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• MCUNED-Plus code implements the Direct-1-Step methodology to the simulation of residual fields in particle accelerator-based facilities. • The new developments improve the accuracy and performance for the simulation of prompt and residual radiation fields from precedent tools. • The Direct-1-Step in particle accelerators has proven to yield very similar results compared to other well stablished methodologies like the Rigorous-2-Steps. The radiation hazard is one of the major aspects of concern in the design of a facility where it exists a risk of exposure to ionizing radiation. The nuclear analysis for radioprotection purposes requires an accurate description of the radiation fields. This is especially true in accelerator-based facilities where several types of particles are producing the radiation fields. Radiation fields exist during the accelerator operation, but delayed radiation may also be significant for a long time after operation ends. The radiation fields of concern present during the operation are due to the secondary neutrons and photons emitted by the interaction of accelerated particles with the accelerator components (beam leakage) or with the target. The radiation present after the operation is the residual photon field produced by activated materials, these materials being activated by both accelerated particles and secondary neutrons. This residual radiation field is relevant in high intensity accelerators like IFMIF-DONES. In order to address these complex radiation transport simulations, the D1SUNED code has been updated and the new code release renamed as MCUNED-Plus. The new developments include improvements in the light-ion transport like the implementation of a variance reduction for the production of secondary particles, and a new kinematics to reproduce the angular distribution of secondary particles emitted after deuteron breakup reaction. The calculation of the residual photon field in accelerator facility has also been improved by allowing to evaluate both light-ions and secondary neutrons induced shutdown dose rate in a single coupled simulation. [ABSTRACT FROM AUTHOR]

Fusion test facilities are expansive, intricate structures designed to test materials for fusion power plants. For a seamless testing process, it's crucial that the machinery and equipment within these facilities are consistently maintained and promptly replaced if they fail. This necessitates the transportation of large, heavy machinery and equipment through the facility's narrow corridors, doors, hatches, and shipping bays. Taking the DEMO oriented neutron source (DONES) as a case study, we illustrate the complexities of material flow planning in such environments, detailing strategies to navigate these challenges and organize material flow planning efficiently and safely. We introduce a methodology for executing various stages of material flow planning in these contexts and discuss how uncertainties impact the planning process. The primary hurdles include gathering data on machinery and equipment and the facility's layout, converting this data into actionable transport plans and routes, providing precise transport instructions, and verifying the viability of the material flow. We propose and implement a comprehensive solution to these challenges at DONES, encompassing data collection techniques, the creation of a modular transport system, a universal model for transport processes in intralogistics, and a simulation tool for swift and effective collision checks between transport devices, machinery, equipment, and the building structure. A significant insight from this approach is the high value of automating the process, as uncertainties frequently alter data, necessitating regular updates to the material flow plan. [ABSTRACT FROM AUTHOR]

One of the crucial steps in the European Roadmap to the realisation of fusion energy is the design and construction of the Demo-orientated NEutron Source (DONES) facility. DONES is a fusion-like neutron source, based on the International Fusion Materials Irradiation Facility (IFMIF) concept, aimed at qualifying and testing the materials to be used in fusion reactors. The Target System (TSY) is a crucial system as it is the component where the interactions between deuterons and a liquid lithium target, flowing on a solid surface (i.e. the Back Plate), take place to produce neutrons for irradiating the testing materials. In this regard, an investigation campaign has been performed to evaluate the thermo-mechanical behaviour of the DONES TSY under selected steady state and transient loading conditions, in light of the most recent design updates (new bellows and connection systems). The first part of the assessment concerned the analysis of the TSY under the normal operation steady state loading scenario. A detailed 3D FEM model has been set up, considering the newest updates of the TSY geometry and of the operational parameters, and a thermo-mechanical analysis has been launched. Results have been mainly checked in terms of TSY global deformation, focusing on the Back Plate and on the connecting bellows displacements, in order to exclude overlapping with the High Flux Test Module and misalignments with the beam footprint. Afterwards, since the lithium inlet temperature has been increased from 250 °C to 300 °C, a transient thermo-mechanical analysis of the TSY under the start-up loading conditions has been performed to check if it is able to withstand the hotter lithium flow according to the RCC-MRx criteria. Therefore, the reference pre-heating strategy has been adopted, assessing the thermal and mechanical behaviour of the TSY, focusing on the Back Plate. The obtained results are presented and critically discussed, suggesting important recommendations for the follow-up of the design. [ABSTRACT FROM AUTHOR]

In IFMIF-DONES, a deuteron beam will impinge on a flowing liquid lithium target, resulting in an intense neutron source. Other radiation sources will also arise due to the interactions between deuterons and the beam facing accelerator components. These radiation fields may cause some negative effects, such as damage to equipment or the generation of residual radiation sources. The characterization and mitigation of all the radiation sources are crucial for a safe operation and maintenance of the facility. In this study, the optimization and/or implementation of some radiation shields located in critical areas is considered to reduce the doses during operation and shutdown. Three scenarios are assessed: (i) shielding optimization of the High-Power Beam Dump for the accelerator commissioning, (ii) shielding optimization for the scraper of the High Energy Beam Transport line and the Fast Safety Isolation Valves, and (iii) shielding implementation to reduce the radiation transmission through Heating, Ventilation, and Air Conditioning wall penetrations. Radiation maps of the biological dose and the dose to silicon are computed, showing the impact of such shielding elements. [ABSTRACT FROM AUTHOR]

