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Highlights • FEM analysis is performed to evaluate stresses at the geometries of FW cooling channels which can handle two different types of heat fluxes using water as a coolant. • For handling normal heat fluxes round tubes with countercurrent flow are chosen while for handling enhanced heat fluxes channel with the hypervapotron configuration is chosen. • The countercurrent flow cooling channels were able to withstand heat flux 1.7 MW/m2 and 15.0 MPa pressure inside the tubes. • The hypervapotron geometry needs further optimization to withstand required heat flux and pressure. Abstract The European DEMOnstration (DEMO) reactor precedes the development of the fully commercial fusion power plant. One of the key components of the DEMO is the first wall (FW). The FW is acted upon by extreme particle and radiation loads, which results in high heat fluxes varying across the reactor vessel. This paper attempts to evaluate two DEMO FW water cooling concepts from the stress point of view. The heat sink material chosen for the FW is Eurofer97 with thermal conductivity of ∼28 W/mK at 20 °C; the cooling conditions opted are those of pressurized water reactor (PWR), i.e. 285 °C and 15.5 MPa. In the present work it is attempted to perform the stress analysis of the two different heat sink channel configurations, these are circular pipes with countercurrent flow and channel with hypervapotron configuration. The thermo-hydraulic optimization of these components has been performed in one of the author's previous work. The stress in the components is caused by the pressure of the fluid and increase in the temperature of the material. To accomplish the work, commercial finite element method software ANSYS is used. In a case of unsatisfactory results, further recommendations are given. Simulations are performed with P91, which is material being commonly used in power engineering and will be also used for manufacturing of the discussed configuration of DEMO FW mock-ups which will be afterwards tested in high heat flux facility HELCZA. [ABSTRACT FROM AUTHOR]

Abstract: Helium-cooled reactors offer several important advantages as the helium is an inert and neutron transparent gas, compatible with high outlet temperatures and all structural and functional materials considered for plasma facing components. On the other hand, during the power plant studies performed up to now it became evident, that the helium pumping power could become very high if standard cooling methods based on hydraulically smooth cooling channels would be applied and that a very high heat flux in the divertor can only be achieved when using sophisticated gas cooling methods. In relation to this the main focus in this paper is on advanced gas cooling technology applications developed at Forschungszentrum Karlsruhe (FZK) for the main in-vessel components blanket/first wall and divertor of future fusion power reactors. Among a large number of considered cooling technologies the V-rib-based surface roughness approach for the first wall and the multiple jet impingement cooling technique for the divertor were identified as suitable and advantageous methods. The paper presents the main parameters to be considered and an evaluation of the achievable cooling performance in both cases. [Copyright &y& Elsevier]

Abstract: A present topic of high interest in magnetic fusion is the “gap” between near-term and long-term concepts for high heat flux components (HHFC), and in particular for divertors. This paper focuses on this issue with the aim of characterizing the international status of current HHFC design concepts for ITER and describing the different technologies needed in the designs being developed for fusion power plants. Critical material and physics aspects are highlighted while evaluating the current readiness level of long-term concepts, identifying the design and R&D gaps, and discussing ways to bridge them. [Copyright &y& Elsevier]