Induced Radioactivity Study Of Particle Accelerator

The induced radioactivity of particle accelerators is an essential part of accelerator radiation protection.It’s necessary to study the induced radioactivity in the design,operation and decommissioning of particle accelerators.These research results are all important data for particle accelerator radiation protection and are of great significance to accelerator design and operation.The research content of this paper mainly includes two aspects: radionuclide activity and residual dose rate.The research methods include theoretical calculations,experimental studies,and Monte Carlo simulations.And the subjects included components of accelerator,dust outside enclosure,air in the experimental terminal and cooling water.The experimental study of induced radioactivity was conducted at the Lanzhou Heavy Ion Research Facility(HIRFL).The induced radioactivity of SFC electrostatic deflection plates and accelerator cooling water was investigated based on the high purity germanium γ spectrometer.The long-lived radionuclides with the half-life more than 70 days produced in the high voltage electrode,the cutting board and the lateral dust of the deflecting plate had been identified,respectively.The residual dose rate around the electrostatic deflector had been obtained by Fluke 451 p ionization chamber.The results of the study show that there is a non-negligible radiological risk to the staff.The experimental setup was composed of ultra-low background liquid scintillation meter and electrolytic concentration device,to measure the activity concentration of tritium in the cooling water.The results show that the activity concentration of tritium in the cooling water of SFC and SSC is slightly higher than that of the background level of accelerator cooling water.According to all the above results,it can be obtained the long-lived radionuclides produced in common materials of accelerator,cooling water,and air aerosols,which contribute significantly to the residual dose rate.Based on empirical formula,calculate the total activity of radionuclides produced in the experimental target,and the residual dose rate of the beam dump at different cooling time.From the comparison results with FLUKA simulation,it’s shown that the FLUKA can be used to analyze the induced radiaoactivity of HIAF high-energy irradiation terminals.Based on the preliminary design parameters given by the accelerator’s physical designers,a preliminary study of the induced radioactivity in HIAF high-energy irradiation terminal was conducted by the FLUKA.The calculations included the activity of main radionuclide produced in beam dumps,cooling water pipes,cooling water,and the air in the terminal.At the same time,analyze the depth profiling of the residual activity produced in the beam dump and cooling water pipes.Analyze the residual dose rate distribution in the terminal at different cooling time,after 100 days continuous operation.The results show that the induced radioactive level of the experimental target and beam dump is slightly higher,and it is necessary to optimize it in the future work.