During the installation and maintenance phase of IFMIF-DONES (International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source), several components need to be transported vertically between different floors inside the DONES main building. There are totally four shipping bays inside the main building, two of which are mainly responsible for components transportation. The lifting devices in the shipping bays should be carefully selected based on the requirements of components, including their sizes, weights, shapes, activation status, shielding requirements, human escorts and transportation routes. Considering these requirements and the building information, five possible lifting devices are proposed, namely parallel ropes lift, heavy load storage and retrieval machine, rack and pinion lift, upside-down scissor lift as well as rigid chain lift. The optioneering method is applied to assess the different lifting devices with the help of weighted criteria. As a result, parallel ropes lift, heavy load storage and retrieval machine and rigid chain lift are assessed as the most appropriate lifting devices in the shipping bays for DONES main building. A market survey is carried out on these three kinds of lifting devices. At the end of this paper, the principle sketches of the rigid chain lift inside the shipping bay are shown including the transport platform. • In this article, the flow of materials and requirements on two shipping bays in the DONES main building is analyzed. • Five possible lifting devices in the shipping bays are assessed using optioneering method. • Market research is carried out based on the optioneering result. • Principle sketch of rigid chain lift in the shipping bay is shown in this article. [ABSTRACT FROM AUTHOR]

• IFMIF-DONES: A new plant for studying the effect of neutron irradiation on fusion materials. • First general overview of the IFMIF-DONES Central Instrumentation and Control Systems. • Definitions, functions and requirements of the Central Instrumentation and Control Systems. • Relationship between Central and Local Instrumentation and Control Systems. • Critical role of protection and safety systems. Purpose of this work is to describe the Central Instrumentation and Control Systems for the International Fusion Materials Irradiation Facility-DEMO Oriented NEutron Source. A functional definition of the main systems is given, together with a general overview of the current status of the Central Instrumentation and Control Systems and the differences with respect to the corresponding system developed during the previous phases. The overall architecture of the Central Instrumentation and Control Systems (definitions, functions and requirements), the identification of subsystems and equipment, the control system design guidelines, and the Control Room requirements, are here described. Moreover, the Local Instrumentation and Control Subsystems is defined together with its relationship with the Central Instrumentation and Control Systems. [ABSTRACT FROM AUTHOR]

In the framework of the EU fusion roadmap implementing activities, an accelerator-based Li(d,xn) neutron source called DONES (Demo-Oriented early NEutron Source) is being designed within the EUROfusion Work Package Early Neutron Source as an essential irradiation facility for testing candidate materials for DEMO reactor and future fusion power plants. DONES will employ a high speed liquid lithium jet struck by a 125 mA, 40 MeV deuteron beam to generate the intense neutron flux used to irradiate the material samples up to the desired level of displacement damage (˜10 dpa/fpy for iron in 0.3 l) and He production rates (˜10-13 appm He/dpa). In order to rapidly achieve a sound and stable design, a new configuration of the DONES target system based on the so-called integral concept has been proposed as reference solution in place of the former baseline design that envisaged a target assembly endowed with a replaceable back-plate, being the latter solution not yet fully qualified and thus not readily implementable. Moreover, following the outcomes of detailed dedicated analyses taking into account different aspects, the design of several components (Quench Tank, Lithium inlet pipe, Vacuum Chamber, etc.) has been changed. In this paper, a brief description of the current design of the DONES Target System is presented including all the above-mentioned aspects, showing the capability of the system to fulfil the prescribed requirements. [ABSTRACT FROM AUTHOR]

Helium flows at low pressure (3 bar) are used to cool the specimen capsules and the structure of the neutron irradiated High Flux Test Module (HFTM) of the DEMO-Oriented Neutron Source (DONES). The flow path includes inlet and outlet ducts with large cross sections, but also mini-channels with gap widths less than 1 mm, where a high velocity low Reynolds number flow influences the temperature of the irradiated specimens. The aim of the study was the achievement of thermal requirements to the HFTM. The large span of Reynolds numbers from laminar to fully turbulent is a significant challenge for the simulation of the complete HFTM. Several turbulence models were tested using experimental results obtained in the ITHEX (IFMIF Thermal-Hydraulic Experiment) experimental facility. Reynolds Stress (RSM) and k-ω Shear Stress Transport (SST) models are able to reproduce the heat transfer within the Reynolds number range between 4500 and 10,000. Simulations show that in case of 100% nuclear heating conditions the prescribed temperature of specimen can be achieved by justification of electrical power and variation of helium mass flow rate for each HFTM compartment. [ABSTRACT FROM AUTHOR]

A maintainable test cell (TC) concept, which targets replacing TC key components in case of damages, for the IFMIF-DONES (International Fusion Materials Irradiation Facility – Demo Oriented NEutron Source) facility is proposed to facilitate the maintenance of key containment and biological shielding components, i.e. the liner and the surrounding concrete walls. Unlike the current TC reference design which features permanent liner and concrete shielding walls, the new proposal decouples the components which suffer relative high failure possibilities from the ones which can stay as permanent construction structures. The former ones, that are expected to be replaced in case of damage, include removable sections of the liner and part of the biological shielding materials. Fundamental mechanical solution of this configuration is briefly described, and technical feasibilities are preliminarily analyzed for the aspects of independent liner enclosure structure, maintenance scenarios using remote handling systems, etc. [ABSTRACT FROM AUTHOR]

