Analysis of the PHWR benchmark transient using a high-order spherical harmonics-nodal collocation method and treatment of rod cusping effect

We develop and validate node homogenization methods, based on one and three-dimensional node equivalent problems, that improve the volume weighted method for the treatment of the rod cusping effect. The numerical implementation of these techniques in a numerical approach based on general spherical harmonics, nodal collocation method, for arbitrary odd order L, and fully implicit time discretization, is verified on the AECL-7236 PHWR benchmark transient, showing the validity and convergence of the P-1 and P-3 approximations and the ability of the method to give accurate results for the relative power and scalar flux when a coarse spatial mesh combined with advanced homogenization techniques is used.

Automated summary

This study developed and validated node homogenization methods based on one and three-dimensional node equivalent problems to improve the treatment of rod cusping effect in volume weighted method. The numerical implementation of these techniques in a numerical approach based on general spherical harmonics showed the validity and convergence of P-1 and P-3 approximations in AECL-7236 PHWR benchmark transient, indicating the method's ability to provide accurate results for relative power and scalar flux with coarse spatial mesh combined with advanced homogenization techniques.