International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source Research Articles

Assessment of different lifting devices for the shipping bays for DONES main building

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

Study of the production of radioisotopes at IFMIF-DONES: 177Lu with deuterons

The production of radioisotopes for nuclear medicine is boosted by different international agencies. The International Fusion Materials Irradiation Facility - Demo Oriented NEutron Source (IFMIF-DONES) will be a infrastructure for testing under high neutron flux the materials to be used in future DEMO fusion reactor. IFMIF-DONES will generate neutrons by means of the impact of a high-power deuteron beam onto a lithium-jet target. There is an important effort to take advantage of the outstanding characteristics of the facility in terms of neutrons and deuterons. Thus, a complementary program is being developed, where the production of radioisotopes for medicine is one of the main applications. Here, we discuss the production of 177Lu with deuterons at IFMIF-DONES.

Interactive simulations as a tool for logistics and maintenance of IFMIF-DONES

Pre-configured virtual reality (VR) simulations of the logistics and maintenance processes have proven to be useful for identifying potential design issues as well as planning operations during an early design phase of facility. But VR simulations can also be used to deeply explore the feasibility of these procedures in a more interactive manner, so that we can identify potential risks and difficulty levels from early stages and study different maintenance strategies to assist the maintenance worker during these procedures. This article presents a framework to design and validate logistics and maintenance procedures in complex facilities, such as the International Fusion Materials Irradiation Facility DEMO Oriented Neutron Source (IFMIF-DONES). Our framework begins with a preparatory phase where essential information about the procedures and Computer-Aided Design (CAD) models is compiled into a comprehensive Virtualization Task Document (VTD). Differently from previous work, this VTD allows representation of parallel tasks. We implement the interactive version of the virtual environment, where the different maintenance and logistics equipment, as well as a virtual maintenance worker is controlled by the user (the person executing the interactive simulation). We have validated this interactive framework with two simulations for the installation process of the Superconducting Radio Frequency Linear accelerator (SRF Linac) modules in IFMIF-DONES. In one simulation (the automatic one), the procedures are reproduced as they are planned, while in the second simulation (the interactive one) the user freely controls the movements of the moving parts of the crane, grab and release plant equipment, move platforms, etc. Based on our simulations, the interactive version allows easier detection of potential points of collisions as well as more precise assessment of the difficulty of the tasks to be performed.

Engineering design status of IFMIF-DONES High Energy Beam Transport line and Beam Dump system inside the TIR and RIZ

IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is a fusion materials testing facility that is currently being designed under the framework of a work package of the EUROfusion Consortium. It will use a 125mA at 40MeV deuteron beam to generate a high neutron flux through Li(d,xn) stripping nuclear reactions in a liquid lithium target. The High Energy Beam Transport line (HEBT), the most upstream system of the IFMIF-DONES accelerator, is responsible for the guidance and shaping of the beam towards the target. Additionally, during commissioning periods, the HEBT is also responsible for diverting the beam, through the Beam Dump Transport Line, to the Beam Dump for testing purposes. The HEBT is spread along different rooms and zones: the Accelerator Vault, the Radiation Interface Zone (RIZ), and Target Interface Room (TIR). The engineering design of the HEBT components situated within the TIR and RIZ has been updated to satisfy new requirements, with a focus on ensuring the protecting of the Fast Isolation Valve (FIV) from the backscattered radiation from the target. These modifications include relocating the FIV from the TIR to the RIZ, adjusting the building layout to accommodate the new FIV module, configuring an enclosure cabinet for the RIZ, and adding local shielding to extend the lifetime of the FIV seal actuators. This work describes the current status of these TIR and RIZ engineering design, including radioprotection, commissioning and maintenance plan, beam diagnostics devices, beam dynamics and new remote handling approaches, as well as the layout and integration of the required components along the beamline. The TIR and RIZ are critical areas for IFMIF-DONES, and their design and operation must be compliant with functional, reliability and safety requirements. The updated design addresses potential issues and enhances the facility’s overall functionality.

