Hybrid Analysis of the Simplified Boiling Water Reactor Using RAMONA-4B and CASMO-3 Computer Codes

An analysis of the simplified boiling water reactor (SBWR) is carried out using the reactor analysis computer program RAMONA-4B in an operational transient scenario, a turbine trip with failure of all the bypass valves. The SBWR model represents the vessel's internal components, such as flow areas, diameters, and volumes. The one-quarter-core neutron parameters are calculated with the CASMO-3 transport theory lattice physics computer program. The three-dimensional representation of the reactor core uses some standard fuel design parameters, such as a wide central water rod, 8 x 8 lattice, gadolinium rods, etc. The thermal-hydraulic equations are solved with the RAMONA-4B computer program in a closed loop inside the reactor vessel and in 184 parallel channels (including bypass) in the core.

Finally, the two-phase coolant and neutronic parameters are calculated in steady state and during the turbine trip transient. The results obtained compare favorably with the standard safety analysis report data.