Research And Development Of Nuclear Material Level Monitoring System Based On Plastic Scintillator

Nuclear instrument has an important position in the industrial instrument. The research of nuclear detection technology has role to the development of national economy. Nuclear material level meter is a non-contact on-line measurement of material level of the device, which is an important branch of nuclear instrument and can be widely used in petroleum, chemical, pharmaceutical and other industries. The traditional nuclear material level meter with inorganic scintillator exist deficiency, such as low measuring accuracy, limited application scenarios, and so on. Plastic scintillator with its outstanding features gradually be applied to nuclear detection technology,The working principle of nuclear material level meter is studied and the material level monitoring system is designed in this thesis. The basic rule of rays and matter interaction is described, the characteristic of the fluorescence collection in the plastic scintillator is extruded, and HND-S2 plastic scintillator detector performance is validated. According to the principle that the intensity of the rays attenuate after passing through substance and the height of the substance is determined by the change of the rays intensity. The both ends of long plastic scintillator with photomultiplier tube is used in the scintillation detector. Both ends of the plastic scintillator decays exponentially counts are summed. The scintillation detector hardware structure and signal conditioning circuit is analyzed. Furthermore, the hardware architecture and software design is shown in this research.The hardware architecture includes scintillation detector, signal conditioning circuit, MCU module and power supply. The physical model is established, which is based on HND-S2 plastic scintillator. After the nuclear pulse signals are impedance transformed, screened and reshaped by signal adjusting circuit, the signals are passed to the MCU processing and then the processed date communicates with PC. On the software design, system parameter calibration and signal acquisition and processing is introduced, software filtering algorithm is discussed, the way of MCU write and read date from FRAM is described.Relationship between the two ends signal of the detector and the relative position of the point-like radiation sources is established after the performance test results of HND-S2 plastic scintillator. According to the integration operation, the ideal model of the actual field of linear sources is determined, which is used to measure the height of the material level. And it has high measurement accuracy with error of less than 1%.