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

In the framework of the current IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the backplate) while continuing to operate the rest of the target for a longer period (bayonet backplate concept). With the objective of evaluating the performances of the system in terms of temperature, stress and displacement fields evolution during start-up and shutdown phases, an uncoupled thermomechanical transient analysis has been performed in close collaboration with the University of Palermo by means of a qualified finite element (FE) thermomechanical code. The calculations employed a realistic 3D time-dependent FE model which takes into account all the mechanical and thermal loads including the nuclear heating due to neutron and prompt gamma fields during start-up and decay power of activated products during shutdown. The nuclear data have been calculated by ENEA as part of a parallel extensive neutronic analysis carried out through the MCNP transport code and the EASY-2010 activation code package and then passed as input to the thermomechanical FE model. In this paper, the results of the above transient analyses are reported, highlighting the relevant indications obtained with respect to the fulfillment of the design requirements and possible hints for improving the system design. In particular, it is found that ITER design rules taking into account secondary loads are not always fulfilled during the transient, whereas the predicted displacements allow to exclude any contact of the target system with the surrounding structures. © 2014 Elsevier B.V.

In the framework of the current IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the backplate) while continuing to operate the rest of the target for a longer period (bayonet backplate concept). In this work, the results of the steady state thermomechanical analysis of the IFMIF EU target assembly are briefly reported highlighting the relevant indications obtained with respect to the fulfillment of the design requirements. © 2013 IEEE.

The International Fusion Materials Irradiation Facility (IFMIF) is an accelerator-driven intense neutron source where candidate materials for fusion reactors will be tested and validated. The high energy neutron flux is produced by means of two deuteron beams (total current of 250 mA, energy of 40 MeV) that strikes a liquid lithium target circulating in a lithium loop of IFMIF plant. The European (EU) contribution to the development of the lithium facility comprises five procurement packages, as follow: (1) participation to the experimental activities of the EVEDA lithium test loop in Oarai (Japan); (2) study aimed at evaluating the corrosion and erosion phenomena, promoted by lithium, for structural fusion reference materials like AISI 316L and Eurofer; (3) design and validation of the lithium purification method with the aim to provide input data for the design of the purification system of IFIMF lithium loop; (4) design and validation of the remote handling (RH) procedures for the refurbishment/replacement of the EU concept of IFMIF target assembly including the design of the remote handling tools; (5) the engineering design of the European target assembly for IFMIF and the safety and RAMI analyses for the entire IFMIF lithium facility. The paper gives an overview of the status of the activities and of the main outcomes achieved so far. © 2013 Elsevier B.V. All rights reserved.

