Engineering challenges for accelerated fusion demonstrators

Abstract

There are several programmes within the fusion community that are engaged in the design of fusion devices to follow the International Thermonuclear Experimental Reactor (ITER), referred to as ‘demonstrators’. These programmes have identified many issues over the past decade, and research now concentrates on optimizing the combination of systems against a set of Key Performance Indicators (KPI) which may vary between programmes. While the return on investment in and experience from ITER is seen as an important factor in this research there are significant differences in the operational conditions and KPI of demonstrators that generate additional problems requiring different solutions. Among these problems are the necessary use of uncommon materials for structural and functional purposes, the impact of the availability KPI on basic machine design, configuration and component lifetime and the integration of the tritium fuel and thermodynamic cycles. These raise issues of component manufacture and standards and of resource availability in the required quantities and quality that are independent of device size and design. Interpreting ‘accelerating fusion’ in a wider sense, the impact of these issues, analysed in respect of developmental timescales, shows that a strategy of early engagement with the industrial supply chain and the development of computational engineering testing and verification will be essential to prevent prolonged timescales to fusion progress. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’

Effects of stress triaxiality and strain rate on the fracture of a CuCrZr alloy

“…The chemical compositions of the 10 mm and 25 mm CuCrZr rods are Cu-0.84Cr-0.08Zr and Cu-0.7Cr-0.13Zr (all in wt.%) respectively. Both materials meet the requirements of the ITER grade CuCrZr composition (0.6-0.9Cr% and 0.07-0.15Zr%, all in wt%) [6]. It is well-known that the mechanical properties of CuCrZr are significantly affected by thermo-mechanical processes [7,24].…”

“…The divertor components are cooled using pressurised water and operate in extreme environments including high temperature, irradiation and cyclic multi-axial thermal and mechanical loads [5][6]. To develop the DEMO Design Criteria for In-vessel Components (DDC-IC), the development of the CuCrZr material property handbook (MPH) is also required [7].…”

Re-examining the role of nuclear fusion in a renewables-based energy mix

“…Even after developing a demonstration reactor, the adoption of fusion plants must experience the so-called "valley of death" in which early plants have high capital costs and long build times, whilst not yet providing the optimised return on investment which would finance innovation [25]. This will be exacerbated by the challenges of developing new supply chains [26].…”

Can the development of fusion energy be accelerated? An introduction to the proceedings

“…Elizabeth Surrey's paper [38] concentrates on the engineering challenges of accelerated demonstrator systems relevant to a fusion power plant. A detailed discussion is given of the component systems relevant to a fusion power plant.…”