Study On Reconstruction Algorithm Of Transmission Image In Tomographic Gamma Scanning

Some nuclear waste will be produced inevitably in the production, transportation, storage, and use of the nuclear material. Before the final treatment, the quantity of different nuclides in the waste must be confirmed to check up whether the conditions of the storage are satisfied and to make corresponding plan to treat the waste. Because the density and the distribution of the waste are every uneven in the waste drum, the Non-Destructive-Assay is adaptive to measure the waste. Tomographic Gamma Scanning is one of the advanced Non-Destructive-Assay methods. Tomographic Gamma Scanning can accurately measure the activity of the waste without physical or chemical changes of the waste, and adapts to the waste with middle or high density. Some domestic scholars do some research on Tomographic Gamma Scanning, but have not accomplish the practical application of this technology. Some more researches are needed.The paper focuses on the transmission image reconstruction, one of the pivotal technologies in tomographic gamma scanning (TGS). The TGS technology includes transmission image reconstruction technology and emission image reconstruction technology. Transmission measured is to calculate the gamma-ray's linear attenuation coefficient in order to solve the problem that the gamma-ray attenuation correction is not accurate because of the samples distribution is uneven in gamma-ray spectrometry measurement. Transmission image reconstruction is the emission image reconstruction's premise. It is also the core of TGS measurement technology.The paper use MC method to get the transmission measurement equation, then linearization the equation to get the reconstruction algorithm of transmission image which can be used. The actual wastebin 1:2 size is given by nuclear power station to simulate the experiment in order to validate the researched algorithm, then use the experiment method to validate the researched algorithm again. Result indicated that the researched algorithm is feasible. In view to the gamma-ray's linear attenuation coefficient change with the energy, the paper further research the method that use the multi-energy gamma-ray measurement to replace the single-energy measurement which is traditional method, then use the computer simulation method and experiment method to validate the feasibility of the multi-energy gamma-ray measurement. Result indicated that this method can be used to the practice.