Abstract: The EU DEMO fusion reactor has been conceived to deliver net electricity. Therefore, it must be equipped with a Balance of Plant (BoP) system aimed at removing fusion-generated heat power and transforming it into electrical power. Different BoP architectures are currently under investigation within the EUROfusion consortium, in order to meet needs and constraints of the in-vessel systems, with particular regard to the different blanket concepts.In this regard, the BoP system involving helium cooled in-vessel components has been considered in this work, meaning that the design of the DEMO reactor endowed with the Helium Cooled Pebble Bed breeding blanket (HCPB BB) has been taken into account. Specifically, the Indirect Coupling Design (ICD) HCPB BoP variant has been assessed in this work, as it is the reference configuration selected for the Conceptual Design Phase of DEMO. It foresees an Intermediate Heat Transfer system (IHTS), aimed at decoupling the BB- Primary Heat Transfer System (PHTS) from the power conversion system. Therefore, in the present work thermal and structural numerical analysis in support of the design of the DEMO HCPB IHTS are presented. In particular, the pipe stress analysis of the whole IHTS is first presented, highlighting pros and cons of the current piping layout and proposing potential design improvements. Then, a detailed 3D thermal and structural assessment of the IHTS main Heat Exchanger is reported, in order to show its soundness against the prescribed thermal and structural design criteria.The models, the assumptions, the considered loading scenarios as well as the obtained results are reported and critically discussed, highlighting their impact on the advancements of the DEMO HCPB BoP system design towards the conceptual stage.

Keywords: 3D FEM analysis | BoP system | EU DEMO | HCPB | IHTS | Pipe stress analysis

Abstract: Nowadays, modern manufacturing industries still rely on the expertise and manual dexterity of highly skilled operators. In this context, Mixed Reality (MR) technologies are emerging as promising solutions for contextualized task guidance to support operators during complex activities. However, their effective adoption in production environments is still limited by the lack of ergonomic evidence regarding their impact on operators’ well-being, usability, and interaction sustainability. This study investigates whether different interaction modalities with holographic instructional content influence the ergonomic suitability of a MR-based task guidance system for wire harnessing, developed in collaboration with Leonardo S.p.A. A between-subjects experimental design was adopted, involving 16 industrial workers randomly assigned to two groups: gaze and gesture interaction (Group A, n = 8), and gaze and voice interaction (Group B, n = 8). Ergonomic evaluation included both physical and cognitive aspects, assessed respectively through the Simulator Sickness Questionnaire (SSQ) and a composite usability index (UI) based on ISO 9241-11, integrating efficiency, effectiveness, and satisfaction. Results suggest comparable usability levels between the two interaction modalities (UIA = 0.683; UIB = 0.667). Gesture interaction was perceived as slightly more supportive of operational efficiency, whereas voice interaction was associated with lower cybersickness severity (mean TSA = 331.5; TSB = 196.1). Overall, the findings suggest that no single interaction modality universally outperforms the other, but rather that ergonomic suitability depends on the balance between physical workload, cognitive demands, and task characteristics. These results highlight the importance of human-centered ergonomic evaluations in the design of sustainable MR assistance systems for industrial environments.

Keywords: interaction modality | mixed reality | task guidance | wire harness

Abstract: Training for confined-space operations presents significant challenges due to safety risks, limited accessibility, and the complexity of reproducing realistic conditions. Within this context, immersive technologies such as Head-Mounted Display Virtual Reality (HMD-VR) offer a promising alternative for procedural training. This study evaluates the effectiveness of a hands-free, bimanual HMD-VR training system for confined-space operations as an alternative to physical training when access to real environments is constrained. Two HMD-VR configurations were investigated and compared with a physical training condition using a shared multi-step procedural scenario. Training outcomes were assessed across repeated executions and through a real-world evaluation, focusing on procedural performance and cognitive demand. Results show that all groups achieved significant improvements in performance over repeated executions, with reductions in completion time and error rate. Importantly, no statistically significant differences were observed between groups during the final real-world evaluation, and non-inferiority analyses confirmed that HMD-VR training did not result in performance outcomes worse than those achieved through physical training within predefined operational margins. Similarly, no significant differences emerged in either EEG-derived Cognitive Load (CL) or subjective workload at the final execution, despite a reduction in perceived workload over time. Analysis of subjective immersive experience revealed consistently high levels of presence and engagement across HMD-VR conditions, with no significant differences between configurations. However, spatial presence and perceived realism decreased over repeated exposure, suggesting an adaptation effect rather than a continuous increase in immersion. Overall, the findings indicate that, under the controlled conditions of this study, HMD-VR training enables real-world procedural execution and cognitive demand profiles comparable to those observed following physical training. These results support the potential of HMD-VR as a viable approach for novice procedural training in confined-space operations, particularly in contexts where traditional training is limited by safety, cost, or accessibility constraints.

Keywords: cognitive load | confined-space operations | EEG | experimental evaluation | HMD-VR training | performance evaluation | presence | procedural preparation | virtual reality

Abstract: The qualification of in-vessel components for a fusion power plant requires a test environment with a high flux of 14 MeV neutrons over a sufficiently large surface and volume. Performance testing and qualification of the complex design and technologies of fusion nuclear components is needed, in particular that of the tritium breeding blanket (BB). Testing in relevant conditions over a relevant time will also allow gaining the necessary confidence regarding the build-up and control of tritium inventories inside the BB, which will be an important radioactive source. An option of such a volumetric neutron source (VNS) is a beam-driven tokamak. A feasibility study of the main machine components and associated plant systems is described in this article. The machine has a major radius of 2.53 m, a single-null divertor configuration, and four tangential 120 keV beamlines that generate a fusion power of approximately 30 MW and provide current drive for a steady-state plasma scenario. The plasma is small with a minor radius of a = 0.55 m to maximize the neutron wall load, up to 0.5 MW/m², similar to what is targeted in ITER. Approximately 25 m² are available for blanket testing including 4 port plugs, which offer flexibility regarding the test module operating conditions and the implementation of instrumentation. Given the small plasma, much of the tokamak's volume is made up by the neutron shielding structures that are similarly sized as in ITER. To reduce the construction risk, ITER-like concepts were adopted for many components. In some cases, however, lessons learned from ITER led to the development of customized or innovative concepts. Due to the modest fusion power the plasma will burn <1 kg of tritium per year, which can be provided from external sources.

Keywords: Breeding blanket testing | Demo | Remote maintenance | Tokamak | VNS | Volumetric neutron source

Abstract: Digitalization represents a strategic enabler of innovation in industrial processes, particularly within complex and safety-critical domains. In the transition toward Industry 4.0, Augmented Reality (AR) demonstrates considerable potential to reshape work organization by enhancing efficiency and ensuring higher product quality. AR technologies can provide operators with context-aware instructions, interactive visual guidance, and improved operational control during cognitive and technically demanding tasks, such as electrical wiring assembly in the aerospace sector. To investigate the actual potential of video see-through devices, a dedicated AR application was developed for Meta Quest 3. The case study encompassed the digitization of technical documentation, the integration of three-dimensional models, and the design of an interactive User Interface (UI). The Usability of the application and its impact on Cognitive Load (CL) were assessed through controlled laboratory experiments involving two groups: one employing Meta Quest 3 and the other relying on conventional paper-based documentation. The results provide empirical evidence on the practical relevance and limitations of video see-through AR in supporting assembly operations. Specifically, the study revealed that the video see-through mode of Meta Quest 3 presents certain limitations and imposes a higher CL on users, although it also elicited high levels of user satisfaction regarding the use of AR technology. These results underscore the necessity of further optimizing AR hardware and interaction design to mitigate cognitive demands, while confirming the promising role of AR in advancing industrial training and assembly processes.

Keywords: Assistive technologies | Augmented reality | Ergonomics | Human factor | Usability assessment | Video see-through

Abstract: The present work focuses on the use of Immersive Virtual Reality (IVR) to train users by immersing them in safe and controlled Virtual Environment (VE) and enabling them to learn by doing. Particular attention is given to adaptive VR-training systems that are capable of dynamically adjusting the training experience based on user’s performance and cognitive state. Considering this, a new methodology for such systems is proposed, that is crafted on the Cognitive Theory of Multimedia Learning (CTML). This methodology aims to help instructors to understand how to adapt VR-training systems to users during their experience in VEs, leading to effective Learning Outcomes and avoiding a high Cognitive Load (CL). This human factor plays a critical role in mediating the relationship between Presence, Immersion, and Learning Outcomes, as the VE generates a CL to users. To have a deeper understanding, factors influencing CL in VEs are presented and relative solutions are proposed. It is our understanding that adaptive VR-training systems, their design, architecture, and attributes, can pave the way to new research directions and that the new methodology presented in this paper will be supportive.

