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在线同位素分离系统(以下简称ISOL系统)与HI-13串列加速器存在一条束流管道将两个区域联通。束流管道需要通过串列加速器大厅的西墙,在串列加速器运行期间产生的中子会通过穿墙管道泄漏到串列升级工程大楼中的监督区内,导致中子剂量率超过设计标准。所以需要对穿墙管道进行局部屏蔽设计,以保证该区域的剂量率满足设计要求。屏蔽设计的源项为:24 MeV/8μA的氘束轰击法拉第筒内的1 mm厚的钼片及10 mm厚的铜靶片,归一到单个入射粒子的中子产额为4.49×10-3/d,出射中子能谱及角分布示于图1、2。源项的位置为串列加速器高能端法拉第筒,位置见图3;源项的高度为串列加速器大厅地面以上1.75 m处。
The online isotope separation system (hereinafter referred to as ISOL system) and the HI-13 Tandem Accelerator there is a pipeline to connect the two regions. The beam pipe needs to pass through the west wall of the tandem accelerator hall and neutrons generated during the tandem accelerator’s run through the wall-to-wall leaks into the supervision area in the tandem upgrade building, resulting in the neutron dose rate exceeding the design criteria. Therefore, we need to design a partial shield on the wall-penetrating pipe to ensure that the dose rate in this area meets the design requirements. The source of the shielding design is: a deuterium beam of 24 MeV / 8μA is bombarded with a 1 mm thick molybdenum sheet and a 10 mm thick copper target sheet in a Faraday cup. The neutron yield normalized to a single incident particle is 4.49 × 10- 3 / d, exiting neutron spectrum and angular distribution shown in Figure 1,2. The location of the source item is the tandem accelerator high-energy end Faraday cage at the location shown in Figure 3; the height of the source term is 1.75 m above the ground of the tandem accelerator hall.