A 3D Code system is developed for burn-up calculation by coupling the MCNP, COUPLE and ORIGEN-S. This work do some benchmark tests with the LWR(PWR and VVER) Pin-cell and Assembly mode. The VVER-100 fuel assembly (fueled with the UO
2 or MOX) with the burnable poison rod Gd benchmark results gave here. The
kinf and isotopic composition of the assembly are good agreement with the others Codes benchmarks. All the results verify the MCCOOR code system.