Keywords: Adaptive VR-training system | Cognitive load | Human factors | Learning outcomes | Virtual reality

Abstract: In the framework of the activities coordinated by the EUROfusion consortium, the Water thermal-HYDRAulic (W-HYDRA) experimental platform is being built at the ENEA Brasimone Research Centre in order to support the development of the Water-Cooled Lead Lithium (WCLL) Breeding Blanket (BB). In particular, this infrastructure will make possible the installation and testing of prototypical mock-ups under relevant working conditions, such as the First Wall (FW), the manifold and the Steam Generator (SG). Moreover, it will represent an integral test facility for the investigation of phenomena characteristic of WCLL BB concept, such as the PbLi/water interaction. Finally, the collection of data coming from the different planned experimental campaigns will allow to qualify and validate numerical models and codes currently adopted for the design of components, as well as for the modelling of complex phenomena typical of the WCLL BB. In order to come to a definitive design of the different facilities constituting the experimental platform, several design analyses assessing the thermal, hydraulic and structural performances of the different facilities and components are necessary. The paper reports a highlight of the W-HYDRA platform with a general description of the facilities. Some of the most relevant design studies carried out so far are reported as well, highlighting their impact on the evolution of the design.

Keywords: breeding blanket | DEMO | experimental platform | WCLL

Abstract: An overview is presented of the progress since 2021 in the construction and scientific programme preparation of the Divertor Tokamak Test (DTT) facility. Licensing for building construction has been granted at the end of 2021. Licensing for Cat. A radiologic source has been also granted in 2022. The construction of the toroidal field magnet system is progressing. The prototype of the 170 GHz gyrotron has been produced and it is now under test on the FALCON facility. The design of the vacuum vessel, the poloidal field coils and the civil infrastructures has been completed. The shape of the first DTT divertor has been agreed with EUROfusion to test different plasma and exhaust scenarios: single null, double null, X-divertor and negative triangularity plasmas. A detailed research plan is being elaborated with the involvement of the EUROfusion laboratories.

Keywords: divertor | exhaust | plasma scenarios

Abstract: Factory acceptance test is the inspection of equipment and components at the supplier’s premises before delivery or final inspection. However, this control can represent a considerable cost for the customer, especially when the manufacturer’s company is geographically far from the customer one and inspections must be frequent. In this paper, the authors present a framework to support the factory acceptance test based on augmented reality (AR) techniques and model-based definition aimed at dimensional checks that does not require the physical presence of the customer at the supplier's premises. The supplier must be previously equipped with an automatic measuring machine. Once the component under inspection is placed inside the machine, this reads the type and the position of the features to be measured along with the related specification limits directly from the annotated 3D model of the component. The results are automatically transmitted to the customer’s site. Through a tablet, the supplier, guided by the customer, reads the results of the measures directly on the measured object through augmented or mixed reality techniques. Any out-of-specification dimension can be remeasured in real time with the customer’s remote assistance using traditional measurement techniques. The proposed architecture, at an advanced stage of experimentation, is discussed with reference to an industrial case study proposed and using an entry level commercial 3D scanner.

Keywords: Augmented reality | Dimensional inspection | Factory acceptance test | Metrology

Abstract: This work is focused on the development of a “serious game”, i.e., a software with no playful purpose adopted to train and verify the skills of users to improve safety in the workplace. Particular attention has been given to the accidents that occur during typical operations done in factory sites, e.g., driving forklifts. Firstly, the different types of “serious games” already available on the market have been analyzed to identify the best way to carry on tests and simulations by means of virtual, mixed, and augmented reality. Afterward, once the best solution has been identified, the Unity development environment has been considered to define a standard that could also be used for future projects. So, the result is the development of a powerful editor of the scene, in which the user can program all the components adjusting the game to the tasks to be performed by the worker, the tools, the environment and the targets. So, an upgradeable “parametric path” has been created, which will be followed by the forklift, realizing a new game and test environment for the worker. Then, modular components have been conceived to contemplate the future developments of the project, including a graphic editor: these will lead to a software that can be easily modified according to the customer’s requests.

Keywords: Occupational safety | Serious games | Virtual reality

Abstract: Recent R&D activities in nuclear fusion have identified the DEMO reactor as the ITER successor, aiming at demonstrating the technical feasibility of fusion plants, along with their commercial exploitation. However, the pulsed operation of the machine causes an “unconventional” operation of the system, posing unique challenges to the functional feasibility of the steam generator, for which it is necessary to define and qualify a reference configuration for DEMO. In order to facilitate the transitions between different operational regimes, the Once Through Steam Generator (OTSG) is considered to be a suitable choice for the DEMO primary heat transfer systems, being characterized by lower thermal inertia with respect to the most common U-tube steam generators. In this framework, the ENEA has undertaken construction of the STEAM facility at Brasimone R.C., aiming at characterizing the behavior of the DEMO OTSG and related water coolant systems in steady-state and transient conditions. A dedicated OTSG mock-up has been conceived and designed, adopting a scaling procedure, keeping the height 1:1 of the DEMO OTSGs. The conceptual design has been supported by RELAP5/Mod3.3 thermal-hydraulic calculations. CFD and FEM codes have been used for fluid-dynamic analyses and mechanical stress analyses, respectively, in specific parts of the component.

Keywords: DEMO | experimental installation | once through steam generator (OTSG) | RELAP5 | STEAM facility | water technologies

Abstract: In the framework of the EUROfusion Horizon Europe Programme, ENEA and its linked third parties are in charge of the conceptual design of the steam generators belonging to EU DEMO WCLL Breeding Blanket Primary Heat Transfer Systems (BB PHTSs). In particular, in 2021, design activities and supporting numerical simulations were carried out in order to achieve a feasible and robust preliminary concept design of the Once Through Steam Generators (OTSGs), selected as reference technology for the DEMO Balance of Plant at the end of the Horizon 2020 Programme. The design of these components is very challenging. In fact, the steam generators have to deliver the thermal power removed from the two principal blanket subsystems, i.e., the First Wall (FW) and the Breeding Zone (BZ), to the Power Conversion System (PCS) for its conversion into electricity, operating under plasma pulsed regime and staying in dwell period at a very low power level (decay power). Consequently, the OTSG stability and control represent a key point for these systems’ operability and the success of a DEMO BoP configuration with direct coupling between the BB PHTS and the PCS. In this paper, the authors reported and critically discussed the FW and BZ steam generators’ thermal-hydraulic and mechanical design, the developed 3D CAD models, as well as the main results of the stability analyses and the control strategy to be adopted.

Keywords: DEMO | fusion technologies | power plant | steam generator | WCLL balance of plant

Abstract: Helping workers return to work as soon as safe and functionally possible after a workplace injury is a subject of major interest in the context of occupational health. For this, we developed a serious game for construction industry aimed at training workers about the proper use of an electric pallet truck inside a simulated environment. The simulation platform is endowed with a physical control interface and three training missions were implemented. During the game experience, the player is also asked to answer to some questions about the possible risks and the related protection measures. The results of preliminary experiments about the usability of our training framework are here reported and discussed.

