Applying conformal mapping method to Hybrid Nodal Green's Function Method for two-dimensional simplified HTTR core calculation

The method was further verified by performing a 2D simplified HTTR problem and compared with MCNP result. The statistical errors of keff was <10 pcm and of fission power was <0.1%. The results of Hex-capability of NuCoT showed that using supercell method for cross section generation for homogenization of fuel block gave more accurate results than using single fuel block with periodic boundary condition. For the control rod block that contains three large void channels, using anisotropic diffusion coefficient resulted in more accurate keff. In the all-rods-out condition and the partially-controlled condition, the difference in keff was <140 pcm and in maximum power was <0.8%. In the all-rods-in condition, the error in keff and maximum power error were 413 pcm and 1.1%, respectively.