Abstract The anticipated heat flux limit of the European DEMO first wall is ∼1−2 MW/m2. During transient and off normal events, the heat load deposited on the wall would be much larger than the steady state heat load and exceed the first wall limit, therefore the breeding blanket first wall needs to be protected. This involves dedicated discrete limiters in certain regions of the machine that would take the brunt of the heat load as well as adequate shaping of the first wall. The current concept envisages limiters at a few (3–4) equatorial ports to cope with the ramp-up of the plasma; upper limiters (in ∼8 upper ports) are considered for upward vertical displacement events. Two design options have been considered for these limiters: a modular design where the limiter plasma facing components are attached to individual plates that are assembled together so that transient electromagnetic loads can be reduced, and in case of damage the plates can be replaced/repaired individually; and a divertor-like design where the plasma facing components are attached to a single Eurofer cassette. Other limiters considered include inner wall limiters in case of plasma contraction and lower limiters may be needed for downward vertical displacement events. The thermal hydraulic finite element analysis results show that the integrity of the cooling pipes can be maintained during the anticipated transient events. The limiters are considered to be sacrificial and designed to be replaceable independently from the breeding blanket system. The design has to allow that installation, removal or replacement of the limiters can be performed remotely. Strategy to tackle outstanding issues and required R&D is also discussed.

中文翻译：

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欧洲DEMO首创壁面成型及限位器设计分析现状

摘要 欧洲 DEMO 第一壁的预期热通量限制为 ~1-2 MW/m2。在瞬态和非正常事件期间，沉积在壁上的热负荷将远大于稳态热负荷并超过第一壁限制，因此需要保护繁殖毯第一壁。这涉及机器某些区域中的专用离散限制器，这些限制器将首当其冲地承受热负荷以及第一壁的适当成形。当前的概念设想在几个 (3-4) 赤道端口处设置限制器，以应对等离子体的上升；对于向上的垂直位移事件，考虑使用上限器（在~8 个上端口）。这些限制器考虑了两种设计方案：模块化设计，其中限幅器面向等离子体的组件连接到组装在一起的单个板，从而可以减少瞬态电磁负载，并且在损坏的情况下，可以单独更换/修复板；以及类似偏滤器的设计，其中面向等离子的组件连接到单个 Eurofer 盒式磁带。考虑的其他限制器包括在等离子体收缩的情况下的内壁限制器和向下垂直位移事件可能需要下限器。热工水力有限元分析结果表明，在预期的瞬态事件期间可以保持冷却管道的完整性。限制器被认为是牺牲性的，并且设计为可独立于繁殖毯系统进行更换。设计必须允许安装，可以远程移除或更换限制器。还讨论了解决悬而未决问题和所需研发的战略。