Time-dependent neutron transport method based on three-dimensional method of characteristics

The 3D Method of Characteristics (MOC) has high numerical accuracy, geometrical flexibility, making it suitable for the simulation of advanced reactors with complex geometry, while the development of transient solvers based on it is still relatively limited. In this work, transient method was developed based on 3D MOC solvers of OpenMOC and predictor-corrector quasi -static method and the C5G7-TD benchmark problems were used to verify the implementation. In 2D cases and 3D moderator density change cases, the results of OpenMOC were in good agreement with the results of other transient codes. In 3D control rods movement cases, there are oscillation errors between the existing results of different transient codes due to the control rod cusping effect. This work is based on the refined axial modeling of 3D MOC, which avoids the cusping effect and provides new results of C5G7-TD benchmark.