The Key Technology For Rapid Measurement Of The Water Radiation

Radioactive materials are playing more and more important role in energy, medicine and industry, however, the leakage of which will cause considerable harm to human. Because of the particularity of nuclear facilities construction, the pollution of surrounding water bodies can be very severe. How to monitor environmental radioactive pollution in water body quickly and efficiently, especially in the condition of nuclear and radiation accidents, such as Japan’s fukushima nuclear accident, will need an equipment which can rapid detection of contamination of environmental water. Measurement of alpha and beta nuclides in water is a fast and feasible method in the determination of the water pollution.Recently, the existing radioactive particle detection equipment for alpha and beta nuclides, usually, there will be complex re-processing to samples prior to test, such as Sintering or enriching several liters of water. This process is very time consuming, which reduces the detection efficiency of the method in emergency situation greatly. As a result, the detection equipment cannot the play an effective role when the disasters and special come. In addition, the existing testing equipment are generally lack of mobility and is not applicable in emergency situations. Therefore, the research in the key technology of the rapid measurement device for water contamination is of large significance.The decay of radiation particles is a random process, according to statistical theory, we can use an average to describe this kind behavior. So we need to study and record the total number of alpha, beta decay in a particular case, then, the average number of decay per unit time can be determined according to statistical theory. Traditional detection for water radionuclide is usually based on water samples measured after complicated and tedious enrichment, which is not conducive to the fast detection of radioactivity level in water at the scene test. Based on full literature research home and abroad, this project intends to design an alpha and beta measurement system based on the LSC (liquid scintillation counting), to validate the key technology of fast measuring radioactive degree in water.The key technologies excepted to solve include:structure design of testing device, the choose of ferment scintillator, the selection of photomultiplier tubes type, the front-end electronics circuit, data acquisition and storage system control analysis software. For Test system structure that is used to verify the key technical indicators of test equipment, the design of which need to satisfy the requirement of the system test. There are a variety of scintillator for radioactive measurement that can be chosen, according to the requirements of fast measuring radioactive water about this project. It is appropriate and necessary as well to choose the scintillator with low background and high efficiency. As for Photomultiplier tube, which requires a high sensitivity, low dark current and highly efficient light-induction ability, when coupled with appropriate optical, it can improve the efficiency of light detection effectively. The design for front-end electronics circuit should meet the requirements the front-end electronics circuit of just this project and fit the back data acquisition circuit boards very well. The function of data acquisition and storage system:electronically method is to remove scattering background noise caused by the sample vials and glass of photomultiplier tubes and so on. So that, it is necessary to select a kind of high-speed ADC to perform analog-digital conversion to effective signal, and then screening alpha and beta particles according to the characteristics of signal, and realize of total number for alpha and beta decay in the end through the combination of software and hardware. Lastly, control analysis software is for the parameter setting, system control, and the implementation of screening and activity discrimination for alpha and beta particles.