizing the involved timings in the impact-triggered events, such as mechanical failure, melting or vaporization. This is important to evaluate the eventual mobilization of the BP volatilized activated material and the available timings for beam shutdown. The methodology involves Monte-Carlo simulations for power deposition data integrated into a Finite Element model in <span>ANSYS</span> for transient thermal and structural analyses. Results include timings for melting, vaporization, and mechanical response as function of the beam footprint area and the Li jet thickness reduction.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115068"},"PeriodicalIF":1.9,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-25DOI: 10.1016/j.fusengdes.2025.115071
O. Kudláček , W. Treutterer , I. Gomez Ortiz , P.T. Lang , R. Nouailletas , L. Pangione , M. Reich , S. Stanek , P. de Vries , A. Vu , D. Weldon , L. Zabeo
An important goal of the Start of Research Operation (SRO) at ITER is the commissioning of the Plasma Control System (PCS) and the testing of algorithms for heating and MHD, shape, error field, density, reaching H-mode, and ELM control. The ITER PCS will utilize magnetic actuators (error field coils, poloidal field coils), fueling actuators (4 pellet injectors connectable to 6 pellet flight tubes, 60 gas valves), and heating actuators (48 gyrotrons connectable to 9 steerable mirrors and 1 ICRH antenna). This contribution focuses on the development of the Actuator Management (AM) for the fueling and heating actuators.
The purpose of the AM is to link controllers to multi-purpose actuators in order to properly manage conflicting requests, simplify the PCS architecture and increase its robustness. It is achieved by aggregating all of the fueling and heating actuators that have a similar impact on the plasma into Virtual Actuators (VA), which are treated as single entities by the controllers. The VAs provide the actuation limits to the controllers and distribute the controller command amongst their member actuators. It simplifies the controller design, increases its actuation amplitude, and robustness against actuator faults.
This contribution details the generic AM architecture and its extensions for specific features of the above listed control tasks using the actuators that are foreseen at ITER. In particular, we will present a method to treat actuators with steerable launchers, and a way to orchestrate pellet firing for both fueling and ELM pacing control tasks.
The presented algorithms are to be implemented into the ITER PCS and used for its operation in the SRO phase.
{"title":"Actuator management for the first ITER plasma operation campaign","authors":"O. Kudláček , W. Treutterer , I. Gomez Ortiz , P.T. Lang , R. Nouailletas , L. Pangione , M. Reich , S. Stanek , P. de Vries , A. Vu , D. Weldon , L. Zabeo","doi":"10.1016/j.fusengdes.2025.115071","DOIUrl":"10.1016/j.fusengdes.2025.115071","url":null,"abstract":"<div><div>An important goal of the Start of Research Operation (SRO) at ITER is the commissioning of the Plasma Control System (PCS) and the testing of algorithms for heating and MHD, shape, error field, density, reaching H-mode, and ELM control. The ITER PCS will utilize magnetic actuators (error field coils, poloidal field coils), fueling actuators (4 pellet injectors connectable to 6 pellet flight tubes, 60 gas valves), and heating actuators (48 gyrotrons connectable to 9 steerable mirrors and 1 ICRH antenna). This contribution focuses on the development of the Actuator Management (AM) for the fueling and heating actuators.</div><div>The purpose of the AM is to link controllers to multi-purpose actuators in order to properly manage conflicting requests, simplify the PCS architecture and increase its robustness. It is achieved by aggregating all of the fueling and heating actuators that have a similar impact on the plasma into Virtual Actuators (VA), which are treated as single entities by the controllers. The VAs provide the actuation limits to the controllers and distribute the controller command amongst their member actuators. It simplifies the controller design, increases its actuation amplitude, and robustness against actuator faults.</div><div>This contribution details the generic AM architecture and its extensions for specific features of the above listed control tasks using the actuators that are foreseen at ITER. In particular, we will present a method to treat actuators with steerable launchers, and a way to orchestrate pellet firing for both fueling and ELM pacing control tasks.</div><div>The presented algorithms are to be implemented into the ITER PCS and used for its operation in the SRO phase.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115071"},"PeriodicalIF":1.9,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1016/j.fusengdes.2025.115065
Ciro Alberghi , Luigi Candido , Daniele Martelli , Francesca Papa , Marco Utili , Alessandro Venturini
Tritium extraction from lithium-lead (PbLi, 15.7 at. % Li) and tritium concentration measurement in the eutectic alloy represent some of the most challenging aspects of the R&D activities aimed to the development of ITER and the European DEMO reactor. To efficiently design Permeator Against Vacuum (PAV) systems and Hydrogen isotopes Permeation Sensors (HPS), theoretical models for the evaluation of the permeation flux have been proposed in literature, but methodologies for the improvement of their performances are still lacking. In this paper a new concept of finned permeator is analysed, leveraging the analogy between mass transport and heat transfer. In PAV and HPS, the low-pressure side is usually kept under medium/high vacuum conditions and surface phenomena can play an important role, especially when the membrane presents oxidation. The fin approach is particularly effective in these cases, where transport kinetics is dominated by surface effects (diffusion in the bulk is relatively fast) and can be used as a method to increase the permeation of hydrogen isotopes with limited increase in system size. Within the paper, the mathematical model for the extended surface placed on the vacuum side is derived and simple relations for design parameters for the finned surface, like fin efficiency and effectiveness, are derived. The solution of this analytical model is compared with numerical results for a PAV system with niobium membrane under relevant conditions for DEMO reactor.
