Reconstruction methods of Axial and Radial Leakage for 2D/1D fusion method

The 3D whole-core heterogonous transport calculation plays a very important role in high fidelity calculations for reactor physics, among which, 2D/1D fusion method (including 2D/1D method) is one of the most promising methods. In conventional 2D/1D fusion method, the axial leakage is flat on the top/bottom surfaces of the homogenous cells and the radial leakage is flat along the axial direction of the 2D calculation plane, so these approximations will get some accuracy lost. This work is to analysis and minus the errors these approximations bring. In 1D calculation the radial leakage is fitted along axial direction while in 2D calculation the distribution of axial leakage is also introduced. The numerical results indicate that these two improvements reduce the errors brought by the flat leakage approximation.