Keywords: learning | product interface design | serious games | usability assessment | virtual training

Abstract: Within the EUROfusion roadmap for the technological development of the European-DEMOnstration (EU-DEMO) reactor, a key point has been identified in the discontinuous operation (pulse-dwell-pulse) of the machine. Water Cooled Lithium Lead (WCLL) Breeding Blanket (BB) Primary Heat Transfer Systems (PHTSs) adopt technology and components commonly used in nuclear fission power plants, whose performances could be negatively affected by the above mentioned pulsation, as well as by low-load operation in the dwell phase. This makes mandatory a full assessment of the functional feasibility of such components through accurate design and validation. For this purpose, ENEA Experimental Engineering Division at Brasimone R.C. aims at realizing STEAM, a water operated facility forming part of the multipurpose experimental infrastructure Water cooled lithium lead -thermal-HYDRAulic (W-HYDRA), conceived to investigate the water technologies applied to the DEMO BB and Balance of Plant systems and components. The experimental validation has the two main objectives of reproducing the DEMO operational phases by means of steady-state and transient tests, as well as performing dedicated tests on the steam generator aiming at demonstrating its ability to perform as intended during the power phases of the machine. STEAM is mainly composed of primary and secondary water systems reproducing the thermodynamic conditions of the DEMO WCLL BB PHTS and power conversion system, respectively. The significance of the STEAM facility resides in its capacity to amass experimental data relevant for the advancement of fusion-related technologies. This capability is attributable to the comprehensive array of instruments with which the facility will be equipped and whose strategic location is described in this work. The operational phases of the STEAM facility at different power levels are presented, according to the requirements of the experiments. Furthermore, a preliminary analysis for the definition of the control strategy for the OTSG mock-up was performed. In particular, two different control strategies were identified and tested, both keeping the primary mass flow constant and regulating the feedwater mass flow to follow a temperature set-point in the primary loop. The obtained numerical results yielded preliminary feedback on the regulation capability of the DEMO steam generator mock-up during pulsed operation, showing that no relevant overtemperature jeopardized the facility integrity, thanks to the high system responsivity to rapid load variations.

Keywords: DEMO components assessment | DEMO water technologies | experimental installation | RELAP5 thermal-hydraulic analysis | STEAM facility

Abstract: The Pre-Concept Design (PCD) of the Balance of Plant (BoP) systems of the EU-DEMO power plant is described in this paper for both breeding blanket (BB) concepts under assessment, namely the Water Cooled Lithium Lead (WCLL) BB and the Helium Cooled Pebble Bed (HCPB) BB. Moreover, the results of a preliminary evaluation of a number of BoP variants are discussed. This paper outlines the steps of the BoP design development, highlighting the project objectives and the strategy for their achievement under the very challenging requirements which include, among others, the intermittent nature of the DEMO plasma heat source. The main achievements during the PCD Phase will be reported together with the development plan for the Concept Design (CD) Phase to reach a mature (feasible) BoP concept for DEMO.

Keywords: Balance of plant | DEMO | HCPB BB | Power conversion system | Steam generator | WCLL BB

Abstract: DEMO will be a fusion power plant demonstrating the integration into the grid architecture of an electric utility grid. The design of the power conversion chain is of particular importance, as it must adequately account for the specifics of nuclear fusion on the generation side and ensure compatibility with the electric utility grid at all times. One of the special challenges the foreseen pulsed operation, which affects the operation of the entire heat transport chain. This requires a time-dependant analysis of different concept design approaches to ensure proof of reliable operation and efficiency to obtain nuclear licensing. Several architectures of Balance of Plant were conceived and developed during the DEMO Pre-Concept Design Phase in order to suit needs and constraints of the in-vessel systems, with particular regard to the different blanket concepts. At this early design stage, emphasis was given to the achievement of robust solutions for all essential Balance of Plant systems, which have chiefly to ensure feasible and flexible operation modes during the main DEMO operating phases – Pulse, Dwell and ramp-up/down – and to adsorb and compensate for potential fusion power fluctuations during plasma flat-top. Although some criticalities, requiring further design improvements were identified, these preliminary assessments showed that the investigated cooling system architectures have the capability to restore nominal conditions after any of the abovementioned cases and that the overall availability could meet the DEMO top-level requirements. This paper describes the results of the studies on the tokamak coolant and Power Conversion System (PCS) options and critically highlights the aspects that require further work.

Keywords: Balance of plant | DEMO | HCPB | PHTS | WCLL

Abstract: One of the most challenging objectives of the European research concerning nuclear fusion technology, promoted by the EUROfusion consortium, is to bring stellarator-type nuclear fusion devices to maturity. To this purpose, studies on a large HELIcal-axis advanced stellarator (HELIAS), extrapolated from Wendelstein 7-X and based on a 5-fold symmetry (HELIAS 5-B), are currently ongoing. The HELIAS 5-B stellarator reactor will be endowed with a breeding blanket (BB) system to allow for the self-sustainability of the nuclear fusion reaction and make it suitable for electricity generation. In this paper, we present the first ever heterogeneous mechanical design and the preliminary structural assessment of a bean-shaped ring of a HELIAS 5-B BB sector. The proposed mechanical design, which is based on the helium-cooled pebble bed (HCPB) BB concept and developed according to the “sandwich” architecture, foresees an actively cooled segment box connected to a back-supporting structure equipped with manifolds. The internal region (breeding zone) is reinforced by actively cooled steel plates. The proposed heterogeneous design was checked against nominal loads and an in-box loss of coolant accidental scenario, which is a typical design driver for BBs. The assessment has been performed according to the RCC-MRx structural design code. Our results are herewith presented and critically discussed, focusing on the potential follow-up of the HELIAS 5-B HCPB BB design.

Keywords: breeding blanket | FEM analysis | HELIAS | Stellarator | structural design | thermo-mechanics

Abstract: The realization of nuclear fusion reaction as energy source is under investigation, among the scientific community, through the design and development of tokamak reactors. Among the several experiments worldwide, the ITER project is the major international experiment and it involves several research institutes from several countries. In such a project, a Systems Engineering (SE) approach is requested to organize and manage the design due to its highly integrated design, the safety requirements related to nuclear aspects and the complex procurement scheme. The SE discipline focuses the attention on the requirements which are crucial for every successful project, defining what the stakeholders want from a potential new system, namely what the system must do to satisfy stakeholders need. Correctly stating WHAT is needed for the system, it is possible to obtain its conceptual design (HOW) as much as possible complying the requirements. The incorrect definition of requirements often leads to the failing of a project. Stakeholders’ needs are written in Natural Language that is generally ambiguous, imprecise, incomplete and redundant. Their transformation into SMART requirements is crucial to avoid design failure. However, it requires a great expertise, unless a specific procedure is assessed. To this end, this work presents a specific procedure based on “like-mind” processes to make systematic the SMART requirements definition and assessment from stakeholders needs. The procedure is based on a demand/response framework and it is developed to obtain ITER requirements. However, it can be easily extended to every project using its own specifications. A specific case study on ITER Remote Handling is presented in this paper as example of the conceived requirements transformation procedure.

Keywords: ITER tokamak | Requirements engineering | SMART requirements | Systems engineering

Abstract: An early attention to the layout of both plant site and its buildings is essential in a complex plant under preliminary design as DEMO in order to meet the assigned targets, namely i) the licensing requirements ii) a good availability in delivery electricity to the grid. The layout definition has to follow several criteria that become more complex and stringent for nuclear buildings, e.g. functional, maintenance, fire protection, safety, human factors, shielding, and remote handling. The criterion As Low As Reasonable Achievable, with respect to the dose to the staff, has to be applied in design, operation, maintenance and decommissioning phases. The tokamak building, where several complex systems have to converge to the torus to create and control the plasma, to take out its energy and to produce and extract tritium, provides the second and ultimate confinement barrier between the environment and the hazardous and radioactive materials present inside that might be mobilised, in case of accident, by the high energetic fluids stored in DEMO systems. The layout criteria are focused on avoiding any challenge to the safety functions: e.g. no common mode failures of the safety classified systems for all reference design basis events. Furthermore the safety classified equipment have to maintain their safety function all over the plant life in such challenging environmental conditions; an accurate layout might allow the qualification possible, making milder the environment, e.g. defining adequate shielding and areas where radiation dose, magnetic field and accidental environmental conditions are reasonable for sensible equipment. The experience of NPPs and ITER is also recognized as the basis of such design criteria for DEMO. The paper will outline the main design basis events and the layout criteria presenting some applications for the tokamak building that reflect the recent progress of the DEMO design.

