Research on reconstruction method for pebble-detecting CT system for PB-HTGR - 186633

In the pebble-bed high temperature gas-cooled reactor (PB-HTGR), pebble dynamics in the reactor is important for safe operation. However, the experimental research at present were mostly implemented in two-dimensional models or limited to phenomenological methods. To investigate pebble dynamics using a three-dimensional experimental method, we designed a platform with a pebble-detecting CT system exactly as the proportion of 1:5 with the actual HTR-PM. Multi-slice helical CT can provide cross-sectional images of fuel pebbles at any place during motion, allowing for pebble trajectories to be obtained during the whole unloading process. The purpose of this paper is to design appropriate algorithms to reconstruct cross-sectional images of pebbles for the system. Two methods applicable to distinct situations were discussed and compared. Based on this, a fast reconstruction method was introduced and proved to be the most suitable solution for the system to get pebble trajectories rapidly. The pebble-detecting principle and the effectiveness of the fast reconstruction method were demonstrated by a verification experiment. (authors)