{"title":"Fins: Improving tritium extraction systems and permeation sensors with the adoption of extended surfaces","authors":"Ciro Alberghi , Luigi Candido , Daniele Martelli , Francesca Papa , Marco Utili , Alessandro Venturini","doi":"10.1016/j.fusengdes.2025.115065","DOIUrl":"10.1016/j.fusengdes.2025.115065","url":null,"abstract":"<div><div>Tritium extraction from lithium-lead (PbLi, 15.7 at. % Li) and tritium concentration measurement in the eutectic alloy represent some of the most challenging aspects of the R&D activities aimed to the development of ITER and the European DEMO reactor. To efficiently design Permeator Against Vacuum (PAV) systems and Hydrogen isotopes Permeation Sensors (HPS), theoretical models for the evaluation of the permeation flux have been proposed in literature, but methodologies for the improvement of their performances are still lacking. In this paper a new concept of finned permeator is analysed, leveraging the analogy between mass transport and heat transfer. In PAV and HPS, the low-pressure side is usually kept under medium/high vacuum conditions and surface phenomena can play an important role, especially when the membrane presents oxidation. The fin approach is particularly effective in these cases, where transport kinetics is dominated by surface effects (diffusion in the bulk is relatively fast) and can be used as a method to increase the permeation of hydrogen isotopes with limited increase in system size. Within the paper, the mathematical model for the extended surface placed on the vacuum side is derived and simple relations for design parameters for the finned surface, like fin efficiency and effectiveness, are derived. The solution of this analytical model is compared with numerical results for a PAV system with niobium membrane under relevant conditions for DEMO reactor.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115065"},"PeriodicalIF":1.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1016/j.fusengdes.2025.115038
Daniel Ahlin Heikkinen Wartacz , Johann Riesch , Karen Pantleon , Wolfgang Pantleon
Fusion energy holds great promise as a sustainable solution to meet global energy demands, offering a quasi-inexhaustible, secure and environmentally friendly energy resource. Materials facing the burning plasma in fusion reactors must withstand extreme conditions. Tungsten, the current choice for plasma-facing materials, is at risk of embrittlement if exposed to high temperatures due to restoration processes increasing its ductile-to-brittle transition temperature. This embrittlement limits operation of tungsten under fusion-relevant conditions. Tungsten fiber-reinforced tungsten (W/W) composites are developed to mitigate brittleness and achieve pseudo-ductile behavior, utilizing drawn, potassium-doped tungsten fibers embedded in a pure tungsten matrix to enhance toughness compared to pure tungsten significantly. In view of the high heat fluxes and the expected high steady-state operation temperatures in a fusion reactor, thermal stability of the plasma-facing material becomes crucial. Model W/W systems containing a single tungsten fiber in a dense tungsten matrix, with or without an yttria interlayer, are annealed at 1450 °C for up to 2 days to evaluate their thermal stability. As the tungsten fibers are primarily responsible for the pseudo-ductile behavior, this investigation focuses on analyzing the thermal stability of the fibers and their immediate vicinity in the surrounding matrix. Changes within the tungsten fibers, including alterations of boundary spacing and crystallographic texture, are analyzed using electron backscatter diffraction (EBSD) and further post-processing of the orientation data. Quantification shows a substantial increase in boundary spacing in the fibers after annealing. This indicates recrystallization, where many boundaries with disorientation angles up to 50°are removed. The crystallographic texture in the fibers changes only slightly during annealing, if at all.