Keywords: DEMO | Layout criteria | Safety | Tokamak building

Abstract: The European Research Roadmap to the Realisation of Fusion Energy foresees that the DEMO reactor is going to succeed ITER in the pathway towards the exploitation of nuclear fusion, achieving long plasma operation time, demonstrating tritium self-sufficiency and producing net electric output on an industrial scale. Therefore, its design must be more oriented towards the Balance of Plant (BoP) than it is in ITER. Since the early pre-conceptual phase of the DEMO project, emphasis has been laid on identifying the main requirements affecting the overall architecture of the BoP. For instance, specific efforts and proper solutions have been envisaged to cope with the pulsed nature of the heat source. Furthermore, the current development of two blanket concepts calls for two separate BoP options to be conceived. This paper summarizes the main alternatives outlined at the end of DEMO pre-conceptual design phase for the BoP concepts based on both the Helium-Cooled Pebble Bed (HCPB) and Water-Cooled Lithium Lead (WCLL) Breeding Blanket (BB) technologies. Then, the assumed reference configurations of both the BoP concepts are described in detail, highlighting the main features and the most relevant engineering aspects. Attention will be focussed on technological challenges, integration constraints and other open issues, highlighting pros and cons of the chosen BoP options to be further investigated in the next design phase.

Keywords: Balance of plant | DEMO | HCPB | WCLL

Abstract: In the frame of the activities promoted and encouraged by the EUROfusion Power Plant Physics and Technology (PPPT) department aimed at developing the EU-DEMO fusion reactor, strong emphasis has been recently addressed to the whole Balance of Plant (BoP) which represents the set of systems devoted to convert the plasma generated thermal power into electricity and to deliver it to the grid. Among these systems, the Divertor Primary Heat Transfer Systems (PHTSs) are intended to feed coolant to the two main components of the Divertor assembly, namely the Plasma Facing Components (PFCs) and the Cassette Body (CB). Since the DEMO Divertor must withstand high heat flux loads together with a considerable neutron deposited power, very tight tolerances may be allowed to the coolant inlet conditions. Therefore, the design of reliable PHTSs is of the utmost importance towards the development of an EU-DEMO fusion reactor. Within this framework, a study has been jointly carried out by University of Palermo, Ansaldo Nucleare and CREATE to design the Ex-Vessel PHTSs of both the PFCs and the CB for a DEMO reactor equipped with a Helium Cooled Pebble Bed Breeding Blanket. The paper describes criteria and rationale followed with the aim to achieve simple PHTS designs based on the adoption of easy-to-manufacture main components avoiding too much extrapolation from the state-of-art technology. Results of preliminary thermal-hydraulic calculations carried out to size heat exchangers, pressurizers, piping and pumps are presented and critically discussed, with particular attention to those integration, safety and feasibility constraints that may deeply affect the design of such components. Finally, the evaluation of PHTS key parameters as total pumping power and coolant inventory is reported.

Keywords: Balance of plant | DEMO | Divertor | PHTS

Abstract: The Water Cooled Lithium Lead Test Blanket System (WCLL TBS) is one of the EU Test Blanket Systems candidate for being installed and operated in ITER. In view of its Conceptual Design Review by F4E and ITER Organization (IO), planned for mid-September 2020, several technical activities have been performed in the areas of WCLL TBS Ancillary Systems design. In this article the outcomes of the conceptual design phase of the four main Ancillary Systems of WCLL TBS, namely the Water Cooling System (WCS), the Coolant Purification System (CPS), the PbLi loop and the Tritium Extraction System (TES), are reported and critically discussed. In particular, for each Ancillary System hereafter are reported: i) a short design description, including the conceptual design of their main components together with their operative conditions under the so-called Normal Operational State (NOS), ii) the ESP-ESPN classification for their main components, and iii) their arrangement and integration in the assigned ITER areas (PC#16, Vertical Shaft, TCWS Vault, Galleries and Tritium Process Room).

Keywords: CPS | ITER | PbLi loop | TES | WCLL TBS | WCS

Abstract: Collaborative robotics, or Human-Robot Collaboration (HRC), is a challenging topic characterized by multidisciplinary approaches. Many researchers are facing this innovative manufacturing system studying several aspects such as task allocation, facility layout problem and timing. Above all, one of the most important issues in collaborative robotics is the wellbeing of the operator collaborating with the robot system during the different phases of the process. The added value of a collaborative workplace respect to the manual and automatic workplaces is strictly correlated to a safe and ergonomic interaction between the operator and the robot. Indeed, the combination of robot and operator skills lead to a higher level of accuracy and flexibility. Thus, assessing operator's working conditions requires the acquisition, eventually in real time, of relevant parameters such as posture, movements, and interactive tasks. This may require the adoption of existing metrics proposed by standard evaluation guidelines, as well as the introduction of new or modified prescription to consider the presence of the robot. The ergonomics analysis in collaborative robotics is evaluated by considering both physical and cognitive aspects of the operator during the interaction with the robot. The research work aims to carry out a scientific bibliometric literature review (BLR) about the ergonomics analysis of collaborative workplaces, and to identify methods and tools for the physical and cognitive ergonomics assessment that can be adopted in collaborative robotics. The search has been accomplished using the Scopus database by means of a set of key words specifically defined to investigate the ergonomics in the collaborative robotics. The review provides a sharp classification, a critical analysis of the most relevant contributions in this field so that emerging trends for future development can be defined and discussed.

Keywords: Bibliometric literature review (blr) | Cognitive ergonomics | Human-robot interaction (hri) | Humanrobot collaboration (hrc) | Physical ergonomics

Abstract: The present work has two main objectives: the realization of a Virtual Training system about assembly operations in two immersive virtual environments and the comparison between the features offered. The first solution proposed is the use of commercial software IC.IDO, produced by ESI Group. It is designed for applications throughout all the PLM, offering support both in the design and production phases, as well as after-sales assistance. At the opposition, the second solution proposed is the use of the Open-source software Unity. This graphics engine has found significant success in gaming field in the recent years, as it allows more flexibility to the developer for the implementation of the features but requires greater competence in terms of programming. The following paragraphs firstly address the path outlined from the collection of customer’s requirements to the virtual prototypes’ release, following the Systems Engineering approach. Secondly, a benchmark between IC.IDO and Unity’s features is illustrated to point out their main differences, strengths and weaknesses.

Abstract: The European DEMOnstration power plant (DEMO) is considered to be the nearest-term fusion reactor capable of producing several hundred MWs of net electricity, operating with a closed tritium fuel-cycle (achieving the tritium self-sufficiency), and qualifing technological solutions for a fusion power plant with different breeding blanket (BB) concepts that are under investigation. The BB is a key component for the development of the DEMO plant design and, in particular, of those systems having the responsibility to remove the plasma-generated thermal power and its conversion in the electrical energy. This study deals with the preliminary thermo-mechanical design of the heat exchangers and steam generator components. The design criteria and the main design analyses were discussed to achieve a simple but robust design. The proposed preliminary thermo-mechanical designs, both for heat exchangers and for steam generators, are considered feasible.

Keywords: Balance of plant (BoP) | DEMOnstration power plant (DEMO) | heat exchanger | steam generator | tube sheet

Abstract: This paper presents an innovative safety training method based on digital ergonomics simulations and serious games, which are games that focus on education. Digital ergonomics is intended to disseminate the culture of safety among workers, while serious games are used to train the operators on specific safety procedures and verify their skills. The results of the experimentation in a real industrial environment showed that, compared to the traditional training methodology, multimedia contents and quantitative ergonomic analyses improve the level of attention and the awareness of the workers about their own safety. However, serious games turned out to be promising training tools with regard to standard operating procedures that are usually difficult or dangerous to simulate in a real working scenario without stopping production. Practitioner summary: Digital ergonomics and serious games are used to disseminate the culture of safety among the workers and for safety training. Our results show that the proposed methodology improves the level of attention and provides a better feedback about the actual skills of the workers than the standard educational strategies. Abbreviations:.

Keywords: Digital humans | occupational safety | serious games | training methods

Abstract: Most occupational safety regulations and international standards recognize the importance of keeping a corporate document that set all the safety procedures prescribed for a certain workplace. However, experience show that, to be truly effective, any piece of information must be kept updated and correctly delivered to the right recipient. From this point of view, the possibility, given by modern technology, to receive, process and send information in real time using common smartphones is a great opportunity. The authors developed a solution for mobile devices, which is based on augmented reality technologies and indoor positioning algorithms, aimed at speeding up and simplifying the information flow among safety managers, workers and casual users about safety-related content. Safety managers can use it as a support tool for the preparation of the risk assessment documentation, on the workers' side, the same application acts as an informational tool providing safety-related content when and where needed through augmented reality technologies. Preliminary results from in situ testing show that augmented reality may be a powerful tool to improve the occupational safety.