DONES EVO: Risk mitigation for the IFMIF-DONES facility

The International Fusion Materials Irradiation Facility- DEMO Oriented Neutron Source (IFMIF-DONES) is a scientific infrastructure aimed to provide an intense neutron source for the qualification of materials to be used in future fusion power reactors. Its implementation is critical for the construction of the fusion DEMOnstration Power Plant (DEMO).IFMIF-DONES is a unique facility requiring a broad set of technologies. Although most of the necessary technologies have already been validated, there are still some aspects that introduce risks in the evolution of the project.In order to mitigate these risks, a consortium of companies, with the support of research centres and the funding of the CDTI (Centre for the Development of Industrial Technology and Innovation), has launched the DONES EVO Programme, which comprises six lines of research:•Improvement of signal transmission and integrity (planning and integration risks)•Optimisation of RF conditioning processes (planning and reliability risks)•Development of a reliable beam extraction device (reliability risks)•Development of technologies for the production of medical isotopes (reliability risks)•Improvement of critical parts of the lithium purification system (safety and reliability risks)•Validation of the manufacture of critical components with special materials (reliability risk).DONES EVO will focus on developing the appropriate response to the risks identified in the IFMIF-DONES project through research and prototyping around the associated technologies.This contribution will present a discussion of the risks, the proposed response to them and the evolution of the technologies involved, following selected experiments carried out throughout the project.

The LiFIRE experimental facility: Final design, construction and experimental campaign

Recently, nuclear fusion-related experiments and dedicated facilities worldwide relying on the usage of liquid metals are experiencing a renewed interest.This is the case of the International Fusion Materials Irradiation Facility – DEMO-Oriented Neutron Source (IFMIF-DONES), a radioactive facility which will use several cubic meters of pure liquid lithium as a target for deuterons to produce high neutron fluxes having an energy spectrum as effective as the expected fusion reactors. The primary mission of IFMIF-DONES will be to irradiate selected candidate structural materials for building a comprehensive database on fusion material properties.Generally, alkali metals, such as lithium, exhibit safety issues related to their chemical reactive nature and material compatibility. Due to the wide uncertainty regarding the lithium behavior confirmed by an extensive literature review, a dedicated experimental facility has been conceived to primarily study lithium ignition conditions in support of the licensing process of IFMIF-DONES. The ultimate purpose of the LiFIRE facility will be to demonstrate by means of experimental evidences the set of requirements on lithium fire protection to be applied to the final engineering design of IFMIF-DONES.This work describes the final design, construction and experimental campaign of the LiFIRE facility currently under development at CIEMAT's premises.

Updates of the removable biological shielding blocks inside of the test cell, part of the test systems of IFMIF-DONES

The International Fusion Materials Irradiation Facility - DEMO Oriented Neutron Source (IFMIF-DONES) is a facility which is designed under the framework of the EU fusion roadmap. It is going to be an essential irradiation facility for testing and qualifying candidate materials under severe irradiation conditions of a neutron field having an neutron irradiation effect on materials like the one expected in a commercial fusion power reactor. The material specimens are irradiated in a containment structure named Test Cell (TC), which is part of the Test Systems (TS).The first protecting „barrier” against irradiation affecting the surrounding of the TC, are the Removable Biological Shielding Blocks (RBSBs). These ∼9 m height, ∼80 tons elements, which are formed by stainless steel liners filled with heavy concrete, need to be remotely handled as after the first experiments they will get dose rates above the hands-on limit. Irradiation will also result in a large nuclear heat power deposited in the shielding blocks, therefore needs to be actively water cooled by a system of embedded pipes to control the temperature.In this paper the updated design of the RBSBs is described, including the latest achievements and proposals for feasible manufacturing, lifting and positioning possibilities of the blocks inside of the TC respecting the given tolerances.

