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The safety related mini-pleat HEPA Filter is an important part of nuclear power plant air cleaning system. It is used for eliminating radioactive particles generated during the operation of nuclear power plant. The rated flow of mini-pleat HEPA filters is much larger than that of other types HEPA filters, therefore the amount of solid radwaste can be reduced more effectively. Relevant domestic and foreign standards are studied and performance requirements are analyzed in this paper. And finally safety related mini-pleat HEPA Filters are designed and verified based on performance requirement tests.

An automatic measurement system based on the stationary wavelet transform (SWT) of vibration signal is developed to obtain the depth and width of gas guide grooves in the gun barrel. The system consists of the programmable logic controller module used to control the motions of system components, a mechanical apparatus used to fix the gun barrel and position the transducer, and a measurement device used to capture and analyze the measured data. With the SWT, the interference noise, baseline wander, and interference harmonics are successively eliminated from the captured displacement signal. Afterwards, the peak and valley points are detected out, which, respectively, represent the information of groove depth and of groove width. Finally, the dimensions of the gas guide groove are determined according to the points detected out and the calibration information. In the experiment, the steps of data processing are provided in detail, and the analysis results show that the measuring error is less than 3 %, which can meet the actual requirements.