• Deterministic Accident Analysis for DONES licensing are performed with MELCOR fusion version. • Lithium Loop and Accelerator models are developed for relevant scenarios. • Candidate safety systems, requirements and metrics under control are identified. • First scenario: beam shutdown and margin to lithium disappearance are addressed. • Second scenario: fast isolation valve and water reaching the target are addressed. Safety assessment is a key issue for the licensing of DONES facility, the DEMO-Oriented Neutron Source. A first phase of the safety assessment includes Failure Mode Analyses of systems to identify postulated initiating events (PIEs), while deterministic accident analyses are lately performed to estimate source terms in radiological hazards. In addition, the deterministic analyses are also the basis to identify safety class structures, systems and components, and to establish the operational range of system parameters as well as the actuation of the protection system. In this paper two accident scenarios, previously identified as PIEs, are explored with the fusion version of the MELCOR 1.8.6 code. A loss of flow (LOFA) in the lithium loop due to the trip of the electromagnetic pump and a loss of vacuum (LOVA) in the accelerator beam duct due to containment rupture have been studied to provide a preliminary estimation of the available actuation time for detection and mitigation systems with a particular focus on the beam shutdown system and isolation of the vacuum duct. [ABSTRACT FROM AUTHOR]

Highlights • Thermomechanical analysis of the new DONES Target Assembly layout has been performed to support its Preliminary Engineering Design. • Study was conducted with a numerical approach based on the Finite Element Method, adopting the Abaqus code. • Thermal calculations have shown results in line with expected design values. • Assessment of thermomechanical results allowed to check their compliance with concerned criteria of SDC-IC design code. Abstract The design of the Demo Oriented NEutron Source (DONES) is the main objective of the Work Package Early Neutron Source (WPENS) of EUROfusion Power Plant Physics and Technology (PPPT) programme. DONES is an IFMIF-based neutron source with the goal of testing and qualifying candidate materials to be used in DEMO and future fusion power plants. In the framework of these activities, a research campaign has been carried out at the University of Palermo, in close cooperation with ENEA labs, in order to assess the thermomechanical performances of the DONES target system, endowed with an integrated Target Assembly (TA) when it undergoes the thermomechanical loads typical of its nominal operating scenario. The effects on TA behaviour of two possible different configurations for the accelerator beam foot-print have been investigated, considering an entire (20 × 5 cm2) or a halved (10 × 5 cm2) beam foot-print area with respect to that of IFMIF. The study has been carried out following a theoretical-numerical approach, based on the Finite Element Method (FEM), and adopting the qualified ABAQUS v. 6.14 commercial FEM code. The obtained thermomechanical results have been assessed in order to check whether the BP deformation field is such to prevent the contact of the BP itself with the High Flux Test Module, as well as to verify their compliance with the design criteria foreseen for the structural material. To this purpose, a stress linearization procedure has been performed along the most critical paths located within the BP, in order to check the fulfilment of the rules prescribed by the ITER structural design code SDC-IC. The obtained results are herewith presented and critically discussed. [ABSTRACT FROM AUTHOR]

Highlights • First assessment of the vacuum performance of the IFMIF/DONES beamline subsystems. • No degradation of the vacuum performance by metal layer deposition was found. • The pressure profiles are determined by the beam losses in the respective subsystem. • The pressure profiles of the different subsystems are nearly independent from each other. Abstract Simulations of the gas flow inside the IFMIF-DONES vacuum system were performed with Molflow+. The IFMIF-DONES model is based on the last IFMIF/EVEDA design and of the LIPAc accelerator, which is being built for testing IFMIF accelerator components. Both, LIPAc and IFMIF-DONES share the same type of accelerator subsystems. The model was prepared for simulation by adding different sets of boundary conditions for the pumping of deuterium and hydrogen originating from beam losses and outgassing, respectively. A model of the lithium target was set up to study the lithium condensation at beamline components. The simulations of metal layer deposition in the vacuum system show no degradation of the vacuum performance. The simulations of the gas pumping show pressure profiles which are mainly determined by the beam losses in this subsystem. In general, the pressure profiles of the different subsystems are nearly independent from each other due to the small apertures installed between the subsystems. [ABSTRACT FROM AUTHOR]

The International Fusion Materials Irradiation Facility-DEMO Oriented NEutron Source (IFMIF-DONES) is an accelerator-based neutron source that generates high-energy neutrons via stripping processes by focusing a high-energy deuteron beam on a fast-flowing liquid lithium jet. The neutrons produced are used for the irradiation of materials foreseen in DEMO, thus providing relevant data for the design and licensing of the future fusion reactor. The complexity of such a plant is managed by a central control system that guarantees the safe supervision and control of all operations. This paper summarizes the most recent developments in the design of the IFMIF-DONES plant's Central Instrumentation and Control Systems (CICS) after the completion of the preliminary design phase. In particular, the architecture of two of the main CICS systems (namely, MPS and SCS) is described in detail, focussing on the specific design choices recently proposed. For each system, the current status of design is presented, as well as the existing and future plans for their integration in a unique control framework. [ABSTRACT FROM AUTHOR]