Opportunities for high-energy neutron- and deuteron-induced measurements for fusion technology at the Soreq applied research accelerator facility (SARAF)

The Soreq Applied Research Accelerator Facility (SARAF) will be based on a 40 MeV, 5 mA CW (continuous wave) proton/deuteron superconducting linear accelerator, currently under construction at Soreq Nuclear Research Center in Yavne, Israel. It is planned to commence operation during 2025. Experiments at SARAF could provide data on high-energy deuteron- and neutron-induced cross-sections, yields and radiation damage, which are invaluable for the design and operation of the International Fusion Materials Irradiation Facility-DEMO-Oriented NEutron Source (IFMIF-DONES), and fusion technology in general. Pulsed beams (∼1 nsec) of variable energy deuterons will irradiate a lithium target and generate pulsed neutron beams with energy up to ∼55 MeV, which will be used to measure energy-dependent neutron-induced differential cross-sections, utilizing time of flight techniques. Impinging continuous wave (CW) 40 MeV deuteron beams on a unique gallium-indium (GaIn) liquid-jet target, will generate a neutron rate of more than 1 × 1015 n/sec, with energies up to ∼45 MeV. We plan to use this high rate to measure integral neutron-induced reaction yields of all channels simultaneously, employing an original novel method that will identify the reaction-produced nuclei via accurate mass measurement. The neutron-energy dependence of the yields could be deduced by combining measurements at various deuteron energies. The measured cross-sections and yields at SARAF may predict the activation characteristics of construction materials of IFMIF-DONES and future fusion reactors. The deuteron beams will also be used directly to measure cross-sections via in-beam and offline methods. The high neutron and deuteron rates will extend SARAF’s reach to rare materials. The deuteron beam power density on the liquid GaIn target will be 100 kW/cm2(similar to IFMIF-DONES) on a 2 cm2spot. The resulting neutron flux on small secondary samples will be in the 1013 n/cm2/s level, only an order of magnitude less than IFMIF-DONES. Therefore, SARAF may serve as a pilot facility for fusion-related radiation damage studies, providing important information towards the design of IFMIF-DONES.

Conjugated heat transfer analysis of the Start-Up Monitoring Module (STUMM) for IFMIF-DONES including heat generation mapping

The Start-Up Monitoring Module (STUMM) is designed for the commissioning phase of the IFMIF-DONES (International Fusion Materials Irradiation Facility – Demo Oriented NEutron Source). The main aim is the detailed characterization of the irradiation field in space for the validation of the nuclear models. The thermo-hydraulic analysis of the STUMM was carried-out in the Ansys FLUENT software predicting the steady-state temperature distribution in the full range of the allowable inlet temperatures (15–60 °C), inlet pressures (3–3.5 bar), and the maximum allowable helium flow rate of 0.18 kg/s. The heat generation maps obtained from MCNP analyses were mapped on the CFD mesh via the in-build FLUENT functionality of “profiles”. To ensure the conservation of the global heat generation a correction coefficient αcorr was introduced to modify the MCNP profiles before the import to CFD: qCFD(x,y,z)=αcorr qMCNP(x,y,z). A dedicated test case of a cylinder subjected to a point irradiation source was studied, confirming the convergence of the global heat with a refinement of the MCNP and CFD discretization, where the MCNP model was discretized with cuboid cells and the CFD with a polyhedral. The global STUMM model was solved with 5 MCNP profiles with cell sizes from 5 mm to 1 mm (0.2–23.3 mln data points). Even though the smallest feature of the global CFD model was 0.5 mm (thickness of a detector wall) the MCNP profile with ∼4 mm cuboid cells gave almost identical results to the finest 1 mm profile, confirming the precision of the method and no need of solving very finely discretized MCNP models. With the direct transfer of results between MCNP and CFD model with the in-build FLUENT functionality of “profiles”, the simulation set-up was fast. A negligible impact of the internal radiation heat transfer on the temperatures was found (with the Discrete Ordinates (DO) model). Two possible flow directions of the helium were analysed for the worst-case scenarios. With the maximum pressure drop of 4.12 kPa, the maximum helium outlet temperature of 71.6 °C, and the max temperature of the detectors of 157.5 °C all the design requirements were satisfied, as values were far from the limits of 60–80 kPa, 150 °C and 250 °C respectively.

