串列升级工程ISOL系统需3根300kV直流高压穿墙管,它们安装在强辐射区,要求其既能在强辐射环境下工作,结构材料又有较低的中子活化截面,以便必要时维护。为降低中子沿穿墙孔道的泄漏,要求穿墙管结构紧凑,中子泄漏通道尽可能小。根据以上要求,设计了双层套管式穿墙 Serial upgrade project ISOL system to be three 300kV DC high voltage through wall tube, they are installed in a strong radiation area, requiring both in a strong radiation environment, structural materials have a lower neutron activation cross section, so as to maintain . In order to reduce the leakage of neutrons along the perforation of the wall, it is required that the wall pipe be compact in structure and the neutron leakage passage should be as small as possible. According to the above requirements, the design of double casing through wall