The pre-concept design of the DEMO Vacuum Vessel is going on in view of the 2020 gate review; moreover the nuclear heat loads on the vessel inner shell were determined and found to be about one order of magnitude higher compared to ITER. A subsequent thermal-structural analysis of the vessel inner shell revealed high thermal stresses and a large temperature gradient through the inner shell thickness. Given the simultaneous occurrence of primary membrane stresses in the entire vessel inboard wall and, in proximity of the vessel ribs, high bending stresses due to the coolant pressure, a survey of all options within the design rules was required to identify the inter-dependencies of the individual stress limits (primary membrane, primary bending, thermal membrane plus bending). In order to face this kind of issues a detailed assessment on the design of the inboard wall of DEMO Vacuum Vessel has been conducted and is presented here. The current work evaluates both P and S type damages for the inboard wall of DEMO Vacuum Vessel in case of high nuclear heat load, vacuum vessel coolant pressure and toroidal field coil fast discharge. The elastic analysis method has been used to check the rules for prevention of both types of damage. The rules applied to prevent the aforementioned damages are compliant to Level A criteria, in case of negligible creep and negligible irradiation. In order to check the structural integrity of the inboard wall of DEMO VV against high thermal and mechanical loads, optimization structural analyses were performed and checked against the rules provided in the applicable design code (RCC MRx).

中文翻译：

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欧洲DEMO真空容器内壁设计

鉴于2020年门检，DEMO真空容器的预概念设计正在进行中；此外，还确定了容器内壳上的核热负荷，发现其比 ITER 大约高一个数量级。随后对容器内壳的热结构分析显示，内壳厚度内存在高热应力和大温度梯度。鉴于整个容器内壁同时出现主膜应力，并且在容器肋附近，由于冷却剂压力而产生高弯曲应力，因此需要对设计规则中的所有选项进行调查，以确定各个应力限制（主膜、主弯曲、热膜加弯曲）。为了应对此类问题，我们对 DEMO 真空容器内壁的设计进行了详细评估，并在此介绍。目前的工作评估了 DEMO 真空容器内壁在高核热负荷、真空容器冷却剂压力和环形磁场线圈快速放电的情况下的 P 型和 S 型损坏。弹性分析方法已用于检查预防这两种类型损坏的规则。在蠕变和辐射可忽略不计的情况下，用于防止上述损坏的规则符合 A 级标准。为了检查 DEMO VV 内壁在高热负荷和机械负荷下的结构完整性，进行了优化结构分析，并根据适用的设计规范 (RCC MRx) 中提供的规则进行了检查。