IFMIF, the European–Japanese efforts under the Broader Approach agreement towards a Li(d,xn) neutron source: Current status and future options

The necessity of a neutron source for fusion materials research was identified already in the 70s. Though neutrons induced degradation present similarities on a mechanistic approach, thresholds energies for crucial transmutations are typically above fission neutrons spectrum. The generation of He via 56Fe (n,α) 53Cr in future fusion reactors with around 12 appm/dpa will lead to swelling and structural materials embrittlement. Existing neutron sources, namely fission reactors or spallation sources lead to different degradation, attempts for extrapolation are unsuccessful given the absence of experimental observations in the operational ranges of a fusion reactor. Neutrons with a broad peak at 14 MeV can be generated with Li(d,xn) reactions; the technological efforts that started with FMIT in the early 80s have finally matured with the success of IFMIF/EVEDA under the Broader Approach Agreement. The status today of five technological challenges, perceived in the past as most critical, are addressed. These are: 1. the feasibility of IFMIF accelerators, 2. the long term stability of lithium flow at IFMIF nominal conditions, 3. the potential instabilities in the lithium screen induced by the 2 × 5 MW impacting deuteron beam, 4. the uniformity of temperature in the specimens during irradiation, and 5. the validity of data provided with small specimens. Other ideas for fusion material testing have been considered, but they possibly are either not technologically feasible if fixed targets are considered or would require the results of a Li(d,xn) facility to be reliably designed. In addition, today we know beyond reasonable doubt that the cost of IFMIF, consistently estimated throughout decades, is marginal compared with the cost of a fusion reactor. The less ambitious DEMO reactor performance being considered correlates with a lower need of fusion neutrons flux; thus IFMIF with its two accelerators is possibly not needed since with only one accelerator as the European DONES or the Japanese A-FNS propose, the present needs > 10 dpa/fpy would be fulfilled. World fusion roadmaps stipulate a fusion relevant neutron source by the middle of next decade, the success of IFMIF/EVEDA phase is materializing this four decades old dream

Preliminary design of the HEBT of IFMIF DONES

IFMIF-DONES (International Fusion Materials Irradiation Facility–DEMO Oriented Neutron Source) is currentlybeing developed in the frame of the EUROfusion Early Neutron Source work package (WPENS) and will be aninstallation for fusion material testing, that will generate aflux of neutrons of 1018m−2s−1with a broad peak at14 MeV by Li(d,xn) nuclear reactions thanks to a 40 MeV deuteron beam colliding on a liquid Liflow.The accelerator system is in charge of providing such high energy deuterons in order to produce the expectedneutronflux. The High Energy Beam Transport line (HEBT) is the last subsystem of the accelerator and its mainfunctions are to guide the deuteron beam towards the Lithium target and to shape it by the use of magneticelements to the reference beam footprint at the Lithium Target.The present work summarizes the current status of the HEBT design, including beam dynamics, vacuum,radioprotection, diagnostics and remote handling studies performed, along with the layout and integration of theline.This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No 633053. The work done by IREC has been supported by the CERCA Programme from Generalitat de Catalunya (Government of Catalonia).Peer reviewe

Nuclear Analyses for the ITER ECRH Launcher

Computational results of the nuclear analyses for the ECRH launcher integrated into the ITER upper port are presented. The purpose of the analyses was to provide the proof for the launcher design that the nuclear requirements specified in the ITER project can be met. The aim was achieved on the basis of 3D neutronics radiation transport calculations using the Monte Carlo code MCNP. In the course of the analyses an adequate shielding configuration against neutron and gamma radiation was developed keeping the necessary empty space for mm-waves propagation in accordance with the ECRH physics guidelines. Different variants of the shielding configuration for the extended performance front steering launcher (EPL) were compared in terms of nuclear response functions in the critical positions. Neutron damage (dpa), nuclear heating, helium production rate, neutron and gamma fluxes have been calculated under the conditions of ITER operation. It has been shown that the radiation shielding criteria are satisfied and the supposed shutdown dose rates are below the ITER nuclear design limits.JRC.F.4-Safety of future nuclear reactor