DONES is planned to operate on a continuous basis with only two beam stop periods per year for maintenance. The planned operational availability is 70 %, which calls for a carefully analyzed preventive maintenance. The purpose of the research is to propose a realistic and comprehensive logistics and maintenance plan. All the maintenance activities are included in a Maintenance Matrix based on the Plant Breakdown Structure of the project. This is the basis for the creation of a maintenance plan that will lead to a Work Schedule. Special mention within this matrix will be given to those Maintenance operations that must be included in order to comply with regulation. The need of replacement of components impose some requirements on the dimensions of architectural features of the main building such as doors, airlocks, corridors and shipping bays. To enable these replacements, the flow of materials has been developed and analyzed by an intralogistics simulation with AnyLogic. The results of this simulation lead to modifications on either the building or the components such that the replacements are feasible. The periodic replacement of an activated component has been analyzed using FMEA methodology resulting in proposals for the plant equipment designers as well as the remote handling equipment designers. Virtual reality simulations are used for a staged approach to the maintenance operation. The simulation of the HEBT scraper helped to define in detail each step or the maintenance operation. This tool has proven to be very useful to prompt changes in both the plant equipment design and the remote handling equipment. Also, the procedure of the operation itself can be refined and optimized. The conclusion of the research activities is the contribution to the definition of the building, plant equipment and achievement of the target availability. [ABSTRACT FROM AUTHOR]

The quench tank (QT) location in the test cell is an open issue for IFMIF-DONES (International Fusion Material Irradiation Facility- DEMO Oriented NEutron Source) design. Neutronics assessments have been carried out on two QT location options. A parametric study of the neutron streaming in the lithium chute shows a quasi-linear dependence of the neutron flux on the void thickness. For both options, activation calculations at key locations of the QT system indicate that the contact dose rate is higher than the hands-on dose limit over the whole maintenance period. In addition, the shutdown dose rates in the lithium facility room after 1-day shutdown exceed the hands-on dose limit in different levels. Therefore, remote handling is required for the maintenances of the QT in both considered locations. [ABSTRACT FROM AUTHOR]

The test cell (TC) in IFMIF-DONES (International Fusion Material Irradiation Facility – Demo Oriented NEutron Source) is the meeting area of the three major systems (test systems, lithium systems, and accelerator systems) to host the irradiation test module, lithium target assembly and the end section of the accelerator line. Although the design of the TC, to a large extent, inherits that of the reference IFMIF-EVEDA (Engineering Validation and Engineering Design Activities) TC, design justifications are required to solve the existing major open issues such as cavitation of the lithium flow, activation and maintainability of key components, and etc. In this paper, these major open issues of the reference TC layout are addressed and a TC reconfiguration proposal, featuring arranging the lithium quench tank inside the TC, is introduced. The two concepts are investigated, analyzed, and compared on the aspects of lithium flow stability, tritium generation rate, key component maintenance scenarios, irradiation shielding, and in-TC components arrangement. [ABSTRACT FROM AUTHOR]

IFMIF is considered as one of the main pillars in the international fusion program. Its double deuteron beam 125 mA each will produce enough rate of damage behind the lithium target to make available in a few years information on materials damage at DEMO relevant doses. Furthermore the stripping reaction D-Li will produce in Fe-based materials under study a production of He and H similar to those expected in fusion reactor. DONES (DEMO Oriented Neutron Source) has been conceived as a simplified IFMIF-like plant to provide in a reduced time scale and with a reduced budget – both compared to IFMIF- the basic information on materials damage. In this work, radiation conditions behind the irradiation module, the so-called High Flux Test Module (HFTM), are analyzed with a double objective. First objective is to assess the impact of the second irradiation module on the material irradiation effects in the HFTM due to its potential use as optimization tool for the damage dose and gas production in the specimens. Second objective is to assess on the potential use of that volume for irradiation of additional specimens beyond the HFTM. Then, neutron transport calculations have been performed in order to evaluate the impact on the irradiation effects on the HFTM and to determine the radiation level in the experimental samples of the new module. [ABSTRACT FROM AUTHOR]

• An Object-Oriented modelling approach for dynamic simulation. • Development of the model for the DONES Parallel Kinematic Manipulator (PKM). • Simulation of the robots, including the main non-linear effects due to backlashes and static friction. • Development of a preliminary control strategy. This paper describes the modeling and simulation activities performed, within the EUROfusion framework, to support the engineering design and the development of the control system of the DONES Parallel Kinematic Manipulator (PKM), a 6-DoF parallel robot part of the Remote Handling System of the DONES facility. The main tasks of the PKM are the planned annual replacement of the Target Assembly and the High Flux Test Module, two of the crucial and most activated components of DONES. The PKM model, developed using the Modelica object-oriented language, is able to simulate the dynamics of the entire robots, including the main non-linear effects due to backlashes and static friction. The simulator is employed to support the preliminary design of the control system, based on an independent-joint approach with dual-loop cascade-PID logic. Simulations are then conducted to assess robot performances in terms of resolution, accuracy, repeatability and generated forces. [ABSTRACT FROM AUTHOR]

