Optimized design of on-line burn-up measuring system for high temperature gas cooled reactor

To solve the problem of the upper limit of the radioactivity measuring requirements for the HTGR on-line burn-up measure system, the structure of the device can be further optimized. Aim to optimized system, this thesis uses MCNP to simulate shield, collimator and multi-sphere impact on the detection upper limit. Making a synthesis of simulation and actual measured results an optimizing structure is design. The result shows: this plan can enhance the shield efficiency and meet the upper limit counts for the HPGe detector. (authors)