Abstract Within the EUROfusion Power Plant Physics and Technology Department the DEMOnstrational fusion power plant (DEMO) is being developed. One of the fundamental challenges is the integration of ports in the vacuum vessel. The lower port of the DEMO machine is particularly challenging due to tight space constraints imposed by the toroidal field (TF) coils and the requirement to provide a large open duct through both the divertor and inside the port to enable for vacuum pumping. In addition, feeding pipes of divertor and tritium breeding blanket need to be integrated and access space must be provided for various remote handling operations. Several neutronics requirements need to be fulfilled, e.g. the nuclear heating of the superconducting TF coils and the gamma radiation levels inside the cryostat need to be limited to reduce occupational exposure to personnel during maintenance, and the irradiation damage and neutron heating in different components need to be considered in the design and limited. The results of neutronic analyses show that further shielding optimization is needed as maximum TF coil heating is still 5× the design limit and the SDDR values orders of magnitude above the target values inside the lower port duct. With this in mind the direction of future design developments is discussed.

中文翻译：

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DEMO 下远程处理和泵送端口的屏蔽概念和中子评估

摘要 在 EUROfusion 发电厂物理和技术部，正在开发 DEMOnstrational 聚变发电厂 (DEMO)。基本挑战之一是真空容器中端口的集成。由于环形场 (TF) 线圈对空间的严格限制，以及需要提供穿过偏滤器和端口内部的大型开放管道以实现真空泵送，DEMO 机器的下端口特别具有挑战性。另外，偏滤器和氚育种毯的进料管需要整合，并且必须为各种远程处理操作提供出入空间。需要满足几个中子学要求，例如 超导挠场线圈的核加热和低温恒温器内部的伽马辐射水平需要限制，以减少维护期间人员的职业暴露，并且在设计时需要考虑和限制不同部件的辐照损伤和中子加热。中子分析的结果表明，需要进一步的屏蔽优化，因为最大 TF 线圈加热仍然是设计极限的 5 倍，并且 SDDR 值比下端口管道内的目标值高出几个数量级。考虑到这一点，讨论了未来设计发展的方向。中子分析的结果表明，需要进一步的屏蔽优化，因为最大 TF 线圈加热仍然是设计极限的 5 倍，并且 SDDR 值比下端口管道内的目标值高出几个数量级。考虑到这一点，讨论了未来设计发展的方向。中子分析的结果表明，需要进一步的屏蔽优化，因为最大 TF 线圈加热仍然是设计极限的 5 倍，并且 SDDR 值比下端口管道内的目标值高出几个数量级。考虑到这一点，讨论了未来设计发展的方向。