Materials R&D for a timely DEMO: Key findings and recommendationsof the EU Roadmap Materials Assessment Group

The findings of the EU Fusion Programme’s ‘Materials Assessment Group’ (MAG), assessing readiness ofStructural, Plasma Facing (PF) and High Heat Flux (HHF) materials for DEMO, are discussed. These areincorporated into the EU Fusion Power Roadmap [1], with a decision to construct DEMO in the early2030s.The methodology uses project-based and systems-engineering approaches, the concept of TechnologyReadiness Levels, and considers lessons learned from Fission reactor material development. ‘Baseline’materials are identified for each DEMO role, and the DEMO mission risks analysed from the known lim-itations, or unknown properties, associated with each baseline material. R&D programmes to addressthese risks are developed. The DEMO assessed has a phase I with a ‘starter blanket’: the blanket mustwithstand @le;2 MW yr m−2fusion neutron flux (equivalent to ∼20 dpa front-wall steel damage). The base-line materials all have significant associated risks, so development of ‘Risk Mitigation Materials’ (RMM)is recommended. The R&D programme has parallel development of the baseline and RMM, up to ‘down-selection’ points to align with decisions on the DEMO blanket and divertor engineering definition. ITERlicensing experience is used to refine the issues for materials nuclear testing, and arguments are devel-oped to optimise scope of materials tests with fusion neutron (‘14 MeV’) spectra before DEMO designfinalisation. Some 14 MeV testing is still essential, and the Roadmap requires deployment of a ≥30 dpa(steels) testing capability by 2026. Programme optimisation by the pre-testing with fission neutronson isotopically- or chemically-doped steels and with ion-beams is discussed along with the minimum14 MeV testing programme, and the key role which fundamental and mission-oriented modelling canplay in orienting the research

The European ITER Test Blanket Modules: Fabrication R&D progress for HCLL and HCPB

Two concepts have been chosen to be tested in ITER under the form of Test Blanket Modules (TBMs): the Helium-Cooled Lithium-Lead (HCLL) and the Helium-Cooled Pebble-Bed (HCPB). Both European TBMs designs share similar steel box structure which is constituted by a box, made of two Side Caps (SCs) and a First Wall (FW), stiffened by horizontal and vertical Stiffening Plates (SP) and closed on its back by several back plates (BPs). All structure subcomponents are internally cooled by Helium circulating in meandering squared section channels. This paper describes manufacturing technologies developed and implemented to assembly the SPs into the box.It presents the preliminary manufacturing procedure developed and applied for the assembly of the SPs into the box by Tungsten Inert Gas (TIG). Several mock-ups have been manufactured from laboratory to feasibility mock-ups (scale 1:1) on which non-destructive and destructive tests have been carried-out to identify the preliminary manufacturing procedure. Due to TBM specificities (namely complex welding trajectories, heavy and big components, plates with channels, space constraints, …) a specific welding facility including a custom welding torch and an automated bench has been achieved and is also described in the paper.We detail the adopted manufacturing strategies, as the optimization of welding sequence to minimize distortions and the customization of welding parameters, to compensate machining tolerances and welding gaps. Results such as welded joints quality and microstructure, internal cooling channel deformation and structure distortions are reported. These developments have been performed following a standardized procedure complying with professional codes and standards (RCC-MRx)

Optimization of the first wall for the DEMO water cooled lithium lead blanket

The maximum heat load capacity of a DEMO First Wall (FW) of reasonable cost may impact the decision of the implementation of limiters in DEMO. An estimate of the engineering limit of the FW heat load capacity is an essential input for this decision. This paper describes the work performed to optimize the FW of the Water Cooled Lithium-Lead (WCLL) blanket concept for DEMO fusion reactor in order to increase its maximum heat load capacity.The optimization is based on the use of water at typical Pressurised Water Reactors conditions as coolant. The present WCLL FW with a waved plasma-faced surface and with circular channels was studied and the heat load limit has been predicted with FEM analysis equal to 1.0 MW m−2 with respect to the Eurofer temperature limit.An optimization study was then carried out for a flat FW design considering thermal and mechanical constraints assuming inlet and outlet temperatures equal to 285 °C/325 °C respectively and based on geometric design parameters such as channel pitch, diameter of pipes and thicknesses. It became clear through the optimization that the advantages of a waved FW are diminished. Given the manufacturing issues of that concept, the waved FW was therefore not pursued further. Even if the optimization study shows that the maximum heat load could in principle be as high as 2.53 MW m−2, it is reduced to 1.57 MW m−2 when additional constraints are introduced in order not to affect corrosion, manufacturability and Tritium Breeding Ratio in normal condition such as a coolant velocity ≤8 m/s, pipe diameter ≥5 mm and a total FW thickness ≤22 mm.However it is important to note that the FW channels currently fulfill additional functions and are therefore not optimized “at all cost” regarding heat load capacity and the paper points out some recommendations against missing assumptions

Test blanket modules (ITER) and breeding blanket (DEMO): History of major fabrication technologies development of HCLL and HCPB and status