• Hydraulic CFD analysis was carried out showing pressure drop of 2.9-3.4 kPa. • Solution time was measured for Single Precision and Dual Precision (DP) solvers. • 8 turbulence models were tested with k-ω BSL giving the fastest solution. • Single Precision solver was sufficient, solution time was reduce by 3.6-5.5. • Sufficient number of iterations for a correct solution was found to be 100. The International Fusion Materials Irradiation Facility – Demo Oriented Neutron Source (IFMIF-DONES) will allow accelerated material testing in fusion-like conditions, up to the doses above the expected lifetime. To successfully irradiate the samples in the High Flux Test Module (HFTM) an extensive start-up phase is needed to confirm the irradiation parameters as well as the conditions inside HFTM. STUMM (Start-Up Monitoring Module) is designed exactly for that purpose and will be operated during the commissioning phase of IFMIF-DONES. The outer part of STUMM resembles HFTM, but inside is equipped with measuring systems: active detectors and Rabbit Systems tightly arranged in the Container. The flow of helium gas used for cooling was analyzed in Ansys Fluent. A pressure drop of 2.9 kPa and 3.4 kPa was found for the two possible flow directions. 8 turbulence models were tested: Spalart-Allmaras, Standard k-ε, RNG k-ε, Realizable k-ε, Standard k-ω, Baseline k-ω, SST k-ω and the Reynolds Stress Model. Out of them, only the Standard k-ε mode did not converge and all the other models gave a correct result. The solution time was analyzed for both the Single Precision and Dual Precision solvers. The Single Precision solver was 3.6-5.5 faster. Analysis of the solution residuals, outlet velocity, and pressure drop showed that both solvers gave almost identical results, therefore the Single Precision solver is sufficient to obtain a correct solution and only 100 iterations are required. [ABSTRACT FROM AUTHOR]

• IFMIF-DONES is an accelerator-based DEMO-relevant neutron source for understanding the material behavior under neutron bombardment. • As the overall design is going on, we present here the current status of the design of the central instrumentation and control systems. • The main updates on data management including the EPICS control framework is pointed out. • General rules and criteria for the design and implementation of the human-machine interface system are outlined. • The most recent timing system solutions based on a three-layer distribution network to deliver time at each element of the plant are here briefly proposed. This work presents the current status of the design of Central Instrumentation and Control Systems for the IFMIF-DONES plant. IFMIF-DONES is the International Fusion Materials Irradiation Facility-DEMO Oriented NEutron Source, an accelerator-based neutron source producing a high-energy deuterons beam focused on a fast flowing liquid lithium jet to generate high-energy neutrons via stripping reactions. The intensity and irradiation volume is suitable to generate material irradiation data for design, licensing, construction and safe operation of the DEMO fusion reactor. After a general overview of the current status of the design of the overall architecture, a particular attention is given to the data management including the EPICS control framework, the general rules and criteria for the design and implementation of the HMI system, and the timing system solution composed of a three-layer distribution network to deliver time at each element of the plant that implements an optimal trade-off between timing performance and cost. Eventually, the next design steps and future work are outlined. [ABSTRACT FROM AUTHOR]

• Integration of all necessary diagnostics devices for beam characterization to allow an adequate monitoring of the beam dynamics requirements of IFMIF-DONES. • Fast Isolation Valve integrated to prevent water ingress in the Target and avoid exothermic reaction with the Lithium curtain. • Large Replaceable Units approach that allow fast replacement of modules reducing the DONES facility downtime during maintenance. • Remote Handling compatible design of accelerator devices with features to provide quick maintenance operations. The High Energy Beam Transport (HEBT) line components maintenance are to be conducted during twice yearly shutdown "beam off" periods, one 3-day shutdown and the main "beam off" shutdown period (annual preventive maintenance), which includes the necessary cooling and warming time, all totalling 20 days. Due to the radiation doses calculated and its subsequent radiation zone classification, technically challenging maintenance activities will need to be performed in the Accelerator Systems (AS) and particularly in the HEBT section located inside Target Interface Room (TIR). Thus, all HEBT components inside TIR must be designed to be maintained and replaced by Remote Handling (RH). In order to fulfil the RH requirements, a modularity approach intends to divide HEBT line section into independent large replacement units (LRUs), with localized interfaces. Splitting this section in three modules allows, first, the identification of faulty components more easily and secondly, reduces time needed for their replacement. In addition, the design of these modules has been performed to comply with beam dynamics, vacuum, building, RAMI and positioning requirements established for this section of the HEBT. As a result of the work done, the conclusions concerning the whole design process are summarized at the end of the paper. [ABSTRACT FROM AUTHOR]