Progress in Neutronics for the ITER ECRH Launcher

The paper reports the latest achievements in the neutronics modelling of the electron cyclotron resonance heating (ECRH) launcher installed in the ITER upper port. The computational neutronics analyses have been performed for the extended performance (EP) front steering launcher design, which is accepted by the ITER project as reference. The aim of the paper is to show that the considered launcher design satisfies to the nuclear criteria specified for ITER machine. Results of calculations for the essential nuclear responses such as the neutron fluxes, neutron damages, helium production, and nuclear heating are discussed. The methodology used is focused on Monte Carlo variance reduction techniques for deep-penetration neutron radiation calculations in a very heterogeneous geometry. The Monte Carlo N-particle (MCNP) code was used for the radiation transport calculations with a 3D geometry model of the launcher in ITER machine. The complexity of the launcher geometry makes inevitable to use an automated interface programme McCad for the direct conversion from CAD to MCNP. The results obtained are in compliance with the ITER nuclear regulations. The analyses reveal the necessity of detailed consideration of the most critical launcher components.JRC.F.4-Nuclear Reactor Integrity Assessment and Knowledge Managemen

Radiation Shielding Analyses for the ITER Upper Port ECRH Launcher

The International Thermonuclear Experimental Reactor (ITER) will use an electron cyclotron resonance heating (ECRH) system in the upper port of the device for plasma stabilization, heating, and current drive by injecting millimeter wave beams into the plasma chamber. The millimeter waves are transmitted to the plasma through long and narrow waveguide channels. The required plasma wall openings could result in enhanced neutron radiation loadings to the ECRH launcher and neighboring reactor components. The analyses aimed at proving that the shielding requirements and all related nuclear design limits specified by ITER can be met for the proposed ECRH launcher design concepts. The nuclear criteria included human safety issues, nuclear waste regulation aspects, and radiation shielding requirements. The proof was conducted by calculating the radiation loads to sensitive components such as the diamond window of the ECRH launcher, the vacuum vessel, and the superconducting magnets and assessing the potential radiation doses to work personnel during shutdown periods. Dedicated computational approaches were developed to handle the related neutron streaming and shielding problems on the basis of threedimensional Monte Carlo calculations by the MCNP code. Suitable MCNP models of the launcher were generated by the automatic conversion of the underlying computer assisted design models using a newly developed interface program. The results of the analyses show that all radiation design limits can be safely met for the considered launcher and shield designs.JRC.F.4-Nuclear Reactor Integrity Assessment and Knowledge Managemen

Neutronic Modeling Challenges for the ITER ECRH Launcher Shielding Design

Comprehensive neutronic analyses are being performed for different variants of the International Thermonuclear Experimental Reactor (ITER) electron cyclotron resonance heating upper launcher under development in the European Union making use of modern computation tools such as the McCad code for geometry conversion and the rigorous two-step (R2S) interface for rigorous shutdown dose rate calculation. There were many reasons for the challenges encountered during the shielding analyses: deep-penetrated radiation transport in the complex geometry of the launcher, frequent need to introduce changes in the three-dimensional MCNP model, and necessity to meet a broad range of nuclear sufficiency requirements specified for ITER. The challenges were successfully addressed and resulted in radiation shielding and nuclear safety support for the current version of the launcher design, which should be workable in ITER. During the process of the launcher design development, a comprehensive knowledge of neutronic characteristics has been gained, and computation methods were matured accordingly.JRC.DG.F.4-Safety of future nuclear reactor

Altersbestimmung an thermalen Tiefenwässern im Oberjura des Molassebeckens mittels Krypton-Isotopen

