The coupled kinetic and thermal-hydraulic three dimensional code system NLSANMT/COBRA-IV for PWR core transient analysis

A three dimensional neutron kinetic nodal code NLSANMT has been developed based on the semi-analytical nodal expansion method and nonlinear iteration strategy, and it has been coupled with the subchannel thermal hydraulic core analysis code COBRA-IV to form the integrated code system NLSANMT/COBRA-IV for PWR core transient analysis. This paper describes the features and status of the integrated NLSANMT/COBRA-IV system. A demonstration application of the NLSANMT/COBRA-IV code to rod ejection accident analysis is presented using the OECD NEACRP PWR hot zero power full core rod ejection benchmark problem. The NLSANMT/COBRA-IV solution agrees well with the reference solution, even when one node per assembly and one channel per assembly are used.