{"title":"Restoration in drawn tungsten wires of tungsten fiber-reinforced tungsten composites","authors":"Daniel Ahlin Heikkinen Wartacz , Johann Riesch , Karen Pantleon , Wolfgang Pantleon","doi":"10.1016/j.fusengdes.2025.115038","DOIUrl":"10.1016/j.fusengdes.2025.115038","url":null,"abstract":"<div><div>Fusion energy holds great promise as a sustainable solution to meet global energy demands, offering a quasi-inexhaustible, secure and environmentally friendly energy resource. Materials facing the burning plasma in fusion reactors must withstand extreme conditions. Tungsten, the current choice for plasma-facing materials, is at risk of embrittlement if exposed to high temperatures due to restoration processes increasing its ductile-to-brittle transition temperature. This embrittlement limits operation of tungsten under fusion-relevant conditions. Tungsten fiber-reinforced tungsten (W<span><math><msub><mrow></mrow><mrow><mi>f</mi></mrow></msub></math></span>/W) composites are developed to mitigate brittleness and achieve pseudo-ductile behavior, utilizing drawn, potassium-doped tungsten fibers embedded in a pure tungsten matrix to enhance toughness compared to pure tungsten significantly. In view of the high heat fluxes and the expected high steady-state operation temperatures in a fusion reactor, thermal stability of the plasma-facing material becomes crucial. Model W<span><math><msub><mrow></mrow><mrow><mi>f</mi></mrow></msub></math></span>/W systems containing a single tungsten fiber in a dense tungsten matrix, with or without an yttria interlayer, are annealed at 1450 °C for up to 2 days to evaluate their thermal stability. As the tungsten fibers are primarily responsible for the pseudo-ductile behavior, this investigation focuses on analyzing the thermal stability of the fibers and their immediate vicinity in the surrounding matrix. Changes within the tungsten fibers, including alterations of boundary spacing and crystallographic texture, are analyzed using electron backscatter diffraction (EBSD) and further post-processing of the orientation data. Quantification shows a substantial increase in boundary spacing in the fibers after annealing. This indicates recrystallization, where many boundaries with disorientation angles up to 50°are removed. The crystallographic texture in the fibers changes only slightly during annealing, if at all.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115038"},"PeriodicalIF":1.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1016/j.fusengdes.2025.115077
Fabio Veronese , Piero Agostinetti , Andrea Murari
Neutral Beam Injectors (NBIs) are key components in the additional heating of the tokamak plasmas. In this scheme, fast charged ions are accelerated electrostatically by suitable grids and then neutralized through a gas target in a dedicated neutralizer, in order to penetrate the strong confining magnetic field. NBIs require a powerful Gas Vacuum System (GVS) in order to operate, and any simplification to this element has a positive impact on the wall-plug efficiency of the NBI, as well as on the overall procurement. In this paper, new design concepts that rely on the Gaede effect are proposed for the neutralizer: their objective is the reduction of the gas conductance through the component by means of appropriate shaping of the internal walls, while maintaining enough clearance for the fast beam to pass through. In this way, the same gas target can be achieved with a reduced neutral gas input, decreasing the throughput that the GVS must be able to evacuate. This work gives a description of the application of this concept to the Divertor Tokamak Test (DTT)’s own NBI, which has been carried out by comparing different design options by means of several simulations with various vacuum codes. Due to the significant improvement that the Gaede effect is expected to bring to the NBI gas economy, this design application has been patented and will be proposed to be implemented in the NBI of the DTT facility, under construction in Frascati (Italy).
{"title":"Application of the Gaede effect to the neutralizer of DTT neutral beam injector","authors":"Fabio Veronese , Piero Agostinetti , Andrea Murari","doi":"10.1016/j.fusengdes.2025.115077","DOIUrl":"10.1016/j.fusengdes.2025.115077","url":null,"abstract":"<div><div>Neutral Beam Injectors (NBIs) are key components in the additional heating of the tokamak plasmas. In this scheme, fast charged ions are accelerated electrostatically by suitable grids and then neutralized through a gas target in a dedicated neutralizer, in order to penetrate the strong confining magnetic field. NBIs require a powerful Gas Vacuum System (GVS) in order to operate, and any simplification to this element has a positive impact on the wall-plug efficiency of the NBI, as well as on the overall procurement. In this paper, new design concepts that rely on the Gaede effect are proposed for the neutralizer: their objective is the reduction of the gas conductance through the component by means of appropriate shaping of the internal walls, while maintaining enough clearance for the fast beam to pass through. In this way, the same gas target can be achieved with a reduced neutral gas input, decreasing the throughput that the GVS must be able to evacuate. This work gives a description of the application of this concept to the Divertor Tokamak Test (DTT)’s own NBI, which has been carried out by comparing different design options by means of several simulations with various vacuum codes. Due to the significant improvement that the Gaede effect is expected to bring to the NBI gas economy, this design application has been patented and will be proposed to be implemented in the NBI of the DTT facility, under construction in Frascati (Italy).</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115077"},"PeriodicalIF":1.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-24DOI: 10.1016/j.fusengdes.2025.115116
S. Giors , F. Adong , O. Barana , A. Barturen Montes , F. Dhalla , S. Jachmich , V. Kulaev , U. Kruezi , N. Luchier , J. Manzagol , F. Millet , M. Parekh , A. Rizzato
The ITER tokamak will be equipped with a machine protection system to avoid or mitigate the damage to its in-vessel components in the event of plasma disruptions. The Disruption Mitigation System (DMS) will be based on Injection of Shattered Pellets (SPI) made of hydrogen, neon or their mixtures into the plasma, to convert the plasma energy into radiation while avoiding the formation or dissipate the energy of runaway electrons and to minimize the electromagnetic loads by controlling the plasma current quench.
