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•Modelling in preparation for future deuterium campaign.•The goal is to study tritium burn-up.•Modelling restricted to high energy neutrons.•Model for assessing Scintillating Fibre ...neutron detector diagnostics.•Detailed CAD based geometry based on unstructured mesh.
In this work, a Serpent 2 neutronics model of the Wendelstein 7-X (W7-X) stellarator is prepared, and an response function for the Scintillating-Fibre neutron detector (SciFi) is calculated using the model. The neutronics model includes the simplified geometry for the key components of the stellarator itself as well as the torus hall. The objective of the model is to assess the 14.1 MeV neutron flux from deuteron-triton fusions in W7-X, where the neutrons are modelled only until they have slowed down to 1 MeV energy. The key messages of this article are: demonstration of unstructured mesh geometry usage for stellarators, W7-X in particular; technical documentation of the model and first insights in fast neutron behaviour in W7-X, especially related to the SciFi: the model indicates that the superconducting coils are the strongest scatterers and block neutrons from large parts of the plasma. The back-scattering from e.g. massive steel support structures is found to be small. The SciFi will detect neutrons from an extended plasma volume in contrast to having an effective line-of-sight.
This paper explains how to obtain the distribution function of minority ions in tokamak plasmas using the Monte Carlo method. Since the emphasis is on energetic ions, the guiding-center ...transformation is outlined, including also the transformation of the collision operator. Even within the guiding-center formalism, the fast particle simulations can still be very CPU intensive and, therefore, we introduce the reader also to the world of high-performance computing. The paper is concluded with a few examples where the presented method has been applied.
Measuring fast ions, most notably fusion alphas, in ITER and future reactors remains an issue that still lacks an adequate solution. Numerical simulations are invaluable in testing the potential and ...limitations of various proposed diagnostics. However, the validity of the numerical tools first has to be checked against results from existing tokamaks. In this contribution, various synthetic diagnostics for fast ions (collective Thomson scattering, neutral particle analyzer, neutron camera, infrared measurements, fast ion loss detector, and activation probe) from the orbit-following Monte Carlo code ASCOT are compared to measurements from several tokamaks (ASDEX Upgrade, DIII-D, and JET). Within the limitations of the physics included in the numerical model and availability of input data from experiments, the agreement between synthetic data and measurements is found to be quite good.
Nuclear energy policy is in turmoil in many Western European countries after the Fukushima accident in March 2011. We review the nuclear energy policies in European countries with emphasis on recent ...changes. Differences in the energy policies of different EU country groups have become more pronounced, contrary to the EU goal of “speaking with one voice” in energy issues. Since the beginning of European and US electricity market liberalisation in the 1990s, it has often been claimed that nuclear power is not competitive in liberalised electricity markets. We challenge this statement with the example of Finland, which is part of the liberalised Nordic market since the mid-1990s. One nuclear plant is currently under construction and two new nuclear power plants, out of three applications, were recently approved by the Finnish Parliament. The retirement of existing fossil fuel plants and old nuclear power plants will cause increased net import needs, which is in contradiction with the Government targets. By the year 2030, the need for additional new capacity will be 6 GW. This situation is by no means unique to Finland, but rather is set to emerge throughout Europe.
► EU long-term climate policies and recent nuclear policy actions in some member states are in striking contrast. ► Fukushima strengthened polarisation in the national nuclear policies between EU country groups. ► Finnish industry sees constructing nuclear power as economically attractive at the liberalised Nordic electricity market. ► In addition to 4.8 GW of new nuclear capacity, further need will be 6 GW in Finland by 2030.
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•Implemented a combined FEM Biot-Savart law method to calculate ITER magnetic fields.•Detailed ITER 3D magnetic fields, with ferromagnetic components.•Calculated also the vector ...potential and Fourier components.•Final result useful for particle orbit following even unsmoothed.
The magnetic perturbation due to the ferromagnetic test blanket modules (TBMs) may deteriorate fast ion confinement in ITER. This effect must be quantified by numerical studies in 3D. We have implemented a combined finite element method (FEM) – Biot-Savart law integrator method (BSLIM) to calculate the ITER 3D magnetic field and vector potential in detail. Unavoidable geometry simplifications changed the mass of the TBMs and ferritic inserts (FIs) up to 26%. This has been compensated for by modifying the nonlinear ferromagnetic material properties accordingly. Despite the simplifications, the computation geometry and the calculated fields are highly detailed. The combination of careful FEM mesh design and using BSLIM enables the use of the fields unsmoothed for particle orbit-following simulations. The magnetic field was found to agree with earlier calculations and revealed finer details. The vector potential is intended to serve as input for plasma shielding calculations.
The Monte Carlo guiding center (GC)-following code ASCOT has been upgraded with the full-orbit-following capability. This is utilized only near the vessel walls in order to simulate diagnostics with ...characteristic lengths on the order of the Larmor radius. The option to switch more generally, near the turning points of the particle, from the GC integration to full-orbit integration and back is also discussed.
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