An improvement of Compton scatter imaging with wide aperture detectors a Monte Carlo study

摘要

A novel NDT (nondestructive testing) imaging technique which is based on the measurement of Compton-scattered photons and uses wide-aperture detectors has been developed. With this technique, the inspection speed can be improved because the scanning activities can be reduced by one degree of freedom. Using wide-aperture detectors serves to simplify the design of measurement systems, and the data collection time at each step in the scanning process can be reduced due to the removal of the usual efficiency-reducing focusing collimator. To study the imaging process of the novel NDT system, a number of Monte Carlo calculations have been performed. The Monte Carlo code has been validated by comparison to the widely accepted general-purpose MCNP (Monte Carlo neutron-photon) code and has been found to run over ten times faster than the MCNP code for this particular research. As a result, the NDT system has been designed to deal, in particular, with the pipe wall thinning problems widely observed in nuclear power plants and some fossil power plants. In this application, the contour of a pipe inner surface can be reconstructed in a very straightforward manner, and the scanning activities can be reduced from three dimensions to two dimensions.