To achieve the disruption mitigation requirements and fulfill the pulse rate for the ITER Research Plan, the DMS Cryogenic Distribution System (CDS) shall form cylindrical pellets with a diameter of 28.5 mm, a length of 57 mm and good integrity, by de-sublimation of gases inside a Supercritical helium (SHe) cooled Cold Cell (CC), in ≈1200 s (20 min) for hydrogen, and maintain their availability over several plasma pulses.
The DMS CDS was integrated into the ITER baseline at a late design stage, with limited SHe cooling capacity supplied in parallel to the cryopumps for vacuum vessel, cryostat and neutral beam injectors. Seven Cold Distribution Boxes (CDBs) dedicated to the DMS equatorial and upper port locations were introduced, each equipped with a Joule-Thompson (JT) expansion valve and a liquid helium vessel, to supply the SHe flow to 27 CCs at a stable temperature of ∼5 K for pellet formation and preservation. The CC design was supported by de-sublimation numerical modelling and experiments to optimize the pellet shape and integrity and to minimize the CC cooling requirement to form pellets within an acceptable time. The cryogenic system design aimed at minimizing heat losses while considering the very challenging environmental (magnetic field, nuclear, seismic) and complex integration requirements.
This paper presents the DMS CDS description, following the final design review in 2024, focusing on the CC novel design supported by CFD models and laboratory experiments.
{"title":"Design of the cryogenic distribution system for the ITER disruption mitigation based on shattered pellet injection","authors":"S. Giors , F. Adong , O. Barana , A. Barturen Montes , F. Dhalla , S. Jachmich , V. Kulaev , U. Kruezi , N. Luchier , J. Manzagol , F. Millet , M. Parekh , A. Rizzato","doi":"10.1016/j.fusengdes.2025.115116","DOIUrl":"10.1016/j.fusengdes.2025.115116","url":null,"abstract":"<div><div>The ITER tokamak will be equipped with a machine protection system to avoid or mitigate the damage to its in-vessel components in the event of plasma disruptions. The Disruption Mitigation System (DMS) will be based on Injection of Shattered Pellets (SPI) made of hydrogen, neon or their mixtures into the plasma, to convert the plasma energy into radiation while avoiding the formation or dissipate the energy of runaway electrons and to minimize the electromagnetic loads by controlling the plasma current quench.</div><div>To achieve the disruption mitigation requirements and fulfill the pulse rate for the ITER Research Plan, the DMS Cryogenic Distribution System (CDS) shall form cylindrical pellets with a diameter of 28.5 mm, a length of 57 mm and good integrity, by de-sublimation of gases inside a Supercritical helium (SHe) cooled Cold Cell (CC), in ≈1200 s (20 min) for hydrogen, and maintain their availability over several plasma pulses.</div><div>The DMS CDS was integrated into the ITER baseline at a late design stage, with limited SHe cooling capacity supplied in parallel to the cryopumps for vacuum vessel, cryostat and neutral beam injectors. Seven Cold Distribution Boxes (CDBs) dedicated to the DMS equatorial and upper port locations were introduced, each equipped with a Joule-Thompson (JT) expansion valve and a liquid helium vessel, to supply the SHe flow to 27 CCs at a stable temperature of ∼5 K for pellet formation and preservation. The CC design was supported by de-sublimation numerical modelling and experiments to optimize the pellet shape and integrity and to minimize the CC cooling requirement to form pellets within an acceptable time. The cryogenic system design aimed at minimizing heat losses while considering the very challenging environmental (magnetic field, nuclear, seismic) and complex integration requirements.</div><div>This paper presents the DMS CDS description, following the final design review in 2024, focusing on the CC novel design supported by CFD models and laboratory experiments.</div></div>","PeriodicalId":55133,"journal":{"name":"Fusion Engineering and Design","volume":"216 ","pages":"Article 115116"},"PeriodicalIF":1.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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