• Energy Research

Abstract Conceptual design activities of the first fusion power plants were launched in recent years with a view to putting them into operation by 2050. Nuclear fusion offers significant benefits in comparison with exploited energy sources, especially limitless fuel reserves, inherent nuclear safety, and negligible impact on the environment. The challenge is a high heat and neutron loading of the fusion reactors nuclear zone. The paper brings the ex-ante economic analysis of the fusion power plant model DEMO2 in terms of the cost of electricity. The model investment and operating costs are presented. The limit sales price of electricity was found using the net present value method. The levelized cost of electricity LCOE method with the inclusion of external costs is used for a comparison of selected power plant types based on the OECD statistical data and the EU ExternE project results. The comparison shows the levelized cost of electricity of fusion power plants competitive to the actual renewable resources. After internalisation of external costs, the fusion power plants should become even the second cheapest power source.

Abstract Conceptual design activities of the first fusion power plants were launched in recent years with a view to putting them into operation by 2050. Nuclear fusion offers significant benefits in comparison with exploited energy sources, especially limitless fuel reserves, inherent nuclear safety, and negligible impact on the environment. The challenge is a high heat and neutron loading of the fusion reactors nuclear zone. The paper brings the ex-ante economic analysis of the fusion power plant model DEMO2 in terms of the cost of electricity. The model investment and operating costs are presented. The limit sales price of electricity was found using the net present value method. The levelized cost of electricity LCOE method with the inclusion of external costs is used for a comparison of selected power plant types based on the OECD statistical data and the EU ExternE project results. The comparison shows the levelized cost of electricity of fusion power plants competitive to the actual renewable resources. After internalisation of external costs, the fusion power plants should become even the second cheapest power source.

AbstractIf the decision is made not to apply a toroidal chamfer to tungsten monoblocks at ITER divertor vertical targets, exposed leading edges will arise as a result of assembly tolerances between adjacent plasma-facing components. Then, the advantage of glancing magnetic field angles for spreading plasma heat flux on top surfaces is lost at the misaligned edges with an interaction occurring at near normal incidence, which can drive melting for the expected inter-ELM heat fluxes. A dedicated experiment has been performed on the COMPASS tokamak to thoroughly study power deposition on misaligned edges using inner-wall limited discharges on a special graphite tile presenting gaps and leading edges directly viewed by a high resolution infra-red camera. The parallel power flux deducted from the unperturbed measurement far from the gap is fully consistent with the observed temperature increase at the leading edge, respecting the power balance. All the power flowing into the gap is deposited at the leading edge and no mitigation factor is required to explain the thermal response. Particle-in-cell simulations show that the ion Larmor smoothing effect is weak and that the power deposition on misaligned edges is well described by the optical approximation because of an electron dominated regime associated with non-ambipolar parallel current flow.

AbstractIf the decision is made not to apply a toroidal chamfer to tungsten monoblocks at ITER divertor vertical targets, exposed leading edges will arise as a result of assembly tolerances between adjacent plasma-facing components. Then, the advantage of glancing magnetic field angles for spreading plasma heat flux on top surfaces is lost at the misaligned edges with an interaction occurring at near normal incidence, which can drive melting for the expected inter-ELM heat fluxes. A dedicated experiment has been performed on the COMPASS tokamak to thoroughly study power deposition on misaligned edges using inner-wall limited discharges on a special graphite tile presenting gaps and leading edges directly viewed by a high resolution infra-red camera. The parallel power flux deducted from the unperturbed measurement far from the gap is fully consistent with the observed temperature increase at the leading edge, respecting the power balance. All the power flowing into the gap is deposited at the leading edge and no mitigation factor is required to explain the thermal response. Particle-in-cell simulations show that the ion Larmor smoothing effect is weak and that the power deposition on misaligned edges is well described by the optical approximation because of an electron dominated regime associated with non-ambipolar parallel current flow.

Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n = 2 RMP maintaining good confinement HH(98, y2) 0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.