• The pre-heating of the DONES Target Assembly mock-up has been investigated using the Abaqus FEM code. • A campaign of steady-state analyses has been carried out to select an optimal configuration for the electrical heaters. • Results obtained from detailed transient analysis partially confirmed results obtained from steady-state calculation. • The selected configuration will be adopted for the execution of the experimental campaign. Within the activities promoted by the EUROfusion consortium in support of the design and construction of the DEMO Oriented NEutron Source (DONES), a mock-up of its Target Assembly (TA), based on the configuration with a "bayonet" Back-Plate (BP) and available at ENEA Brasimone labs, is being adopted for the execution of experimental activities aiming at the validation of specific aspects of the target design. Despite the "integral"-TA concept is the current reference, experimental tests concerning the TA pre-heating phase are not significantly affected by the TA concept and are still representative even though conducted on the bayonet-TA concept. Indeed, the main objective of the pre-heating phase is to raise the TA temperature up to a value close to that of the lithium flow in nominal condition (250 °C). In particular, one of the main concerns is to keep the BP at a temperature higher than 200 °C to avoid possible local lithium freezing. In order to support the afore-mentioned tests, a numerical research campaign has been launched by ENEA Brasimone in collaboration with the University of Palermo with the goal of determining an optimal design of the electrical heaters, both in terms of temperature set-points and geometrical layout. To this purpose, several configurations have been assessed following a theoretical-computational approach based on the Finite Element Method (FEM) and adopting the Abaqus FEM code. In a first phase, different electric heater layouts were assessed by means of steady state thermal analyses. Once the most promising scenario was selected, a detailed thermal transient analysis was carried out. An iterative procedure, based on the analysis of the maximum temperature achieved within the mock-up most critical components, was followed in order to determine the duty cycle of the electric heaters. The obtained numerical results are herewith reported and critically discussed. [ABSTRACT FROM AUTHOR]

• IFMIF-DONES: an accelerator-based irradiation facility for nuclear fusion materials. • Solid-state (SS) technology applied to the RF System for DONES accelerator. • Modular RF System: RF Stations as a complete, compact, and independent module. • RF Station: latest LDMOS technology and advanced resonant cavity combiner. • Innovative RF System: world-class efficiency, availability, and maintainability. The IFMIF-DONES accelerator cavities require around 5.7 MW of continuous RF power at 175 MHz to deliver a 125 mA and 40 MeV deuteron beam at the lithium target. The IFMIF-DONES RF System is composed of 56 RF Stations able to provide up to 200 kW RF power at 175 MHz in CW, delivering a grand total of 7.4 MW. Such a massive system requires an ambitious approach to be able to comply with the accelerator requirements with a high efficiency and a high availability. The newest advancements in the field of RF systems for accelerators, which are already implemented independently in some facilities, are integrated for the first time in a single system from the early design phases. The result of this approach is the RF Station, which is a totally independent and compact RF module containing all the components needed to feed, control, and protect the accelerator cavities. The amplification technology chosen is the Laterally-Diffused Metal-Oxide Semiconductor (LDMOS) transistor, providing a good efficiency and high robustness. The proposed RF power combination of up to 160 transistors is based on resonant cavity combiner, allowing a single-step combination that highly reduces the losses with respect to more traditional corporate combining schemes. In this proposal, the RF generation relies on a fully digital Low-Level RF (LLRF) providing accurate amplitude/phase control and high flexibility to implement all the required functions for a proper cavity operation. The RF Station has been designed maximizing the modularity and the reliability. In order to achieve the required modularity, the LDMOS transistors have been grouped in Amplifier Modules (AMDs) containing four of them but keeping independent outputs. Furthermore, the AC/DC power converters have also been grouped in modules feeding a common DC bus. The RF Station will have redundant modules to be able to operate properly in any condition, even with some of them failed. This innovative proposal for the IFMIF-DONES RF System design and detailed information on the RF Stations architecture are presented in this paper. [ABSTRACT FROM AUTHOR]

• D1S methodology is proposed to be applied to material activation induced by light ion. • The new methodology is implemented in the D1SUNED code. • Results show a good convergence between the proposed method and reference calculation. One of the main radiation sources in nuclear facilities, which cause exposure of workers conducting maintenance activities, is the decay of radioactive nuclides. The determination of these radiation fields usually requires both radiation transport and activation calculations. The Direct-one-Step methodology allows obtaining response functions associated to the residual activity with a single Monte Carlo transport calculation. This methodology has been widely used in the analysis of nuclear fusion installations like ITER, JET or DEMO, proving to be a very efficient tool for Shutdown Dose Rate calculations. Yet, this methodology has only been applied when the material activation is due to the interaction with a neutron flux. Since, typically, in particle accelerators the D1S assumptions are met, it is proposed in this work to apply the D1S methodology to material activation induced by light ions interactions, namely: protons and deuterons. This methodology has been implemented in the D1SUNED code. In order to show its performance, the D1SUNED has been used to calculate the SDR in the LIPAc geometry, resulting in a good convergence with a reference calculation. [ABSTRACT FROM AUTHOR]

• Modular transportation concept developed feasible for transportation tasks in DONES. • Flexible transportation concept regarding changes in building layout and components. • Finite element analysis for standardized steel pallet. • Qualitative cost analysis of transfer alternatives. The qualification of materials to be used in the future DEMOnstration power plant (DEMO) is the main task of the DEMO Oriented Neutron Source facility (DONES). Over the next decades, experiments will be executed to analyze the reaction of in-vessel materials for DEMO which are exposed to neutrons of high energy. An efficient execution of experiments requires a steady maintenance and replacement of experiment-relevant equipment and machinery. In turn, the replacement requires a transportation concept for these components. This paper presents a solution for the transportation of heterogeneous components taking into account the different dimensions, geometries and weights. A modular transportation concept is developed that solves the transportation problem for all components with only one type of transfer device, a standardized pallet – which functions as an interface between the transfer device and components – and individual support structures. Moreover, the feasibility of the pallet to withstand the occurring loads is demonstrated by a Finite Element analysis. It is shown that compared to conventional solutions with many different transfer devices and load carriers, the modular concept enables a more cost-efficient and more flexible transportation. [ABSTRACT FROM AUTHOR]