Integrated Design of the Vacuum and Safety Barrier between the Lithium and Test Systems of IFMIF-DONES

The international fusion materials irradiation facility-DEMO-oriented neutron source (IFMIF-DONES) is a facility that is designed under the framework of the EU fusion roadmap. It is going to be an essential irradiation facility for testing and qualifying candidate materials under severe irradiation conditions of a neutron field having an energy spectrum like the one present in a fusion power reactor. The material specimens are irradiated in a containment structure named the test cell (TC), which is part of the test systems (TS). The TC also houses a part of the other major system (lithium system, LS), which provides the liquid lithium for the reaction through a piping system. At a point, the lithium piping needs to exit the TS, but the primary safety boundary must be continuous around these penetrations. Therefore, a special barrier, called the test systems–lithium systems interface cell (TLIC), has been developed around the piping system to provide a safety-approved and remotely maintainable vacuum boundary envelope. In this paper, the integrated design development of the TLIC is described, consisting of the design development according to the RCC-MRx code, the remote-handling (RH) needs, and the procedures and safety-related special needs of the design.

Shielding analyses supporting the Lithium loop design and safety assessments in IFMIF-DONES

The assessment of radiation fields in the lithium loop pipes and dump tank during the operation were performed for International Fusion Materials Irradiation Facility – DEMO-Oriented NEutron Source (IFMIF-DONES) in order to obtain the radiation dose-rate maps in the component surroundings. Variance reduction techniques such as weight window mesh (produced with the ADVANTG code) were applied to bring the statistical uncertainty down to a reasonable level. The biological dose was given in the study, and potential shielding optimization is suggested and more thoroughly evaluated. The MCNP Monte Carlo was used to simulate a gamma particle transport for radiation shielding purposes for the current Li Systems’ design. In addition, the shielding efficiency was identified for the Impurity Control System components and the dump tank. The analysis reported in this paper takes into account the radiation decay source from and activated corrosion products (ACPs), which is created by d-Li interaction. As a consequence, the radiation (resulting from ACPs and Be-7) shielding calculations have been carried out for safety considerations.

The IFMIF-DONES Project: Design Status and Main Achievements Within the EUROfusion FP8 Work Programme

International Fusion Materials Irradiation Facility-DEMO-Oriented NEutron Source (IFMIF-DONES) is a high-intensity neutron irradiation facility for qualification of fusion reactor materials, which is being designed as part of the European roadmap to fusion-generated electricity. Its main purpose is to study the behavior of materials properties under irradiation in a neutron flux able to simulate the same effects in terms of relevant nuclear responses as those expected in the first wall of the DEMO reactor which is envisaged to follow ITER. It is thus a key facility to support the design, licensing and safe operation of DEMO as well as of the fusion power plants that will be developed afterwards. The start of its construction is foreseen in the next few years. In this contribution, an overview of the IFMIF-DONES neutron source is presented together with a snapshot of the current engineering design status and of the relevant key results achieved within the EUROfusion Work Package Early Neutron Source (WPENS) as part of the 2014–2020 EURATOM Research and Training Programme, complementary to the EU Horizon 2020 Framework Programme (FP8). Moreover, some information on the future developments of the project are given.

Nuclear data libraries for IFMIF-DONES neutronic calculations

International Fusion Materials Irradiation Facility-DEMO Oriented NEutron Source (IFMIF-DONES) is an installation aimed to irradiate with a high neutron flux materials relevant for the construction of the DEMOnstration fusion power plant (DEMO), in order to study the damage due to irradiation. Neutrons are generated using a 40 MeV and 125 mA deuteron beam impinging on a thick liquid lithium target. With these characteristics, damage due to irradiation comparable to that in the first wall of a fusion power reactor is achieved. In this paper we investigate the differences in the neutronic calculations of the IFMIF-DONES design when using different nuclear data libraries. We first studied the differences in neutron production due to Li(d, xn) reactions between different models and evaluations, comparing the different results with experimental data. Additionally, we tested the performance of the MCNP6.2 and Geant4 Monte Carlo codes when using deuteron incident data libraries. Then, we performed neutronic calculations of the IFMIF-DONES design using the most reliable Li(d, xn) neutron production models available, which are the FZK-2005 and JENDL/DEU-2020 evaluations according to the results obtained in the first part of the study. Thus, the differences in these evaluations are propagated to different neutronic calculation results: neutron flux, primary displacement damage, gas production, and heating in the materials to be irradiated. Finally, we also carried out these same neutronic calculations while using different nuclear data libraries for the neutron transport.

