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 aspeaking with one voicea 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.
In the present paper, we propose an alternative, based on constructivism, to the conventional way of teaching basic physics courses at the university level. We call this approach 'coherent teaching' ...and the underlying philosophy of teaching science and engineering 'need-based learning'. We have been applying this philosophy in practice in a basic physics course at the Department of Engineering Physics and Mathematics of Helsinki University of Technology. Here we present the main ideas of the new approach and how we have implemented them, as well as discuss how coherent teaching has affected the students' opinions about the course and how it has changed the learning results.
Neutron production rates in fusion devices are determined not only by the kinetic profiles but also the fast ion slowing-down distributions. In this work, we investigate the effect of magnetic ...configuration on neutron production rates in future deuterium plasmas in the Wendelstein 7-X (W7-X) stellarator. The neutral beam injection, beam and triton slowing-down distributions, and the fusion reactivity are simulated with the ASCOT suite of codes. The results indicate that the magnetic configuration has only a small effect on the production of 2.45 MeV neutrons from thermonuclear and beam-target fusion. The 14.1 MeV neutron production rates were found to be between \(1.49 \times 10^{12}\) \(\mathrm{s}^{-1}\) and \(1.67 \times 10^{12}\) \(\mathrm{s}^{-1}\), which is estimated to be sufficient for a time-resolved detection using a scintillating fiber detector, although only in high-performance discharges.
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, a variety of 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 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.
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 contribution documents the methods used in the BioSaw code. The code is inteded to be a flexible tool for calculating magnetic fields due to coils in magnetic confinement fusion devices. It ...assumes the conductors are infinitesimally thin and can be described as either point sequences or circular coils. The code can calculate both the magnetic field as well as the vector potential due to the coils. The fields can be reduced very near the coils to avoid singular behaviour caused by the thin conductor approximation.
We present a novel implementation of a Monte Carlo particle-following code for solving the distribution function of minority species in fusion plasmas, called ASCOT5, and verify it using theoretical ...results for neoclassical transport. The code has been developed from ground up with an OpenMP-MPI hybrid paradigm to take full advantage of current and next generation many-core CPUs with multithreading and SIMD operations. Up to 6-fold increase in performance is demonstrated compared to a previous version of the code which only utilizes MPI. The physics model of the code is comprehensively validated against existing theoretical work, and it is shown to faithfully reproduce neoclassical diffusion across three different collisionality regimes. In simulations for realistic tokamak plasmas, including complex non-axisymmetric geometry, ASCOT5 is verified to reproduce results from the previous version ASCOT4.
Using the orbit-following code ASCOT, we model alpha particle transport in ITER under the influence of ELM control coils (ECCs), toroidal field ripple, and test blanket modules, with emphasis on how ...the plasma response (PR) modifies the transport mechanisms and fast ion loads on the divertor. We found that while PR shields the plasma by healing broken flux surfaces, it also opens a new loss channel for marginally trapped particles: PR causes strong toroidal variation of the poloidal field near the X-point which leads to de-localisation of banana tips and collisionless transport. The reduction in passing particle losses and the increase in marginally trapped particle losses shift divertor loads from targets to the dome and under-the-dome structures. The plasma response was calculated by both MARS-F and JOREK codes. The new transport mechanism was stronger for PR calculated by JOREK which, unlike MARS-F, explicitly includes the X-point.
The activation probe is a robust tool to measure flux of fusion products from a magnetically confined plasma. A carefully chosen solid sample is exposed to the flux, and the impinging ions transmute ...the material making it radioactive. Ultra-low level gamma-ray spectroscopy is used post mortem to measure the activity and, thus, the number of fusion products. This contribution presents the numerical analysis of the first measurement in the ASDEX Upgrade tokamak, which was also the first experiment to measure a single discharge. The ASCOT suite of codes was used to perform adjoint/reverse Monte Carlo calculations of the fusion products. The analysis facilitates, for the first time, a comparison of numerical and experimental values for absolutely calibrated flux. The results agree to within a factor of about two, which can be considered a quite good result considering the fact that all features of the plasma cannot be accounted in the simulations. Also an alternative to the present probe orientation was studied. The results suggest that a better optimized orientation could measure the flux from a significantly larger part of the plasma.
