Analyses and sensitivity studies on VVER-1000 using the best-estimate model Relap5/Parcs

Incorporation of fuil three-dimensional (3D) rnodels of the reactor core unto system transient codes allows for a “best-estimate” calculation of interactions between the core behavior and plant dynamics. Recent progress in computer technology has made the development of coupled system thermal-hydraulic (T-H) and neutron kinetics code systems feasible. Considerable efforts have been made in various countries and organizations in this direction. To verify the capability of the coupled codes to analyze complex transients with coupled core-plant interactions and to fully test thermal-hydraulic coupling, appropriate Light Water Reactor (L.WR) transient benchmarks were recently developed on a higher “best-estimate” level. The previous sets of transient benchmark problems addressed separately system transients (designed mainly for thermal-hydraulic (T-H) system codes with point kinetics models) and core transients (designed for T-H core boundary conditions models coupled with three-dimensional (3-D) neutron kinetics models).