Abstract
Abstract In a demonstrational fusion power plant (DEMO), divertor is supposed to protect vacuum vessel and superconducting magnets against neutron flux in the bottom region of the vessel. The vessel is subject to a strict design limit in irradiation damage dose and the magnets in nuclear heating power, respectively. Thus, the DEMO divertor must have the capability to protect sufficiently the vessel and the magnets against neutron flux being substantially stronger than in ITER. In this paper, a first systematic neutronics study for the European DEMO divertor is reported. Results of the extensive assessment of key nuclear loading features (nuclear heating, irradiation damage & helium production) are presented for two optional concepts, namely, dome and shielding liner including minor geometrical variants. The shielding performance of the two competing design options is discussed together with the case of a bare cassette (no shielding), particularly in terms of damage dose compared with the design limits specified for the European DEMO. It was found that both the dome and shielding liner were able to significantly reduce the nuclear loads in the cassette body and the vessel. The maximum damage dose at the end of the lifetime remained subcritical for the cassette body for both cases whereas it exceeded the limit for the vessel under the dome, but only locally on the surface underneath the pumping duct. But, the damage could be reduced below the limit for the vessel by increasing the size of the dome or by deploying the shielding liner. The most critical feature was the excessive damage occurring in the own body of the shielding components where the maximum damage dose in the steel heat sink of the dome and the shielding liner far exceeded the design limit at the end of the lifetime.
Highlights
Being in charge of critical operational functions such as removal of ash and impurity particles and exhaust of thermal power from plasma, the divertor is one of the most important in-vessel components in a fusion reactor [1,2]
The shielding performance of the two competing design options is discussed together with the case of a bare cassette, in terms of damage dose compared with the design limits specified for the European demonstrational fusion power plant (DEMO)
In a fusion power plant, such as demonstrational fusion reactor (DEMO), a divertor system will be subjected to extremely harsh loading environment characterized by high heat fluxes, particle bombardment, electromagnetic forces and neutron fluxes [5,6,7]
Summary
Being in charge of critical operational functions such as removal of ash and impurity particles and (partial) exhaust of thermal power from plasma, the divertor is one of the most important in-vessel components in a fusion reactor [1,2]. In a fusion power plant, such as demonstrational fusion reactor (DEMO), a divertor system will be subjected to extremely harsh loading environment characterized by high heat fluxes, particle bombardment, electromagnetic forces and neutron fluxes [5,6,7]. Further detrimental effects are thermal softening and thermal stresses of structural materials due to volumetric nuclear heating by gamma ray production [14,15]. In such a circumstance, powerful active cooling is needed at the cost of design complication [16,17]. Extensive nuclear loading features (nuclear heating, material damage and helium production) were investigated for two competing shielding concepts (dome vs shielding liner). Revision of the CAD model is currently ongoing [22], but the essential features of nuclear loading presented in this paper should be still indicative
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