International audienceTwo breeding blanket concepts, the Helium-Cooled Lithium-Lead (HCLL) and the Helium-Cooled Pebble-Bed (HCPB), developed in Europe in the frame of DEMO and relevant TBM studies, present many similarities in terms of design and manufacturing. As an example, all structure sub-components are internally cooled by helium circulating in meandering squared section channels. Several technologies have been investigated in the frame of EU fusion research programme for the manufacturing, including a specialized machining, fusion and diffusion welding and joints inspection, of DEMO breeding blanket and TBM sub-components (Cooling Plates (CP), Side Caps (SCs), Stiffening Plates (SPs), First Wall (FW)) and their assembly, main of which are discussed in this paper. The manufacturability of DEMO blanket modules Back Supporting Structure (BSS), a big structure located behind blanket modules and supporting them, is also discussed. The applicability of technologies takes into account specificities of EUROFER97 steel, foreseen as structural material.For each assessed technology, main results, e.g. in terms of mechanical properties and microstructure of weld joints, are presented and main advantages and drawbacks are summed up, in order to identify most promising technology/ies and to propose manufacturing scenarios. It should be noted that these developments are performed according to standards and professional codes (RCC-MRx). Further development strategies are also briefly discussed in the paper

Status of the EU DEMO breeding blanket manufacturing R&D activities

The realization of a DEMOnstration Fusion Power Reactor (DEMO) to follow ITER, with the capability of generating several hundred MW of net electricity and operating with a closed fuel-cycle by 2050, is viewed by Europe as the remaining crucial step towards the exploitation of fusion power. The EUROfusion Consortium, in the frame of the European Horizon 2020 Program, has been assessing four different breeding blanket concepts in view of selecting the reference one for DEMO. This paper describes technologies and manufacturing scenarios developed and envisaged for the four blanket concepts, including nuclear “conventional” assembly processes as GTAW, electron beam and laser welding, Hot Isostatic Pressing (HIP), and also more advanced (from the nuclear standpoint) technologies as additive manufacturing techniques. These developments are performed in conformity with international standards and/or design/manufacturing codes. Topics as the metallurgical weldability of EUROFER steel and the associated risks or the development of appropriate filler wire are discussed. The development of protective W-coating layers on First Wall, with Functionally Graded (FG) interlayer as compliance layer between W and EUROFER substrate, realized by Vacuum Plasma Spraying method, is also propounded. First layer systems showed promising layer adhesion, thermal fatigue and thermal shock properties. He-cooled mock-ups, representative of the First Wall with FG W/EUROFER coating are developed for test campaigns in the HELOKA facility under relevant heat fluxes.First elements of Double Walled Tubes (DWT) manufacturing and tube/plate assembly for the water cooled concept are given, comprising test campaign aiming at assessing their behaviour under corrosion.In addition, further development strategies are suggested

Status of the EU DEMO breeding blanket manufacturing R&D activities

The realization of a DEMOnstration Fusion Power Reactor (DEMO) to follow ITER, with the capability of generating several hundred MW of net electricity and operating with a closed fuel-cycle by 2050, is viewed by Europe as the remaining crucial step towards the exploitation of fusion power. The EUROfusion Consortium, in the frame of the European Horizon 2020 Program, has been assessing four different breeding blanket concepts in view of selecting the reference one for DEMO. This paper describes technologies and manufacturing scenarios developed and envisaged for the four blanket concepts, including nuclear “conventional” assembly processes as GTAW, electron beam and laser welding, Hot Isostatic Pressing (HIP), and also more advanced (from the nuclear standpoint) technologies as additive manufacturing techniques. These developments are performed in conformity with international standards and/or design/manufacturing codes. Topics as the metallurgical weldability of EUROFER steel and the associated risks or the development of appropriate filler wire are discussed. The development of protective W-coating layers on First Wall, with Functionally Graded (FG) interlayer as compliance layer between W and EUROFER substrate, realized by Vacuum Plasma Spraying method, is also propounded. First layer systems showed promising layer adhesion, thermal fatigue and thermal shock properties. He-cooled mock-ups, representative of the First Wall with FG W/EUROFER coating are developed for test campaigns in the HELOKA facility under relevant heat fluxes. First elements of Double Walled Tubes (DWT) manufacturing and tube/plate assembly for the water cooled concept are given, comprising test campaign aiming at assessing their behaviour under corrosion. In addition, further development strategies are suggested

Human cardiac progenitor cells with regenerative potential can be isolated and characterized from 3D-electro-anatomic guided endomyocardial biopsies

Aims: In the present study, we aimed to develop a percutaneous approach and a reproducible methodology for the isolation and expansion of Cardiac Progenitor Cells (CPCs) from EndoMyocardial Biopsies (EMB) in vivo. Moreover, in an animal model of non-ischemic heart failure (HF), we would like to test whether CPCs obtained by this methodology may engraft the myocardium and differentiate. Methods and results: EMB were obtained using a preformed sheath and a disposable bioptome, advanced via right femoral vein in 12 healthy mini pigs, to the right ventricle. EMB were enzymatically dissociated, cells were expanded and sorted for c-kit. We used 3D-Electro-Anatomic Mapping (3D-EAM) to obtain CPCs from 32 patients affected by non-ischemic cardiomyopathy. The in vivo regenerative potential of CPCs was tested in a rodent model of drug-induced non-ischemic cardiomyopathy. c-kit positive CPCs replicative capacity was assessed in 30 patients. Telomere length averaged 7.4\ub10.4kbp and telomerase activity was present in all preparations (1.7 7105 copies). The in situ hybridization experiments showed that injected human CPCs may acquire a neonatal myocyte phenotype given the expression of the alpha-sarcomeric actin together with the presence of the Alu probe, suggesting a beneficial impact on LV performance. Conclusions: The success in obtaining CPCs characterized by high regenerative potential, in vitro and in vivo, from EMB indicates that harvesting without thoracotomy in patients affected by either ischemic or non-ischemic cardiomyopathy is feasible. These initial results may potentially expand the future application of CPCs to all patients affected by HF not undergoing surgical procedures