A thermo-hydraulic analysis of high-speed free surface Li flow over a concave plate (IFMIF geometry) is performed.Simulations are done for bulk velocities between 10m/s and 20m/s using ANSYS Fluent. A pre-computed heat sourcewas imposed at the center of the curved section to simulate the interaction of a dual deuteron beam with the Li jet.LES and k- models were used for turbulence modeling and Volume of Fluid and Level Set methods were used tomodel the free surface flow. Results reported are the variation of temperature, pressure and velocities across the Lijet at various locations along the curved region. Safety margins before Li starts boiling are also predicted. All casespredicted smooth surfaces without any waves.Keywords:IFMIF, variable curvature backplate, LES, k- , RANS, thermohydraulic1. IntroductionThe purpose of the International Fusion Materials Ir-radiation Facility (IFMIF) is to test and qualify mate-rials that can be operated at high temperatures and un-der intense (neutron) radiation, conditions typical of nu-clear fusion devices. In IFMIF, material samples to beanalyzed will be exposed to an intense neutron flux cre-ated by bombarding a dual deuteron beam on a free sur-face liquid lithium (Li) flow over a concave backplate.A high speed flow is required to rapidly and continu-ously evacuate the heat deposited by the two deuteronbeams. The curvature of the backplate is necessary toprevent Li from boiling due to the high energy deposi-tion by the deuteron beams. To test the conceptual de-sign of IFMIF various mock up experiments and simu-lations on geometries similar to IFMIF were performed.In particular, Gordeev et al. [1, 2], studied the e ect ofunsteady structures generated by nozzle and straighten-ers on the free surface and preferred the use of entirelycurved back-surface for the facility. Gordeev et al. [3]studied the e ects of vortices generated in the flow dueto turbulence and relaxation of the flow bounded by noz-zle walls to a free surface flow on the stability on the Lifree surface and found good match with experiments.IPPE (Institute for Physics and Power Engineering) testcase [4] is a similar setup where the influence of the ge-ometrical design and inflow parameters were tested fortheir e ects on the surface stability of the flow.The hydrodynamic stability of the lithium jet in thetarget section is an important problem in the IFMIF tar-get creation [4]. Through the years, various design im-provements (like the use of a two-stage SHIMA nozzleinstead of a single stage one, confirmation of a stablefree surface jet flow in experiments like IPPE and con-firmation through analysis that heated Li will not boilthanks to the high pressure on the concave backplate)have now shifted the focus of the research on the sta-bility of the Li jet free surface [5]. Most of the pub-lished experiments [4, 6, 7, 8] have shown the presenceof surface waves in the bulk velocity range of 10m/sto 20m/s. Various numerical studies on the surfacestability have also demonstrated the presence of thesewaves [1, 3, 4, 9]. Gordeev et al. outline four types ofinstabilities that can a ect the free surface [1]. Basedon this classification, the reported surface perturbationscan be grouped in three categories - a) due to the insta-bility of the shear layer (Kelvin-Helmholtz instability orsudden relaxation to free surface from a wall boundedflow), b) due to impurities / solidified lithium stuck atthe nozzle exit or due to the side walls (Newton waves)and c) due to the geometry of the structure (changein backplate curvature or divergence of the nozzle andopen channel). Turbulence generated in the nozzle andat the backplate along with the possible generation of

In the framework of the IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the backplate) while continuing to operate the rest of the target for a longer period (the so-called bayonet backplate concept). In this work, the results of the steady state thermomechanical analysis of the IFMIF bayonet target assembly under two different design loading scenarios (a "hot" scenario and a "cold" scenario) are briefly reported highlighting the relevant indications obtained with respect to the fulfillment of the design requirements. In particular, the analyses have shown that in the hot scenario the temperatures reached in the target assembly are within the material acceptable limits while in the cold scenario transition below the ductile to brittle transition temperature (DBTT) cannot be excluded. Moreover, results indicate that the contact between backplate and high flux test module is avoided and that the overall structural integrity of the system is assured in both scenarios. However, stress linearization analysis reveals that ITER Structural Design Criteria for In-vessel Components (SDC-IC) design rules are not always met along the selected paths at backplate middle plane section in the hot scenario, thus suggesting the need of a revision of the backplate design or a change of the operating conditions. © 2015 Elsevier B.V.

The International Fusion Materials Irradiation Facility (IFMIF), presently in its Engineering Validation and Engineering Design Activities (EVEDA) phase under the frame of the Broader Approach Agreement between Europe and Japan, accomplished in summer 2013, on schedule, its EDA phase with the release of the engineering design report of the IFMIF plant, which is here described. Many improvements of the design from former phases are implemented, particularly a reduction of beam losses and operational costs thanks to the superconducting accelerator concept, the re-location of the quench tank outside the test cell (TC) with a reduction of tritium inventory and a simplification on its replacement in case of failure, the separation of the irradiation modules from the shielding block gaining irradiation flexibility and enhancement of the remote handling equipment reliability and cost reduction, and the water cooling of the liner and biological shielding of the TC, enhancing the efficiency and economy of the related sub-systems. In addition, the maintenance strategy has been modified to allow a shorter yearly stop of the irradiation operations and a more careful management of the irradiated samples. The design of the IFMIF plant is intimately linked with the EVA phase carried out since the entry into force of IFMIF/EVEDA in June 2007. These last activities and their on-going accomplishment have been thoroughly described elsewhere (Knaster J et al [19]), which, combined with the present paper, allows a clear understanding of the maturity of the European-Japanese international efforts. This released IFMIF Intermediate Engineering Design Report (IIEDR), which could be complemented if required concurrently with the outcome of the on-going EVA, will allow decision making on its construction and/or serve as the basis for the definition of the next step, aligned with the evolving needs of our fusion community. © 2015 IAEA, Vienna.