Abingdon, United Kingdom
Abingdon, United Kingdom

The European Atomic Energy Community is an international organisation founded in 1957 with the purpose of creating a specialist market for nuclear power in Europe, developing nuclear energy and distributing it to its member states while selling the surplus to non-member states. It is legally distinct from the European Union , but has the same membership, and is governed by the EU's institutions.Currently, its main focus is on the construction of the International Fusion Reactor ITER financed under the nuclear part of FP7. Euratom also provides a mechanism for providing loans to finance nuclear projects in the EU.It was established by the Euratom Treaty on 25 March 1957 alongside the European Economic Community/EEC, being taken over by the executive institutions of the EEC in 1967. Although other communities were merged in 1993 and 2009, the nuclear program has maintained a legally distinct nature from the European Union. Wikipedia.

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This article has been supplied by SCK•CEN. Since 1998 SCK•CEN is developing the MYRRHA project as an accelerator driven system (ADS) based on the lead-bismuth eutectic (LBE) as a coolant of the reactor and a material for its spallation target. MYRRHA is a flexible fast-spectrum pool-type research irradiation facility, also serving since the FP5 EURATOM framework as the backbone of the Partitioning & Transmutation (P&T) strategy of the European Commission concerning the ADS development in the third pillar of this strategy. MYRRHA is proposed to the international community of nuclear energy and nuclear physics as a pan-European large research infrastructure in ESFRI to serve as a multipurpose fast spectrum irradiation facility for various fields of research. The subcritical core of the MYRRHA reactor (~100 MWth) has to be driven by a 600 MeV proton beam with a maximum intensity of 4 mA. The ADS application requires this beam to be delivered in a continuous regime — the resulting beam power of 2.4 MW classifies the driver machine as a High Power Proton Accelerator. Already in the early design phase of MYRRHA the choice for linac has been endorsed, motivated to a large extent by the unprecedented reliability requirements. The design of the MYRRHA linac has been conducted   through an intense European collaborative effort and supported by several consecutive Euratom FP’s. Today the design effort is pursued under the H2020 MYRTE project complemented by several bilateral collaboration agreements. The MYRRHA linac consists of 2 fundamental entities: (i) the injector and (ii) the main linac. The injector is fully normal conducting and brings the proton beam from the source through a 4-rod RFQ followed by a series of CH-type multigap cavities to 17 MeV. A MEBT line matches the beam into the main linac, which is fully superconducting and operated at 2K. 2 families of spoke cavities prepare the beam for final acceleration in a sequence of 5-cell elliptical cavities. The 600 MeV proton beam is then transported through an achromatic line for vertical injection from above into the reactor. A beam window centered in the subcritical core closes the line. A specific requirement for ADS application is the high level of the proton beam reliability, in other words the absence of unwanted beam trips. In the case of MYRRHA it is defined as follows: during a 3-months operational period the number of beam trips longer than 3s should be limited to 10. Shorter beam trips, on the other hand, are tolerated in large numbers. It has been acknowledged from the early design stage that such a level of availability/reliability clearly requires a coherent approach to all accelerator components, but also that it compels to implement a global fault tolerant concept. This has since been confirmed by extensive reliability modeling. The final design of the linac introduces the possibility of fault tolerance at the level of the superconducting cavities through conservative nominal conditions on beam dynamics and on cavity set points. A similar fault tolerant concept is applied in the solid state RF amplifiers, which may therefore continue feeding the accelerating cavities even in case of failing components. However, such a scheme, based on redundancy from modularity, may not be applied in the injector. Fault tolerance is then recovered by a mere duplication of the injector: 1 active, 1 hot standby. The phased approach of MYRRHA will primarily concentrate on its linac limited to 100 MeV (first spoke family), albeit with 1 injector only. This installation will be a relevantly sized test platform of various fault tolerance mechanisms, and thereby it will allow for a thorough investigation and extrapolation of the realistic capabilities of the full size 600 MeV linac.