Keywords: Augmented reality | Mobile technologies | Workplace safety

Abstract: Most occupational safety regulations and international standards recognize the importance of keeping a corporate document that set all the safety procedures prescribed for a certain workplace. However, experience show that, to be truly effective, any piece of information must be kept updated and correctly delivered to the right recipient. From this point of view, the possibility, given by modern technology, to receive, process and send information in real time using common smartphones is a great opportunity. The authors developed a solution for mobile devices, which is based on augmented reality technologies and indoor positioning algorithms, aimed at speeding up and simplifying the information flow among safety managers, workers and casual users about safety-related content. Safety managers can use it as a support tool for the preparation of the risk assessment documentation, on the workers’ side, the same application acts as an informational tool providing safety-related content when and where needed through augmented reality technologies. Preliminary results from in situ testing show that augmented reality may be a powerful tool to improve the occupational safety.

Keywords: Augmented reality | Mobile technologies | Workplace safety

Abstract: This research discusses the use of a systematic design method, the Iterative and Participative Axiomatic Design Process (IPADeP), for the early conceptual design stage of large-scale engineering systems. The involvement of multiple and competing requirements has imposed high challenges for achieving an affordable design of complex systems in a reasonable lead time. Systems Engineering (SE) focuses on how to design and manage complex systems over their life cycles. Both must begin by discovering the real problems that need to be resolved and identifying from the early stage of the design the main stakeholder requirements and customer needs. The Axiomatic Design (AD) methodology is widely recognized in the literature to efficiently support the design of complex systems from the early conceptual stage. IPADeP provides a systematic methodology for applying AD theory in the conceptual design of large-scale engineering systems, aiming to minimize the risks related to the uncertainty and incompleteness of requirements and to improve the collaboration of multi-disciplinary design teams. IPADeP has been adopted as design methodology in the pre-conceptual design stage of a subsystem of the DEMOnstration fusion power plant (DEMO): the divertor cassette body-to-vacuum vessel locking system. In this paper improvements in IPADeP are presented and its validity is discussed by presenting the application to the divertor system design.

Keywords: Axiomatic Design | Design methods | Systems Engineering | Tokamak design

Abstract: Unfortunately, the affiliation of one of the authors “Salvatore Gerbino” was incorrect in the original publication, and the correct version is updated here.

Abstract: This paper presents an interactive design method aimed at improving workplace health and safety. Human performances and anthropometric variability are carefully considered to make the workplace “robust” from a safety point of view. This topic is of increasing interest to industries that plan to make safer workplaces without renouncing to their productivity targets. A challenging issue concerns the evaluation of the effects of sources of anthropometric variability in the process by using just a small sample of real or digital humans. The adoption of a discretization technique helps to solve this problem and saving time and resources. Through real industrial case studies, the authors investigate the main ergonomic and safety issues faced during the development of both manual and human–robot hybrid workcells.

Keywords: Design methods | Digital human modelling | Human–robot interaction | Robust design | Virtual ergonomics | Virtual safety

Abstract: In this work we present the latest progresses (September 2018) in the conceptual design of the main containment structures of DTT fusion reactor. The previous DTT baseline design is revised in terms of structural materials and overall reactor shape. The major change involves the vacuum vessel, which now foresees a welded double-wall stainless steel structure. The basic design includes eighteen sectors, with novel ports configuration for remote maintenance systems, diagnostics and heating equipment. New supports are designed for the first wall, which is conveniently segmented in view of assembly and remote replacement. The cryostat of the machine is conceived as a single-wall cylindrical vessel reinforced by ribs. The cryostat base is also in charge of supporting the vacuum vessel and the magnets system. A preliminary FEA analysis confirms that the main mechanical structure might withstand the design loads, in particular the ones resulting from possible plasma disruptions.

Keywords: CAD | DTT | EU-DEMO | FEM | Fusion reactor | Structural analysis

Abstract: In the frame of the activities promoted and encouraged by the EURO-fusion Power Plant Physics and Technology (PPPT) department aimed at developing the EU-DEMO fusion reactor, strong emphasis has been recently posed to the whole Balance of Plant (BoP) which represents the set of systems devoted to convert the plasma generated thermal power into electricity and to deliver it to the grid. Among these systems, a very important role is played by the Breeding Blanket (BB) Primary Heat Transfer System (PHTS) as it is responsible to extract more than 80% of the fusion plasma power. In this framework, University of Palermo, Ansaldo Nucleare and CREATE have focused their work to improve thermal-hydraulic, safety and integration features of the Ex-Vessel PHTS for the Helium-Cooled Pebble Bed (HCPB) BB concept of DEMO. Starting from the outcomes obtained in 2016 that have allowed to highlight some criticalities which needed design changes, the paper describes progress and developments of the 2017 HCPB PHTS as well as the goals which have been achieved. The results of the research activity carried out show, in fact, i) an increase of the thermal-hydraulic performances, since a reduction in both total coolant inventory and total pressure drop has been respectively reached, ii) a potential improvement of the overall safety characteristics of the system. Nevertheless a critical assessment of these key parameters reveals that some issues are still open in terms of design integration and feasibility of the whole DEMO BoP for the helium-cooled blanket option, indicating that additional efforts are required to make this technology more attractive.

Keywords: Balance of plant | DEMO | HCPB | PHTS

Abstract: This paper focuses on the 3D CAD implementation of the pipework and the main equipment of the Primary Heat Transfer System of EU-DEMO fusion power plant. In particular, the systems related to the Helium-Cooled Pebble Bed Breeding Blanket option are considered here. During the pulse operation, the breeding blanket modules will be the main thermal power source; Divertor and the Vacuum Vessel will contribute in the definition of the total reactor power. All the In-Vessel generated power is rejected to the Power Conversion System through a molten salt Intermediate Heat Transport System. The latter is equipped with an Energy Storage System to allow for continuous operation also during the dwell time. The layout of the pipework considered the major design constraints, such as the reinforced concrete structures and the dimensions of the main pieces of equipment. The size of the pipes was selected based on operating pressure, temperature and allowable velocity. Results provide a first estimation of length and weight of the piping systems as well as their space occupancy. These data are useful to evaluate the coolant inventory, as well as the expected pressure drops and plant cost.

Keywords: EU-DEMO | Helium-Cooled Pebble Bed Breeding Blanket | ITER | Piping design | Primary heat transfer system

Abstract: The water-cooled lithium-lead breeding blanket is in the pre-conceptual design phase. It is a candidate option for European DEMO nuclear fusion reactor. This breeding blanket concept relies on the liquid lithium-lead as breeder-multiplier, pressurized water as coolant and EUROFER as structural material. Current design is based on DEMO 2017 specifications. Two separate water systems are in charge of cooling the first wall and the breeding zone: thermo-dynamic cycle is 295–328 °C at 15.5 MPa. The breeder enters and exits from the breeding zone at 330 °C. Cornerstones of the design are the single module segment approach and the water manifold between the breeding blanket box and the back supporting structure. This plate with a thickness of 100 mm supports the breeding blanket and is attached to the vacuum vessel. It is in charge to withstand the loads due to normal operation and selected postulated initiating events. Rationale and progresses of the design are presented and substantiated by engineering evaluations and analyses. Water and lithium lead manifolds are designed and integrated with the two consistent primary heat transport systems, based on a reliable pressurized water reactor operating experience, and six lithium lead systems. Open issues, areas of research and development needs are finally pointed out.

Keywords: Breeding blanket | DEMO | EUROfusion | WCLL

Abstract: This work focuses on an innovative training methodology based on the use of Virtual ergonomics and “serious games” in the field of occupational safety. Virtual Ergonomics was chosen as an effective and convincing tool for disseminating the culture of safety among the workers, while a “serious game” was developed to train operators on specific safety procedures and to verify their skills. The results of the experimentation in a real industrial case study showed that, compared to the traditional training methodology, multimedia contents and quantitative ergonomic analyses improve the level of attention and the awareness of the operators about their safety. On the other hand, Serious games turned out as promising tools to train the workers about safe operating procedures that are difficult to implement in a real working environment.

