Neutronics assessments of LHCD antenna system for CFETR

To maintain a long-duration plasma current and obtain steady-state operation for CFETR, a non-inductive Heating and Current Drive (H&CD) system is currently under study. Lower Hybrid Current Drive (LHCD) is an important auxiliary heating system, that has good current drive efficiency and improves plasma confinement by changing the current distribution.Neutronics calculation was conducted to study the nuclear performance and shielding effectiveness. This study was performed on a CFETR 22.5◦ model integrated with an upper-port LHCD antenna structure. The detailed 3D neutronics model was built using the computer-aided modeling platform cosVMPT, and particle transport was performed using MCNP5 with the nuclear data library FENDL-2.1. With the support of high performance variance reduction technique, “on-the-fly” GVR method, global neutron and photon flux distributions with reasonable relative error were obtained. The irradiation damage to components in the antenna system was assessed, including DPA, gas production and nuclear heat density. The total nuclear heat for the transmission structure was 1.192 MW, and the peak irradiation damage was located at the front end of the Passive-Active Multi-junction (PAM) launcher. Owing to the blanket opening for wave propagation, the induced nuclear responses for VV and TFC were analyzed, and the shielding design was initialized. The results showed that all the parameters were within the design limit after the shielding design. Because part of the blanket module was occupied by the antenna launcher, the TBR of CFETR was evaluated, and it decreased by only 0.22% for the whole fusion reactor.

为实现中国聚变工程试验堆（CFETR）的长时等离子体电流维持与稳态运行目标，当前正研究非感应加热与电流驱动（H&CD）系统。低杂波电流驱动（LHCD）作为重要的辅助加热系统，具备优异的电流驱动效率，可通过改变电流分布改善等离子体约束性能。本研究针对集成了上端口LHCD天线结构的CFETR 22.5°模型开展中子学计算，以分析其核性能与屏蔽效能。详细的三维中子学模型基于计算机辅助建模平台cosVMPT构建，粒子输运计算采用MCNP5程序与核数据库FENDL-2.1。借助高性能方差缩减技术与"on-the-fly" GVR方法，最终获得了相对误差合理的全局中子与光子通量分布。本研究对天线系统内的部件开展了辐照损伤评估，涵盖位移损伤剂量（DPA）、气体产额与核热密度等指标。传输结构的总核热为1.192 MW，峰值辐照损伤位于无源-有源多结（PAM）发射天线的前端。由于包层预留了波传播通道，本研究分析了真空室（VV）与环向场线圈（TFC）的感生核响应，并启动了初始屏蔽设计。结果显示，经屏蔽设计优化后，所有参数均满足设计限值要求。因部分包层模块被天线发射装置占用，本研究对CFETR的氚增殖比（TBR）进行了评估，结果显示整个聚变反应堆的氚增殖比仅下降了0.22%。