Abstract
Carbon/graphite bricks are used as the supporting structure and neutron moderator for high-temperature gas-cooled reactors (HTGR) because of their excellent mechanical properties and neutron moderation ability. These bricks require computed tomography (CT) non-destructive detection before they are put into service. The number and size of defects inside them must be below the limits to ensure the reactor’s operation. However, the CT non-destructive detection system cannot find part of the defects due to the image artifacts caused by scattered photons. This study thus proposes a Monte Carlo scatter correction method, which uses simulation software based on photon transportation to simulate the physical process of CT scanning. CT image quality can be improved by calculating and deducting the share of scattered photons in the data received by the detector. Results prove that the Monte Carlo scatter correction method is effective. The influence of the ray source energy on the scatter correction is also discussed to assist the design of the detection system. We believe our research would help to improve the defects inspection performance of the detection system and is of great significance to ensure the safety of the reactors.