Evaluation of the impact of experimental fusion-aimed installations on their area of influence: the price of sustainable energy

The need of clean, stable, safe and free of uncertainty energy sources has been increased after the current geopolitical tension. In this framework, nuclear energy is receiving renewed attention which finally led the European Commission to consider it as Green Energy. In spite of the expected "golden age" of nuclear energy, the fission still has some problems that must be solved. For this reason, the research on nuclear fusion is now and more than ever a real must. The path towards the control of fusion is plenty of technical difficulties, mainly related to the extreme temperatures and pressures needed and also to the neutronic radiation. The International Fusion Materials Irradiation Facility – Demo Oriented NEutron Source (IFMIF-DONES) is an experimental facility whose target s the testing of materials with fusion-like neutrons in order to evaluate the damages and decide which material is the most convenient to build the future reactors. The impact of IFMIF-DONES on the people living in the area where it is going to be located (Escúzar, Province of Granada, Spain) has been evaluated through a survey among its inhabitants. The results are presented and discussed in this work.

Electrochemical hydrogen detection in DONES loop materials

• Design of an electrochemical sensor adequate to RAMI conditions of IFMIF-DONES. • Determination of hydrogen in liquid lithium. • Online electrochemical muliplex monitoring. • Modular design for different extended approaches (impurities, electrochemical procedures, sizes). The radiation-induced degradation of materials in fusion systems is planned to be investigated in IFMIF-DONES ( International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source ), where fast neutrons are produced by a reaction of deuteron-beams with a liquid lithium target. A by-product as critical impurity is hydrogen, which might affect the reliable and safe operation of the IFMIF-DONES loops. Therefore, an important issue is the measurement and control of the hydrogen impurity concentrations in liquid lithium. Initially, a practically applicable direct measurement of hydrogen concentrations in lithium facilities did not exist. However, one promising approach to manage this issue is based on the electrochemistry of the DONES materials The developed Electro-Chemical Hydrogen Sensor for Liquid Lithium (ECHSLL) allows the measurement of the electromotive Force (EMF) between a reference materials system and the loop lithium melt, and thus the monitoring of the hydrogen impurity concentrations. This article will show backgrounds of non-metallic impurities in liquid metal materials and the specific material stabilities within DONES. Liquid lithium is a very reactive material. Therefore critical issuesareviable materials compatibilities, the interactions with hydrogen and the transport behaviour of H-ions in electrolytes at the applied temperatures. Further issues are also the syntheses of the electrochemical materials, as hydrogen conducting electrolytes, reference electrode systems and the different procedures (heat treatments and conditioning steps). The tests showed the functionality of the developed H-sensor. Beyond that, the used material combinations exhibited reliable behaviour in melts under harsh conditions. Hence, the most critical aspect (stability of the sensor materials in the Li-melt) has been resolved by using niobium sensor heads. The observed experimental EMF potentials are in good accordance compared with calculated models, also in long-time experiments.

New approach to the conceptual design of STUMM: A module dedicated to the monitoring of neutron and gamma radiation fields generated in IFMIF-DONES

International Fusion Materials Irradiation Facility — DEMOOriented Neutron Source (IFMIF-DONES) is a planned powerful neutron source, which will generate an intense flux of neutrons (up to ∼1015n/s/cm2) with a fusion-relevant energy spectrum. It will be an accelerator source based on deuteron beam - lithium target reactions. The engineering design of IFMIF-DONES is elaborated in the frame of the Early Neutron Source work package of the EUROfusion consortium. The facility will be dedicated to the irradiation of suitable structural materials planned for the construction of future fusion reactors such as DEMO (Demonstration Fusion Power Plant). Start-up Monitoring Module (STUMM) is designed to monitor radiation and thermal conditions during the commissioning phase of IFMIF-DONES, characterize the produced neutron flux and validate neutronic modeling of the facility. The conceptual design of STUMM is prepared by a team of physicists and engineers from the Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN) and the National Centre for Nuclear Research (NCBJ), Poland. This paper presents the concept of STUMM, the proposed design of the module, and selected measuring systems.

