EAST托卡马克装置的核辐射监测系统

Radiation monitoring system for EAST tokamak

EAST(Experimental Advanced Superconducting Tokamak)现阶段D-D运行产生2.45 Me V聚变中子及次级核反应γ射线,为了解EAST运行期间辐射场的分布及强度,确保运行期间人员及环境的核辐射安全。针对EAST运行期间装置大厅内部存在较强的中子、伽马瞬变辐射场的特征,结合环境低本底辐射监测的需要,采用宽动态范围、快时间响应的场所辐射监测探测器,与高灵敏度、稳定性好的环境辐射监测探测器相结合的方式,围绕EAST装置布置13个辐射监测点,每点分别安装一台中子、伽马监测器。采用自行编写的Lab VIEW辐射监测软件进行数据采集,组建了一套EAST托卡马克装置的中子、伽马辐射剂量监测系统。该系统在2015年春季EAST实验中连续稳定运行了三个月,可靠性较高,获取了大量实验数据。监测系统满足EAST核辐射监测的要求,同时为后续开展聚变堆辐射安全与防护研究提供实验平台。

Background：During the experiment of Experimental Advanced Superconducting Tokamak （EAST）, reaction of D-D may generate neutrons with energy of 2.45 MeV, and bremsstrahlung gamma rays and neutron activated gamma rays as well.Purpose：The aim is tostudy the radiation of neutrons and gamma rays in the EAST hall during the running of EAST tokamak and obtain the radiation doses under different modes and parameters by implementing a radiation monitoring system to diagnose some plasma parameters and ensure the radiation safety of the personnel and the environment around EAST.Methods：In consideration of the highly and transient radiation doses of neutrons and gamma rays contrast to the lowly environmental background during the plasma discharge in the EAST hall, the combination of high ranging and fast responding detectors are adopted in the EAST hall whilst high sensitivity and stability detectors are deployed in the environment. Thirteen monitoring points were selected around the EAST, each point contains a neutron detector and a gamma ray detector. Combination of Ethernet and twisted pair are adopted for the data transmission, and the radiation monitoring software based on LabVIEW was developed. Results：A radiation monitoring system of EAST tokamak was successfully built to monitor and save the real-time radiation dose rates of each detector, and to produce an alarm signal when abnormal dose rate happens. The radiation monitoring system had run stably for more than three months during the EAST experiment in the spring of 2015, and obtained many useful experimental data on fusion radiation safety and protection.Conclusion：The radiation monitoring system can well monitor the radiation around the EAST tokamak, and provide a platform for the future study of radiation safety and protection of the fusion reactor.