Keywords: Ergonomics | Occupational safety | Serious game | Virtual humans | Virtual reality

Abstract: The computerization of manufacturing is one of the major challenges of the so-called fourth industrial revolution or Industry 4.0. Virtualization of the smart factory should provide real-time vision, control and monitoring of production through interactive dashboards and synchronization of data coming from different factory functions. The latter characteristics are particularly difficult to implement when the manufacturing core relies on traditional manual labour rather than on automation, as in the case of manual assembly. Monitoring or even controlling the manual work in real-time is extremely difficult to put into practice. Therefore, realizing the principles of Industry 4.0 in manual or semi-automatic labour contexts means developing new production control systems that involve the worker in the monitoring process without negatively affecting the production times or the psychological status of the workers. In particular, the authors propose a computer-aided production control framework based upon multimedia manuals and smart completeness control systems that can be used to implement the principles of Industry 4.0 in manual or semi-automatic work environments. This technology has been successfully tested in laboratory on the basis of a real industrial case study. The response of the testers has been positive and the outcomes in terms of increased product quality are promising.

Keywords: Cyber-physical systems | Industry 4.0 | Interactive electronic technical manuals | Production monitoring | Smart manufacturing

Abstract: In Europe (EU), in the frame of the EUROfusion consortium activities, four Breeding Blanket (BB) concepts are being developed with the aim of fulfilling the performances required by a near-term fusion power demonstration plant (DEMO) in terms of tritium self-sufficiency and electricity production. The four blanket options cover a wide range of technological possibilities, as water and helium are considered as possible coolants and solid ceramic breeder in combination with beryllium and PbLi as tritium breeder and neutron multipliers. The strategy for the BB selection and operation has to account for the challenging schedule of the EU DEMO, the ambitious operational requirements of the BBs and the still large development needed to have a BB qualified and licensed for operating in DEMO. In parallel to the continuous design efforts on the four blanket concepts, their integration in-vessel and ex-vessel has started. On the one hand it has become clear that despite the numerous systems to be integrated in-vessel the protection of the blanket first wall has to be addressed with highest priority. On the other hand the ex-vessel interfaces and the requirements imposed by the blanket to the primary heat transfer system and to the PbLi loop components have a considerable impact on the whole DEMO Plant layout. The aim of this paper is: to present the strategy for the DEMO BB down selection and BB operation in DEMO; to describe the status of the design evolution of the four EU BB concepts; to provide an overview of the challenges of the in-vessel and ex-vessel integration of the main systems interfacing the BBs and describe their design status.

Keywords: Balance of plant | Breeding Blanket | In-vessel and ex-vessel components

Abstract: The Water-Cooled Lithium Lead breeding blanket is a candidate option for the realization of European DEMO power plant. One of the main functions of the breeding blanket is to recover the thermal power from the first wall and the breeding zone and to drive it to the Primary Heat Transfer System. Moreover, due to the DEMO pulsed operation, an Energy Storage System is foreseen in order to ensure thermal energy availability and reduce cycling loading during dwell time. The blanket design must interface with the Primary Heat Transfer System and the Intermediate Heat Transfer System in an integrated solution with the aim of delivering feasible power plant, with high conversion efficiency. A thermal-hydraulic model of the main components of the water cooled Primary Heat Transfer System is developed, using RELAP5 system code, to support the design and sizing. A RELAP5/Mod3.3 extended version has been set-up to implement PbLi and molten salt (HITEC) fluid proprieties, as well as the relevant heat transfer correlations. The results of the preliminary applications provide a comprehensive set of thermo-hydraulic parameters (i.e. coolant inventory, pressure drops), relevant for the assessment of the design integration.

Keywords: Breeding blanket | DEMO | PHTS | WCLL

Abstract: The water-cooled lithium-lead (PbLi) breeding blanket is one of the candidate systems considered for the implementation in the European Demonstration Power Plant (DEMO) nuclear fusion reactor. This concept employs PbLi liquid metal as tritium breeder and neutron multiplier, water pressurized at 15.5 MPa as the coolant, and EUROFER as the structural material. The current design is based on the single module segment approach and follows the requirements of the DEMO-2015 baseline design. The module is constituted by a basic toroidal-radial cell that is recursively repeated along the poloidal direction where the liquid metal flows along a radial-poloidal path. The heat generated by the fusion reactions is extracted by means of separate cooling systems for the breeding zone and the first wall. A back supporting structure is dedicated to withstand loads of the module during normal and off-normal operations. Water and PbLi manifolds are integrated with primary heat transport and tritium extraction systems. The status of the conceptual design is presented, critically discussing its rationale and main features as supported by neutronic, thermal-hydraulic, magneto-hydrodynamic, and thermo-mechanic analyses. Recent results are outlined, pointing out open issues and development needs.

Keywords: Breeding blanket (BB) | Demonstration Power Plant (DEMO) | fusion reactor design | liquid metal technology

Abstract: The use of Augmented Reality (AR) technologies is the new challenge of management models born under the “Industry 4.0” paradigm. The aim of the work is to evaluate the usability of two types of AR devices (tablet and see-through) employed in the training and information activities of workers according to the ISO/IEC 9126 and ISO 9241 standards. Starting from the state of the art, evaluating market and competitors and developing different concepts of interfaces, a dedicated application was programmed and, then, the usability of such devices for the professional figures involved was evaluated through experimental tests. Two reference scenarios were defined, the Department of Industrial Engineering of University of Naples Federico II and INAIL (National Institute for Insurance against Accidents at Work) laboratories, an user interface was designed and developed, as an aid in the drafting of the document for risk evaluation and subsequent training of workers. The activity is part of the IDEE Project (Interactive Design for Ergonomics), born by the collaboration between Joint Lab IDEAS and Contarp-INAIL-Regional Management for Campania. The data analysis allowed to evaluate the goodness of the devices and the degree of satisfaction in their use on the basis of the sample of users who conducted the tests. The use of AR devices produces better results than paperwork in terms of efficiency and effectiveness, but not all devices produce appreciable results in terms of user satisfaction. Although AR technologies are mature, the tasks need to be carefully defined to avoid rejection phenomena. The strong expectation, that they generate in potential users, risks to remain disappointed today for some usability limits found in currently available devices. It is necessary to start testing in pilot applications in various industrial fields in order to capture in time and adequately support this opportunity of innovation in Italy.

Keywords: Augmented reality | Risk assessment | Usability

Abstract: The water-cooled lithium–lead breeding blanket is a candidate option for the European Demonstration Power Plant (DEMO) nuclear fusion reactor. This breeding blanket concept relies on the liquid lithium–lead as breeder–multiplier, pressurized water as coolant, and EUROFER as structural material. The current design is based on DEMO 2015 specifications and represents the follow-up of the design developed in 2015. The single-module-segment approach is employed. This is constituted by a basic geometry repeated along the poloidal direction. The power is removed by means of radial–toroidal (i.e., horizontal) water cooling tubes in the breeding zone. The lithium–lead flows in a radial–poloidal direction. On the back of the segment, a 100-mm-thick plate is in charge of withstanding the loads due to normal operation and selected postulated initiating events. Water and lithium–lead manifolds are designed and integrated with a consistent primary heat transport system, based on a reliable pressurized water reactor operating experience, and the lithium–lead system. Rationale and features of the single-module-segment water-cooled lithium–lead breeding blanket design are discussed and supported by thermo-mechanic, thermo-hydraulic, and neutronic analyses. Preliminary integration with the primary heat transfer system, the energy storage system, and the balance of plant is briefly discussed. Open issues, areas of research, and development needs are finally pointed out. @EUROfusion Consortium*, 2017. *For more details see http://www.euro-fusionscipub.org/disclaimer-copyright.

Keywords: breeding blanket | DEMO | WCLL

Abstract: This paper describes the activity addressed to the conceptual design of the first wall and the main containment structures of DTT device. The work moved from the geometrical constraints imposed by the desired plasma shape and the configuration needed for the magnetic coils. Many other design constraints have been taken into account such as remote maintainability, space reservations for diagnostic and heating equipment, etc. The basic vessel design resulted in an all-welded single-wall toroidal structure made of 18 sectors. Proper supports have been designed for the first wall, which was conveniently segmented in view of remote maintenance. This provisional model allowed evaluating the electromagnetic loads on the metallic structure of the vacuum vessel resulting from the current quench due to a plasma disruption. After a FEA mechanical assessment, which was conducted according to ASME code, INCONEL® 625 has been provisionally selected as reference material for vacuum vessel. The design principles of the cryostat were chiefly based on cost minimization and functionality; thus it was conceived as a single-wall cylindrical vessel supported by a steel frame structure. The same structure will hold the vacuum vessel and the magnets.

