Verification of the Hexagonal Ray Tracing Module and the CMFD Acceleration in nTRACER

nTRACER is a direct whole core transport calculation code for 3D core analysis, which employs a planar Method Of Characteristics (MOC) calculation and Simplified P₃(SP₃) axial calculation accelerated by 3D Coarse Mesh Finite Difference (CMFD) method. So far, modular ray and CMFD formulation of nTRACER are applicable in rectangular geometries, since the code was designed for general PWR cores analysis. However, fast reactor cores are mostly based on the hexagonal geometry to achieve high power density and in order to simulate these fast reactors, nTRACER needs to equip a calculation capability to deal with hexagonal geometries. The objective of the work is to implement and verify the hexagonal ray tracing module and the CMFD acceleration in nTRACER. For 3D C5G7 hexagonal variation benchmark, nTRACER solution matched well with McCARD with the maximum 6 pcm error in the reactivity and the maximum RMS 0.52% error in the 2D integrated pin power distribution. The maximum absolute power error was 0.37% in radially integrated axial pin power. Since verifications in this work were based on the C5G7 benchmark cross-section, it is necessary to perform with 47 group condensed cross-section in nTRACER comparing with continuous McCARD solution.