• One challenging aspect on the development of DONES is the purity of the lithium. • An online sensor based on the PAV technique is proposed for H-isotopes monitoring. • The design consists of a capillary tube made of a Pd/Ag membrane spirally rolled. • An experimental facility is designed to demonstrate the feasibility of the monitor. • Theoretical simulations have been carried out using the EcosimPro platform. DONES (Demo Oriented Neutron Source) consists of an irradiation facility based in the nuclear stripping reactions that occur when one energetic deuteron beam impinges on a liquid lithium target flowing along an open channel. Since impurities enhance the erosion/corrosion effect, one of the challenging aspects on the development of the neutron source is the purity of the lithium. One group of impurities to be controlled are hydrogen isotopes in which the control of tritium as part of the produced impurities is mandatory due to its radiological risk. R&D activities are being performed for the development of different kinds of hydrogen sensors since there is no availability of commercial online monitors that could work under the lithium environment. As an extrapolation from other fusion applications, an online sensor based on the permeation against vacuum technique is proposed in this paper. The sensor design consists of a capillary tube made of a Pd/Ag membrane whose inner volume is subjected to vacuum promoting the H-isotopes permeation from the liquid. The vacuum line is connected to a mass spectrometer for the isotope detection. In addition, an experimental facility has been designed to experimentally demonstrate the feasibility of this monitor. It is made of a two-vessels system for lithium melting and H-isotopes detection. Furthermore, theoretical simulations have been carried out using the EcosimPro platform. Results show the expected behaviour of the sensor working under static conditions in the facility. [ABSTRACT FROM AUTHOR]

• The thermal-hydraulic behaviour of the DONES primary heat removal system has been studied using the RELAP5-3D code. • A parametric study was performed to assess the influence of the pump trip and beam shut-down delay on loop performances. • Results highlighted that the loop can work safely if the beam shut-down system works properly. • Results obtained are in line with those carried out adopting a different system code (MELCOR). The development of a neutron source able to reproduce the irradiation conditions typical of a nuclear fusion reactor, in order to test candidate structural materials, is the main goal of the Work Package Early Neutron Source (WPENS) of the EUROfusion action. This source, named Demo Oriented NEutron Source (DONES), is a facility where neutrons are produced by means of D-Li interactions. More in detail, a beam of 125 mA deuterium ions at the energy of 40 MeV strikes a lithium jet flowing in a purposely shaped channel in order to obtain an intense and stable neutron flux for the irradiation of material samples. In the framework of these activities, safety analyses are a key aspect in the DONES design and development. Among the postulated initiating events identified during the preliminary Failure Mode Analysis, the Loss of Flow Accident (LOFA) in the Primary Heat Removal System of the lithium loop, due to a trip of the electro-magnetic pump, is one of the most severe. In fact, the loss of lithium flow, combined with the failed stop of the accelerator, could lead to the destruction of the lithium flow channel in correspondence of the component named Back-Plate. For this reason, it has been chosen to investigate the LOFA adopting the deterministic system code RELAP5-3D. Results, obtained from this analysis, are critically discussed and compared with those obtained by a similar calculation carried out with MELCOR 1.8.6 code, in order to assess the RELAP5-3D capability of describing systems adopting lithium as working fluid. [ABSTRACT FROM AUTHOR]

• Helium flow within a heated mini-channels has been analysed using Helium experiments conducted in KIT. • Numerical simulations have been performed for low Reynolds number (Re=4000-10000) helium flows. • Four turbulence models, RSM, k-ε, k-ω SST and V2F were tested. • RSM and SST models are appropriate numerical tools for the heat transfer analysis of HFTM of the IFMIF-DONES. Helium flow at low pressure (0.3 MPa) is used to cool the specimen capsules and the structure of the neutron irradiated High Flux Test Module (HFTM) of the IFMIF-DONES (International Fusion Materials Irradiation Facility- DEMO Oriented NEutron Source). The flow path includes mini-channels with gap-widths less than 1 mm where a high velocity low Reynolds number helium flow is used as cooling medium. The large span of Reynolds numbers from laminar to fully turbulent is a significant challenge for the simulation of the complete HFTM. Four turbulence models, the Reynolds Stress transport (RSM); the k-ε (KE) model; the k-ω Shear-Stress-Transport (SST) model and the V2F model were tested using experiments conducted in Karlsruhe Institute of Technology (KIT). Numerical simulations have been performed for low Reynolds number (Re = 4000–10000) helium flows in a heated mini-channels. The RSM model provides the best heat transfer prediction for the full range of Reynolds numbers. KE and V2F models are not suitable for the simulation of the transitional flows. The accuracy of the SST model can be increased by variation of the time scale limiter coefficient. RSM and SST turbulence models can be considered as appropriate numerical tools for the heat transfer analysis of HFTM. [ABSTRACT FROM AUTHOR]