Keywords: 3D CAD modeling | Conceptual design | Cryostat | FEM | First wall | Mechanical analysis | Vacuum vessel

Abstract: Water-cooled lithium-lead breeding blanket is considered a candidate option for European DEMO nuclear fusion reactor. ENEA and the linked third parties have proposed and are developing a multi-module blanket segment concept based on DEMO 2015 specifications. The layout of the module is based on horizontal (i.e. radial-toroidal) water-cooling tubes in the breeding zone, and on lithium lead flowing in radial-poloidal direction. This design choice is driven by the rationale to have a modular design, where a basic geometry is repeated along the poloidal direction. The modules are connected with a back supporting structure, designed to withstand thermal and mechanical loads due to normal operation and selected postulated accidents. Water and lithium lead manifolds are designed and integrated with a consistent primary heat transport system, based on a reliable pressurized water reactor operating experience, and the lithium lead system. Rationale and features of current status of water-cooled lithium-lead breeding blanket design are discussed and supported by thermo-mechanics, thermo-hydraulics and neutronics analyses. Open issues and areas of research and development needs are finally pointed out.

Keywords: Breeding blanket | DEMO | WCLL

Abstract: As indicated in the European Fusion Roadmap, the main objective of the Divertor Tokamak Test facility (DTT) is to explore alternative power exhaust solutions for DEMO so as to mitigate the risk that the conventional divertor based on detached conditions to be tested on the ITER device cannot be extrapolated to a fusion reactor. The issues to be investigated by DTT include: • demonstrate a heat exhaust system capable of withstanding the large load of DEMO in case of inadequate radiated power fraction;• close the gaps in the exhaust area that cannot be addressed by present devices;• demonstrate that the possible (alternative or complementary) solutions (e.g., advanced divertor configurations or liquid metals) can be integrated in a DEMO device. In this paper, we describe a proposal for such a DTT, presented by ENEA in collaboration with a European team of scientists. The selection of the DTT parameters (a major radius of 2.15 m, an aspect ratio of about 3, an elongation of 1.6-1.8, a toroidal field of 6 T, and a flat top of about 100 s) has been made according to the following specifications: • edge conditions as close as possible to DEMO in terms of dimensionless parameters;• flexibility to test a wide set of divertor concepts and techniques;• compatibility with bulk plasma performance.• an upper bound of 500 M€ for the investment costs. This paper illustrates this DTT proposal showing how the basic machine parameters and concept have been selected so as to make a significant step toward the accomplishment of the power exhaust mission.

Keywords: Design | Divertor | Tokamak devices

Abstract: The main goal of the Divertor Tokamak Test facility (DTT) is to explore alternative power exhaust solutions for DEMO. The principal objective is to mitigate the risk of a difficult extrapolation to fusion reactor of the conventional divertor based on detached conditions under test on ITER. The task includes several issues, as: (i) demonstrating a heat exhaust system capable of withstanding the large load of DEMO in case of inadequate radiated power fraction; (ii) closing the gaps in the exhaust area that cannot be addressed by present devices; (iii) demonstrating how the possible implemented solutions (e.g., advanced divertor configurations or liquid metals) can be integrated in a DEMO device. In view of these goals, the basic physical DTT parameters have been selected according to the following guidelines: (i) edge conditions as close as possible to DEMO in terms of dimensionless parameters; (ii) flexibility to test a wide set of divertor concepts and techniques; (iii) compatibility with bulk plasma performance; (iv) an upper bound of 500 M€ for the investment costs.

Abstract: Nowadays digital substitutes of human beings (digital humans), capable of interacting with digital mock-ups in Virtual Reality, are widely used in many fields of engineering (e.g. ergonomics, product design, maintenance, and training). Nevertheless, the animation process of digital humans is still a time-consuming task, and its accuracy and reliability strongly depend on the experience and the skills of the operator. This paper presents an innovative algorithm capable of significantly speeding up the animation process of digital humans, allowing the operator to focus only on the so-called "task-related control points". This approach allows also to easily conduct biomechanical analyses. The algorithm has been tested with reference to several application scenarios in Virtual Reality.

Keywords: Algorithm | Digital humans | Kinematics | Virtual reality

Abstract: This work explores the use of an industry-oriented digital human modelling tool for the estimation of the musculoskeletal loads corresponding to a simulated human activity. The error in using a static analysis tool for measuring articulations loads under not-static conditions is assessed with reference to an accurate dynamic model and data from real experiments. Results show that, for slow movements, static analysis tools provide good approximation of the actual loads affecting human musculoskeletal system during walking.

Keywords: Biomechanics | Dynamics | Gait analysis | Kinematics | Virtual simulation

Abstract: In parallel with the programme to optimize the operation with a conventional divertor based on detached conditions to be tested on the ITER device, a project has been launched to investigate alternative power exhaust solutions for DEMO, aimed at the definition and the design of a divertor tokamak test facility (DTT). The DTT project proposal refers to a set of parameters selected so as to have edge conditions as close as possible to DEMO, while remaining compatible with DEMO bulk plasma performance in terms of dimensionless parameters and given constraints. The paper illustrates the DTT project proposal, referring to a 6 MA plasma with a major radius of 2.15 m, an aspect ratio of about 3, an elongation of 1.6-1.8, and a toroidal field of 6 T. This selection will guarantee sufficient flexibility to test a wide set of divertor concepts and techniques to cope with large heat loads, including conventional tungsten divertors; liquid metal divertors; both conventional and advanced magnetic configurations (including single null, snow flake, quasi snow flake, X divertor, double null); internal coils for strike point sweeping and control of the width of the scrape-off layer in the divertor region; and radiation control. The Poloidal Field system is planned to provide a total flux swing of more than 35 Vs, compatible with a pulse length of more than 100 s. This is compatible with the mission of studying the power exhaust problem and is obtained using superconducting coils. Particular attention is dedicated to diagnostics and control issues, especially those relevant for plasma control in the divertor region, designed to be as compatible as possible with a DEMO-like environment. The construction is expected to last about seven years, and the selection of an Italian site would be compatible with a budget of 500 M.

Keywords: divertor | plasma facing components | tokamak

Abstract: This paper focuses on a preliminary structural analysis of the current concept design of DEMO vacuum vessel (VV). The VV structure is checked against a vertical load due to a Vertical Displacement Event in combination with the weight force of all components that the main vessel shall bear. Different configurations for the supports are considered. Results show that the greatest safety margins are reached when the tokamak is supported through the lower ports rather than the equatorial ports, though all analyzed configurations are compliant with RCC-MRx design rules.

Keywords: DEMO vacuum vessel | Elastoplastic analysis | Finite element method (FEM)

Abstract: This paper describes the development of a master model concept of the DEMO vacuum vessel (VV) conducted within the framework of the EUROfusion Consortium. Starting from the VV space envelope defined in the DEMO baseline design 2014, the layout of the VV structure was preliminarily defined according to the design criteria provided in RCC-MRx. A surface modelling technique was adopted and efficiently linked to the finite element (FE) code to simplify future FE analyses. In view of possible changes to shape and structure during the conceptual design activities, a parametric design approach allows incorporating modifications to the model efficiently.

Keywords: CAD-FEA associativity | Conceptual design | DEMO vacuum vessel | Surface modelling

Abstract: This paper investigates the thermal and fluid dynamic effects of a cold air jet generated by a Ranque-Hilsch vortex tube on the cutting tool of a milling machine. A simulation model that predicts the temperature field and the displacements of the tool due to the thermal effects was developed. Such a model can help to correct machining errors and improve cutting accuracy of air-cooled milling machines. Experimental results validated the model. Eventually, the post-processing of the computational fluid dynamics (CFD) data has been conducted in virtual reality.

