A Next Generation Method for Light Water Reactor core analysis by using Global/Local Iteration Method with SP3

The Global/Local Iteration Method (GLIM) capability was implemented into the in-house developed nodal code, NuCoT, which was based on the Hybrid Nodal Green's Function Method (HNGFM) with the diffusion/SP3 approximations. A procedure was proposed for obtaining the Even Parity Discontinuity Factor (EPDF) in SP3 method. The accuracy of NuCoT with GLIM was verified by using two benchmark problems, KAIST and C5G7, with reference solutions calculated by NEWT and MCNP respectively. The results of NuCoT show that the accuracy of the GLIM is comparable to the whole core pin-wise calculation. The SP3 calculation with EPDF is better than the diffusion result. For the KAIST problem using GLIM, the Root-Mean-Square (RMS) of pin power error is ∼1%, the maximum pin power error is ∼6%, and the keff error is <83 pcm for All-Rod-In case and <135 pcm for All-Rod-Out case. For the C5G7 problem, the RMS of pin power is <0.8% and the maximum error is <4%. The keff error is <80 pcm in 2D problem and <200 pcm in 3D rodded problem.