Strategical Approach for the Neutronics in the European Fusion Programme

One of the main aims of the European fusion programme is the design of a DEMOnstration fusion power plant (DEMO). The related work is conducted by the EUROfusion consortium and includes a strong supporting research and development programme. Support is also provided to the design of the high intense neutron source IFMIF-DONES (International Fusion Material Irradiation Facility-DEMO Oriented NEutron Source) to be built for the qualification of materials considered for DEMO. Neutronics plays a fundamental role for the design, operation, and safety of these facilities including the evaluation and verification of their nuclear performance. The lessons learned during the ITER design and construction phase point to the need to strengthen nuclear design integration already in the early DEMO design phase and establish an improved nuclear safety culture. This requires a coordinated approach for the neutronics that relies upon the availability of suitable computational procedures, tools, and data, qualified and validated for specific design- and safety-related applications. Accordingly, the approach builds on the development of advanced computation tools and the provision of high-quality nuclear data supported by integral experiments for their validation. Furthermore, configuration and requirement management principles ensure the alignment with the global nuclear design integration. This translates into appropriately chosen design margins and acceptance criteria, along with the specification of the nuclear analyses to be conducted in the various design phases. This paper presents the outlined approach as implemented in the EUROfusion Power Plant Physics and Technology (PPPT) programme and provides a strategical outlook of planned activities. This includes development works on advanced simulation tools with their application in various nuclear design- and safety-related analyses. The efforts to improve the nuclear database, in particular, with regard to radiation damage and activation cross-section data relevant to DEMO and DONES, are highlighted. Furthermore, the methodological approach applied to PPPT nuclear analyses including design, shielding, activation, and radiation dose calculations is discussed on the basis of specific examples.

Hydraulic analysis of the start-up monitoring module (STUMM) for IFMIF-DONES

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

First validation experiments of the prototype solid state RF system for IFMIF-DONES

Following the current tendency towards solid-state (SS) amplification technology, the IFMIF-DONES (International Fusion Materials Irradiation Facility - DEMO-oriented Neutron Source) Radiofrequency (RF) Power System will be fully based on SS technology. A challenging issue in high power SS amplifiers is focused on the search of an efficient combination technique for a very large number of power signals. A promising RF power combination technique has been proposed for IFMIF-DONES: a resonant cavity combiner. The crucial characteristic of this combining technology is that the high power combination is achieved in just one step, by means of coupling the outputs of a large number of active devices into a resonant circuit. This improves the efficiency compared with traditional corporate topologies, which is a key aspect for SS amplifiers. In addition, it results in a very compact design, although its circular shape may complicate the design of other SSPA components, which are more standardized for rectangular cubicles or rack solutions. In order to demonstrate the feasibility of this combination technology for the IFMIF-DONES RF Power System, a prototype cavity combiner has been designed and fabricated. It has been validated at small-signal and at medium-high power levels: up to 24 kW in continuous wave (CW) and 100 kW in pulsed mode (duty cycle DC = 4%). The design of this prototype combiner and the results of the first validation experiments are presented in this paper.

Extension and benchmarking of the OpenMC code for accelerator-based neutron source applications

OpenMC is a community developed Monte Carlo (MC) code for neutron and photon transport calculations. In this work, the OpenMC code has been extended and benchmarked for accelerator-based neutron source applications, such as the IFMIF-DONES (International Fusion Material Irradiation Facility- DEMO Oriented NEutron Source) with neutron energies up to 55 MeV. A spherical computational benchmark and the TIARA high energy neutron shielding experiment has been employed for the benchmarking including also comparisons to the results of the well-validated MC code MCNP as reference. The neutron fluxes computed for spherical benchmarks of selected elements show good agreement between OpenMC and MCNP. A problem has been identified and fixed in the secondary photon transport of the OpenMC code. For the TIARA experiment on iron and concrete shielding, the results of OpenMC are in good agreement with MCNP, and the discrepancies between the experiment results and OpenMC simulated results are considered acceptable. In summary, these benchmarks provide good evidence of the suitability of OpenMC for accelerator-based neutron source applications in the energy range up to 55 MeV, with possibility of further extensions depending on the used nuclear data.