Keywords: CFD analysis | Dry machining | Flux simulation | FSI method | Heat transfer | Machine tool | Ranque-Hilsch vortex tube | Thermo-energetic investigation | Tool | Virtual reality post-processing

Abstract: This paper describes a new motion analysis protocol for race-walking. The protocol has been tested under laboratory conditions on a real athlete of the Italian national race-walking team. The experimental setup included a motion capture system and a force platform to record both kinematic and dynamic aspects of the athletic action. Thus, any infringement of the rules can be detected, based on the measure of knee flexion-extension and the loss of ground contact. The biomechanical efficiency can be determined from the joint angles and the temporal components of gait. The results of experiments show that the protocol can be a valuable tool to assist athletes and trainers in improving race-walking technique.

Keywords: Biomechanics | Dynamics | Experimental protocol | Gait Analysis | Kinematics | Motion Capturing | Race-walking

Abstract: In view of the ITER conceptual design review, the design of the ancillary systems of the European test blanket systems presented in [1] has been updated and made consistent with the ITER requirements for the present design phase. Europe is developing two concepts of TBM, the helium cooled lithium lead (HCLL) and the helium cooled pebble bed (HCPB) one, having in common the cooling media, pressurized helium at 8 MPa [2]. TBS, namely helium cooling system (HCS), coolant purification system (CPS), lead lithium loop and tritium extraction/removal system (TES-TRS) have the purpose to cool down the TBM and to remove tritium to be driven to TEP from breeder and coolant. These systems are placed in port cell 16 (PC#16), chemical and volume control system (CVCS) area and tritium building. Starting from the pre-conceptual design developed in the past, more mature technical interfaces with the ITER facility have been consolidated and iterative design activities were performed to comply with design requirements/specifications requested by IO to conclude the conceptual design phase. In this paper the present status of design of the TBS is presented together with the preliminary integration in ITER areas.

Keywords: Breeding blanket | Integration in ITER | Tritium extraction and management

Abstract: This paper explores a possible integration of some ancillary systems of helium-cooled lithium lead (HCLL) and helium-cooled pebble-bed (HCPB) test blanket modules in ITER CVCS area. Computer-aided design and ergonomics simulation tools have been fundamental not only to define suitable routes for pipes, but also to quickly check for maintainability of equipment and in-line components. In particular, accessibility of equipment and systems has been investigated from the very first stages of the design using digital human models. In some cases, the digital simulations have resulted in changes in the initial space reservations.

Keywords: CAD | Design for maintainability | Digital human modeling | Piping layout design

Abstract: This paper focuses on a structured methodology that uses virtual reality (VR) and digital human modeling (DHM) to study maintenance procedures of industrial products. VR technologies help to highlight the most critical aspects of maintenance operations, while DHM tools allow detailing working sequences. Data coming from these analyses are then used to draw up a multimedia maintenance manual based on digital video animations, audio comments, explanatory images and written recommendations. Information is available to maintenance personnel directly on the working site through portable electronic devices. Further, web-based multimedia manuals can be updated on-line and help to shorten learning time and maintenance downtimes. © 2013 Springer-Verlag France.

Keywords: Design for maintainability | Digital human modelling | Multimedia maintenance manuals | Virtual design review

Abstract: The aim of the paper is to address an innovative methodology for assessing the usability of a product. This methodology is particularly suitable for designing products that provide their main functions through their control interfaces. In particular, this case study relates to the usability assessment of two control devices for a wheelchair-mounted robot manipulator to assist physically disabled people. The study focuses on defining a synthetic usability index on the basis of two currently used methods: the multi criteria decision analysis and the Saaty's analytic hierarchy process. Several virtual reality (VR)-based experiments have been conducted, set up in accordance with a cross-array experimental plan, that adequately caters for both control and noise factors. Quantitative measures and subjective user evaluations have been collected to maximize the effectiveness, the efficiency and the satisfaction perceived by users while using the product. Compared to the literature on the subject, the proposed approach provides both more flexibility in defining quantitative indexes and more adequate results, even when involving only a small sample of users in the participatory design session. The use of VR technologies for the collection of the experimental data has been essential in terms of safety, costs and repeatability of the tests, as well as of the robustness with respect to noise factors. © 2012 Springer-Verlag London Limited.

Keywords: Analytic hierarchy process (AHP) | Assistive robotics | Participatory design | Usability index | Virtual reality experiments

Abstract: An algorithm for both human-like motion generation and joint torques computation for digital humans is addressed in this paper. This goal has been achieved using techniques derived from robotics. In particular, the so-called augmented Jacobian has been used to solve the inverse kinematics problem with a single closed loop inverse kinematics algorithm. Furthermore, a position control for the center of mass of the kinematic chain, and for its projection on the support plane (center of pressure), has been implemented to achieve easy posture control. Thus, the inverse kinematics can be solved taking into account the static balance of the digital human. Moreover, the proposed algorithm allows simulating quite complex tasks, which involve the motion of the whole body, by means of only few task-related control points arbitrary located on the whole kinematic chain. The resulting movements are quite natural even for complex tasks as can be seen on the simulation experiments reported which show the effectiveness of the proposed approach. Finally, the joint torques can be computed thanks to the kinetostatics duality: the results are in accordance with biomechanical analyses. © 2011 Springer-Verlag.

Keywords: Digital humans | Human-like motion generation | Kinetostatic duality | Low-back biomechanical analysis | Multiple-point kinematic control | Posture control

Abstract: This work concerns the usability assessment of two control devices for a wheelchair-mounted robot manipulator aimed at assisting physical disabled people. The assessment of the usability is a crucial issue for the design of such products, since they communicate with their users not only through their shape, but especially through their control interfaces. In a first phase, the study focuses on defining a synthetic usability index on the basis of the methodologies currently in use. In a second phase, some experiments in Virtual Reality (VR) have been carried out. The use of VR technologies for the collection of the experimental data has been fundamental in terms of safety, costs and repeatability of the tests. Another important result has been the reduction of the sources of noise, thanks to preliminary simulations in VR and non-invasive questionnaires and interviews for capturing the subjective perceptions of users. Finally, it is worth noticing that the developed model may show its validity also in evaluating the usability of other products. Indeed, it provides a basis for a more extensive use of VR experiments for evaluating different design solutions in terms of global usability requirements. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Analytic Hierarchy Process (AHP) | Assistive robotics | Participatory design | Usability index | Virtual reality experiments

Abstract: The present paper deals with the manufacturing process of a railway carriage. In the first part of the paper, the authors focus on a "virtual railway factory" that uses a very innovative assembly cycle, if compared to the traditional manufacturing processes in the railway field. The case study refers to a railway carriage consisting of four modules, that are singularly set up of furnishings and other systems in dedicated workplaces. On one hand, the virtual simulation has highlighted several critical aspects to be improved, in order to achieve a greater feasibility and to reduce time and cost. On the other hand, the designers have been able to evaluate the movements of the parts and the assembly sequences of the components, by considering each geometric, functional and technological constraint and also some safety requirements. The second part of the paper deals with the simulation of the assembling operations and the analysis of tolerance chains, which have been performed through a Computer Aided Tolerancing system. In particular, the precision requirements have been also evaluated and we have compared the accumulation of dimensional and geometric deviations when using both rivets and traditional welds to fasten the modules. © 2009 Springer-Verlag.

Keywords: Computer Aided Tolerancing | Train design | Virtual manufacturing

Abstract: The design of solutions for robotic extenders of wheelchairs must take into account both objective and subjective metrics for everyday activities in human environments. Virtual Reality (VR) constitutes a useful tool to effectively test design ideas and to verify performance criteria. This paper presents the development of a simulation environment, where three different manipulators to be mounted on a commercially available wheelchair have been considered. Experimental results are discussed in a significant case study, based upon users' feedback. © The Eurographics Association 2008.

Keywords: Human robot interaction | Kinematics | Rehabilitation robotics | Virtual Reality

Abstract: In this paper, we describe a framework which helps designers visualize and verify the results of robotic work cell simulation in a Virtual Environment (VE). The system aims at significantly reducing production costs and error sources during manufacturing processes. The means to achieve these goals are the development of a prototypical VE for the support of robots planning tasks, reuse of animation events, and the implementation of customization tools for animation elements and their behavior. By using advanced Virtual Reality (VR) techniques, the system is also able to direct the focus of the observer to interesting events, objects and time-frames during robotic simulations in order to highlight the Human Robot Interaction within the manufacturing systems. © The Eurographics Association 2007.