Monte Carlo Design Of Low Concentration Tritium Water Detector Based On CaF₂（Eu）

The development of nuclear energy is always accompanied by the generation of radioactive waste.Tritium is one of the most common radionuclides found in nuclear waste that is dumped into the environment.The concentration of tritium needs to be monitored for radiation protection and tritium safety.It is difficult to monitor the concentration of tritium in water because of the low energy of the beta ray produced by tritium decay,which has a range of only a few microns in water.In order to solve the problem of high cost of continuous tritium water concentration monitoring with traditional liquid scintillation detection method and avoid the generation of extra organic radioactive waste in the detection process,a tritium water detection system based on solid scintillation CaF2(Eu)was designed in this paper.CaF2(Eu)is a kind of scintillation material sensitive to β radiation.Due to its insoluble properties and excellent luminescence,CaF2(Eu)is often used to detect β particles in water.By using Geant4 for Monte Carlo simulation,the geometry of the detector is optimized and two on-line tritium water detection systems based on CaF2(Eu)solid scintillators are designed.The detection system based on CaF2(Eu)scintillator sheets has higher detection efficiency,while the detection system based on CaF2(Eu)with internal pipe has better tritium flow connectivity.The main components of the scintillation detection system based on CaF2(Eu)include scintillation sheets,sample chamber,reflective aluminum foil,photomultiplier tube,optical window and coincidence detection system.For the tritium water detection system based on thin scintillator sheets,the design of multiple sample chambers can improve the counting rate of the detection system and lower the detection limit.The detection limit of the tritium water detection system can reach 7.46Bq/mL at the count time of 10min,which can meet the detection requirements of low concentration tritium water at the concentration of 10Bq/mL.The CaF2(Eu)solid scintillation counter with a pipe allows tritium water to circulate in it,thus greatly improving the feasibility of on-line tritium measurement in solid scintillation system.The system’s detection performance can be improved further by increasing the length or number of detecting units.,so as to achieve the goal of on-line measurement of low concentration flowing tritium water.