News Article | May 4, 2017
Site: www.theengineer.co.uk

Industry and government are apparently in-step on the UK’s nuclear post-Brexit priorities, but will their concerns make it to the negotiating table? The government’s announcement that an exit from the EU also means an exit from Euratom – the body that regulates European nuclear trade and activity – has been causing consternation in the sector since it was announced in February’s “Brexit” white paper. These concerns reached fever pitch this week with the launch of three reports. They warn of the disastrous impact on the sector – such as by deterring international investment, derailing UK nuclear R&D, and potentially threatening the UK’s supply of energy – if Britain fails to devise a credible alternative by the time the UK leaves the EU. Perhaps the most strongly worded of these reports is “Exiting Euratom” published on Tuesday by the UK’s Nuclear Industry Association (NIA) – the trade body which represents companies operating in the UK’s civil nuclear sector. The paper sets out the priority areas for negotiations with the European Commission as the UK ceases to be a full member of the Euratom community, and outlines a series of steps government will need to take to enable the nuclear sector to continue its work with other countries within and outside the EU. These include replacing the Nuclear Co-operation Agreements (NCA) with key nuclear markets; agreeing a new funding arrangement for the UK’s involvement in European Union nuclear R&D, and generally maintaining confidence in the sector in order to secure critical investment. Warning that failure to ensure all of this is in place by the time Brexit negotiations conclude will be damaging for the sector Tom Greatrex, chief executive of the Nuclear Industry Association, said: “Without new arrangements in place by the time the UK leaves the Euratom community, there is scope for real and considerable disruption.” Nevertheless the report warns that replacing the mechanisms of EURATOM with an effective alternative in just 22 months will be exceptionally difficult. And it calls on the government to seek an agreement with the EU that existing arrangements will continue to apply until the process of agreeing new arrangements is concluded. Gratifyingly, these concerns are echoed by two separate government reports: one from the House of Lords Science & Technology Committee, and the other from the Business Energy and Industrial Strategy Committee. Both reports call on the government to delay its exit from Euratom and stress the need for government to work closely with industry on the development of a plan that preserves the essential benefits of Euratom membership. The BEIS committee report goes onto say that if energy policy strays too far from agreed European standards, the UK risks becoming a “dumping ground” for energy inefficient products. Few – if any – areas of UK industry have been spared the uncertainty prompted by last June’s referendum result, but the UK nuclear sector faces arguably one of the most complex and high stakes situations. A failure to secure a suitable replacement to Euratom could derail the UK’s nuclear ambitions, impact our energy supply and  – as we’ve previously written – put the UK at risk of losing its lead in fusion and other areas of nuclear research. If there’s cause for optimism, it’s that away from the posturing and “tough talk” of the Brexit negotiations there does appear to be a genuine consensus across industry and government that simply crashing out of Euratom is not an option. A failure to resolve these concerns constitute an act of industrial and economic vandalism. Let’s hope Britain’s “crack” team of Brexit negotiators are listening.

Ricci P.,EURATOM | Rogers B.N.,Dartmouth College
Physical Review Letters | Year: 2010

Plasma turbulence in a simple magnetized torus (SMT) is explored for the first time with three-dimensional global fluid simulations. Three turbulence regimes are described: an ideal interchange mode regime, a previously undiscovered resistive interchange mode regime, and a drift-wave regime. As the pitch of the field lines is decreased, the simulations exhibit a transition from the first regime to the second, while the third-the drift-wave regime-is likely accessible to the experiments only at very low collisionalities. © 2010 The American Physical Society.

Agency: GTR | Branch: EPSRC | Program: | Phase: Research Grant | Award Amount: 636.71K | Year: 2015