• Exploratory lithium fire analysis performed with Fire Dynamic Simulator code for DONES lithium loop system. • Conservative assumptions made for burner, considering lowest observed ignition temperature and full combustion with oxygen. • Fire spreading risk in the sampling room, accessible for the workers during the DONES normal operation, appears negligible. • A parametric analysis on released lithium inventory was performed in second accident occurring in lithium loop room. • In worst case liner not jeopardized, fire confined to EMP pit while pressure increases up to a peak of 86 kPa in the room. The exploitation of Nuclear Fusion energy in power plants will require the development and qualification of materials able to withstand outstanding neutronic loads for which no operating experience is currently available. Therefore, a Demo-Oriented early NEutron Source (DONES) facility for material irradiation is currently being designed within EUROfusion programme aimed at the production of neutrons with fusion relevant spectrum and fluence by means of D – Li stripping reactions occurring between a deuteron beam impacting a stable liquid lithium flowing film implementing the target. The Lithium System (LS) in DONES shall provide circulation of liquid lithium with suitable thermal-hydraulic characteristics and assure impurity control and heat removal. Given the hazard constituted by liquid lithium inventory and the potential risk of reactions with air eventually resulting into fire events, a preliminary evaluation of the modality of occurrence and evolution of such abnormal events in LS has been performed. In particular, two events have been selected for fire analysis. The first event considers a failure of off-line sampler equipment with water getting in contact with sampled lithium inventory. The initiating event is a failure in the glove box containing the off-line sampler. An air ingress occurs in the glovebox and a break of the Li flask is hypothesized at the same time. The second event assumes a leak at the outlet of the electromagnetic pump with loss of Lithium from the Li pipe in Heat Rejection System in LS room. Simultaneous air ingress is hypothesized as well in LS room (normally filled with inert argon). Fire loads were initially identified for the selected events and the room models developed considering dimensions, lithium inventory and fire compartment assumed to coincide with room limits. The ignition of lithium in contact with air occurs at liquid lithium operating temperature as reported in most conservative observations in literature and lithium fires were simulated as heat flux associated to lithium – air reactions rates observed in literature. A model for both events was implemented in Fire Dynamic Simulator (FDS) code to evaluate fire dynamics and a sensitivity analysis was performed on relevant inventories in the lithium loop area to investigate possible consequences. [ABSTRACT FROM AUTHOR]

• Preliminary design of the HEBT of the DONES accelerator is described. • Requirements considered for the design has been included. • Beam dynamics, diagnostics and vacuum studies are explained. • Remote handling and radioprotection studies are described. • The feasibility of a HEBT design fulfilling all the requirements is demonstrated. IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is currently being developed in the frame of the EUROfusion Early Neutron Source work package (WPENS) and will be an installation for fusion material testing, that will generate a flux of neutrons of 1018 m−2s−1 with a broad peak at 14 MeV by Li(d,xn) nuclear reactions thanks to a 40 MeV deuteron beam colliding on a liquid Li flow. The accelerator system is in charge of providing such high energy deuterons in order to produce the expected neutron flux. The High Energy Beam Transport line (HEBT) is the last subsystem of the accelerator and its main functions are to guide the deuteron beam towards the Lithium target and to shape it by the use of magnetic elements to the reference beam footprint at the Lithium Target. The present work summarizes the current status of the HEBT design, including beam dynamics, vacuum, radioprotection, diagnostics and remote handling studies performed, along with the layout and integration of the line. [ABSTRACT FROM AUTHOR]

• Functional and radiological requirements for HEBT Beam Dump Shielding are described. • Radiological analysis of Beam Dump Shielding is detailed for its two operational conditions. • Materials and dimensions for the Beam Dump Shielding conceptual design are explained. • Two Beam Dump Shielding configuration approaches have been studied and compared. • Benefits and drawbacks for each configuration proposed have been identified. IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is currently being developed in the frame of the EUROfusion Early Neutron Source work package (WPENS). It will be an installation for fusion material testing, that will generate a flux of neutrons of 1018 m−2s−1 with a broad peak at 14 MeV by Li(d,xn) nuclear reactions thanks to a deuteron beam colliding on a liquid Li flow. The accelerator system is in charge of providing such high energy deuterons in order to produce the neutron flux expected. The objective of the Beam Dump, part of the High Energy Beam Transport Line (HEBT), is to stop the pulsed beam at low duty cycle during DONES accelerator commissioning and start-up phases. The present work explains the radiological design of the beam dump shielding and two different configuration approaches for the materialization of the design. The radiological design considers maintenance and operation, and it was done together with the building walls dimensioning so that the combined radiation attenuation by the local shield and the building leads to dose rates in the different rooms that satisfy the requirements. Activation of the materials in the HEBT line, originated by the leakage of neutrons through the beam dump entrance is evaluated and an ad-hoc solution is proposed for its minimization. Regarding the mechanical design, in the first configuration, the shielding is split into two halves horizontally, the upper-half requiring external lifting capabilities for its commission and maintenance. The second approach consists in a vertical splitting into two halves, which are self-moveable, avoiding the needs of external lifting capabilities for the remote handling of the shielding. [ABSTRACT FROM AUTHOR]