81Kr (half-life 229,000 years) is an ideal tracer for old groundwater. The Upper Jurassic rock in the deep Molasse Basin is an outstanding geothermal groundwater reservoir (with temperatures up to 140 °C). However, due to the complex groundwater evolution (ion and isotope exchange, gas flux, etc.), comprehensive hydrogeological studies completed to date, including 14C‑DIC and He isotopes, could not resolve the recharge dynamics and residence times. Nine geothermal wells were therefore sampled for 81Kr/85Kr employing the laser-based atom trap tracer analysis technique (ATTA). In the western and central basin, the results reveal predominant groundwater recharge during the last glacial period with one sample influenced by infiltration during the earlier glacial period. Recharge signatures and 81Kr-model-ages fit very well to subglacial recharge with cross-formational flow through the sedimentary cover (600 to >3000 m deep). In the eastern basin, the results point to the Cromerian complex, indicating a slower flow system with less influence from recharge during glacial periods.81Kr (T1/2 229.000 a) ist ein idealer Datierungstracer für alte Tiefengrundwässer. Die Oberjura-Formation im tiefen Teil des Molassebeckens stellt ein herausragendes Georeservoir für thermale Tiefenwässer (bis 140 °C) dar. Über die genutzten Thermalwässer mit zumeist kaltzeitlicher Bildungscharakteristik (Na-HCO3-Cl-Typ) ist jedoch im Hinblick auf die Neubildungsprozesse, Herkunftsgebiete und Fließdynamik wenig bekannt. Für die Interpretation der Genese und Entwicklung (Ionen- und Isotopenaustausch, Gasflüsse, etc.) fehlen bislang verlässliche Altersinformationen. Erstmals wurden nun neun thermale Tiefenwässer erfolgreich durch 81Kr/85Kr-ATTA-Untersuchungen datiert. Die abgeleiteten Altersinformationen zeigen im westlichen und zentralen Molassebecken vorherrschend eine Bildung während der letzten Kaltzeit (Würm-Glazial), die sehr gut zur subglazialen Bildungshypothese über alpennahe, sehr mächtige Deckschichten hinweg passt. Im Ostteil des Molassebeckens weisen die Tiefenwässer hingegen einheitlich deutlich höhere Alterscharakteristiken (Günz/Mindel Interglazial) bzw. ein langsameres Strömungssystem auf, das allenfalls durch geringe Neubildungsanteile aus den jüngeren alpinen Vergletscherungen beeinflusst ist

Analysis of the ITER ECH Upper Port Launcher remote maintenance using virtual reality

All ITER sub-systems of remote handling (RH) classes 1 and 2 have to be remotely maintainable. The maintenance strategy for these components has to ensure system availability after failure or scheduled maintenance. This paper shows how virtual reality (VR) simulation [1] can be used as a tool to analyze the maintenance process, to predict the mean time to repair and to ensure the RH compatibility of one ITER sub-system, the Upper Port Launcher (UPL) [2]. Special emphasis is put on the development of RH procedures and the identification of tooling requirements. The possibility to Simulate RH logistics and repair actions in an early stage of the design process allows for the identification of those maintenance actions that require dedicated tests in the Launcher Handling Test Facility at Karlsruhe. The VR analysis. together with dedicated mock-up tests will demonstrate the RH compatibility of the UPL plug, provide input to the design of the Port Plug maintenance area in the ITER Hot Cell, and support the development of RH maintenance tooling. (C) 2009 Published by Elsevier B.V

Progress of fusion nuclear technologies in the broader approach framework

In the Broader Approach framework, the International Fusion Materials Irradiation Facility/Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) project, the International Fusion Energy Research Center (IFERC) project, and the Satellite Tokamak project are implemented. In the IFMIF/EVEDA project, engineering design of IFMIF and engineering R&D include the construction and tests of an IFMIF prototype accelerator system up with a 9 MeV and ON deuteron beam, a liquid lithium test loop with free surface flow, and full scale irradiation test module including temperature control instrumentation. The commissioning of the EVEDA lithium test loop was completed in March 2011, and a lithium flow of similar to 5 m/s was obtained. As a part of the IFERC project, R&Ds on reduced activation ferritic/martensitic steels as blanket structural material, SiCf/SiC composites as a flow channel insert material and/or alternative structural material, advanced tritium breeders and neutron multipliers, and tritium technology are carried out. At the beginning of 2011, the integrated DEMO design team was established among the IFERC project team and EU/JA home teams, where the design criteria, other design basis are discussed as an initial work. A high performance supercomputer with the peak performance of 1.3 Pflops is under installation at the Rokkasho BA site. (C) 2012 Elsevier B.V. All rights reserved