In a tokamak, the conditions for fusion energy are achieved by confining a hot plasma using a toroidal configuration of magnetic field. Thus, the magnetic field lines lie on a set of toroidal flux surfaces that are nested like a set of Russian dolls. All magnetic field lines on a given flux surface are usually equivalent and, specifically, all carry the same current. However, under certain situations this state can bifurcate to one where some field lines carry more current than others. This filamentation of the current density effectively tears the flux surface apart, creating a chain of so-called magnetic islands. The instability responsible for this is called a tearing mode. Such islands are detrimental to confinement, and therefore it is important to understand the physics of tearing modes. A particularly problematic instability is called the neoclassical tearing mode, or NTM. Small current filaments initially create small so-called seed islands. These seed islands reinforce the current filamentation, resulting in a positive feedback mechanism that causes the magnetic islands to grow extremely large. The degradation in confinement causes a drop in the core plasma pressure and a consequent loss in fusion power in a tokamak like ITER. However, this amplification mechanism is only observed when the initial seed island width exceeds a certain threshold of a few centimetres. Although we have ideas for the physics mechanisms that lie behind this threshold, there is no predictive quantitative model. This is largely because for small islands, the distribution of ions in both real and velocity space is important - a 6-dimensional problem. We have developed an expansion in the small ratio of the island width to system size that has enabled us to reduce the system to 4-dimensions - two spatial and two velocity components. Our initial studies indicate that this problem is tractable on modern high end computers, providing a predictive capability for the threshold for neoclassical tearing modes - a key ingredient for specifying the NTM control system on ITER, for example. In a second application of the theory, we are interested in a situation where the magnetic islands are induced by the tokamak operator. This is achieved by applying so-called resonant magnetic perturbations, or RMPs, to the plasma using a set of current-carrying coils. The motivation for this is to provide a control system for a repetitive sequence of tokamak plasma eruptions, called edge-localised modes, or ELMs. In an ELM, large filaments of plasma erupt from the surface in an event that is reminiscent of solar flares. We believe that these are driven by steep pressure gradients that form near the plasma edge. By driving small magnetic islands in this steep pressure gradient region with RMPs, it is expected that the pressure gradient can be reduced in a controlled way to just below that necessary to trigger an ELM. This is key for ITER, where uncontrolled ELMs will cause excessive erosion of its components at full fusion power. While the technique works on some tokamaks, it does not work on others. To understand this, we need improved models for how the plasma responds to magnetic islands that are driven externally - will it amplify them, as in the case of the NTM, or heal them? This understanding will help specify the ELM control system on ITER. We will develop a new high end computing code to calculate the kinetic plasma response to both natural and driven magnetic islands, using the model we have derived by an analytic reduction of the so-called drift-kinetic theory. Knowledge of the plasma response will enable us to quantify the current filamentation, and hence identify the conditions for which the plasma tends to amplify magnetic islands and when it heals them. We will work with experimentalists to design tests for our predictions against data from todays tokamaks, and make predictions for the requirements of the instability control systems on ITER.

Chapman I.T.,EURATOM
Plasma Physics and Controlled Fusion | Year: 2011

The sawtooth instability in tokamak plasmas results in a periodic reorganization of the core plasma. A typical sawtooth cycle consists of a quiescent period, during which the plasma density and temperature increase, followed by the growth of a helical magnetic perturbation, which in turn is followed by a rapid collapse of the central pressure. The stabilizing effects of fusion-born a particles are likely to lead to long sawtooth periods in burning plasmas. However, sawteeth with long quiescent periods have been observed to result in the early triggering of neo-classical tearing modes (NTMs) at low plasma pressure, which can, in turn, significantly degrade confinement. Consequently, recent experiments have identified various methods to deliberately control sawtooth oscillations in an attempt to avoid seeding NTMs whilst retaining the benefits of small, frequent sawteeth, such as the prevention of core impurity accumulation. Sawtooth control actuators include current drive schemes, such as electron cyclotron current drive, and tailoring the fast ion population in the plasma using neutral beam injection or ion cyclotron resonance heating. © 2011 IOP Publishing Ltd.

The recent progress in the experimental characterization of pedestal and ELM dynamics as well as in the insight into pedestal width scaling is reviewed. Various width scaling experiments from many devices indicate that the pedestal width scales weakly with the normalized ion Larmor radius and with the square root of the pedestal poloidal beta. The ELM onset in type I ELMy H-modes is consistently understood as an MHD stability limit on the maximum achievable edge pressure gradient. These results provide a prediction for the pedestal height in ITER. Time resolved measurements of pedestal parameters during the ELM cycle from various machines present a consistent picture of the pedestal dynamics, providing strong tests for pedestal models. Despite growing efforts in pedestal transport modelling, there is no consensus to date on what transport mechanism may explain the residual electron heat transport in the pedestal. As far as particle transport is concerned, a strong particle pinch may offset strong particle diffusion in the edge pedestal. Recent experiments have expanded the operational domains of the grassy ELM and QH-mode regimes and are consistent with predictions of the peeling-ballooning model. © 2010 IAEA, Vienna.

The effects of the fusion born β particles on the stability of the RWM are numerically investigated for one of the advanced steady state scenarios in ITER. The β contribution is found to be generally stabilizing, compared with the thermal particle kinetic contribution alone. The same conclusion is achieved following both a perturbative and selfconsistent approach. The latter generally predicts less stabilization than the former. At high enough plasma pressure, the self-consistent approach predicts two unstable branches for the ITER plasma studied here. The stabilizing effect from β particles is found to be generally weak, in particular in terms of the modification of the stability boundary. The effect is more pronounced only at fast enough plasma rotation frequency, roughly matching the β precession frequency, which is in the order of a few per cent of the toroidal Alfvén frequency for ITER. A simple, energy principle based, fishbone-like dispersion relation is proposed to gain a qualitative understanding of the numerical results. © 2010 IAEA, Vienna.

Installation of the ITER-like Wall (ILW) in JET, has allowed a direct comparison of operation with all carbon plasma facing components (PFCs) to an all metal beryllium/tungsten first-wall under otherwise nearly identical conditions. The JET results are compared with experience from ASDEX-Upgrade where there was a gradual change to a full tungsten first-wall over an extended period. The scope of this review ranges from experience with machine conditioning, impurities and breakdown to material migration, fuel retention, disruptions, impact on operational space, energy confinement and compatibility with impurity seeding. Significant changes are reported, not only in the physics directly related to plasma-surface interactions but also to the main plasma which is strongly affected in unexpected ways, impacting many aspects of tokamak operation. © 2013 Euratom. Published by Elsevier B.V. All rights reserved.

Agency: GTR | Branch: EPSRC | Program: | Phase: Fellowship | Award Amount: 668.05K | Year: 2015

If loaded a small amount, a metal will deform elastically, returning to its original shape when the load is removed. However if the load exceeds some value, then permanent deformation occurs, known as plasticity. Plasticity is far more complex to understand than elasticity as it involves breaking lines of atomic bonds in the metal. These lines of broken atomic bonds are called dislocations. This is analogous to the motion of a caterpillar: which does not attempt to move its whole body forward simultaneously; instead it incrementally moves its body forward in a wave of motion sweeping through the caterpillars body. Metals contains a huge number of dislocations: these lines sweep through the metal allowing atomic planes to slip over each over, causing the metal to be permanently deformed. When metal is loaded, new dislocations are nucleated and some become trapped at obstacles. However, if the load is applied too quickly or the metal is too cold, then the dislocation lines do not have time to nucleate and move: instead whole planes of atoms are ripped apart, fracturing the metal. In a nuclear reactor, the fuel rods are cladded in a zirconium alloy: over time, hydrogen from water used to cool the fuel rods, diffuses into the zirconium and is attracted to dislocation lines and to any small cracks or notches in the metal. If the hydrogen concentration becomes too high, hydrogen atoms will clump together to form precipitates which block dislocation motion and can easily fracture. It is this complex interaction between, dislocations, diffusion, precipitate formation and fracture which I aim to simulate on a computer. This is possible by utilising the power of modern graphics cards (developed to play video games) which allow massively parallel simulations to be performed easily and at little cost. Even then it is only possible to simulate a very small volume of material. Traditional mechanical tests (bending or compressing pieces of metal) were always performed on large specimens, several millimetres in size, meaning it was simply not possible to simulate all the dislocations in the sample explicitly. In the last decade it has become possible to perform mechanical tests on samples that are only a few microns in size. The samples are so small, that by utilizing the power of modern graphics cards, it will be possible to simulate the experiment including every dislocation in the material explicitly, and watch how they interact with each other and with multiple precipitates. Being able to simulate an entire experiment at this level of detail is unprecedented and it will provide new insights into the details of what exactly goes on when metal deforms plastically and fractures. The fundamental new insights gained during the project will be used to develop more accurate engineering design rules for industry and involves close collaboration with scientists and engineers at Lawrence Livermore National Laboratory in California, Imperial College London, Culham Centre for Fusion Energy in Oxfordshire, The National Physical Laboratory in Teddington and Rolls-Royce in Derby.

Agency: GTR | Branch: Innovate UK | Program: | Phase: Feasibility Study | Award Amount: 190.07K | Year: 2016

“I want to live in a vibrant community with easy access to work, leisure, family and entertainment and to my local towns and the countryside. I want to be independent and mobile in my old age. I want to live well and I want my great grandchildren to be able to live well too.” Technology will play a key role in delivering these aspirations. Connected autonomous vehicles will be part of the solution. Culham City is a new test site that will be used explore how smart technologies can improve how we live by enabling the safe and controlled testing of the next generation of transport solutions. In the process we will generate the evidence, to convince users, regulators, insurers and investors alike, that autonomous vehicles are a benefit to society. Culham City puts real people at the heart of CAV research and will create a world leading facility that will anchor CAV research in the UK for decades to come.

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