Enhancement of COBRA-EN capability for VVER reactors calculations

Thermal–hydraulic subchannel treatment of a typical hexagonal fuel assembly of VVER nuclear reactor core in steady-state or transient conditions needs consideration of detail geometry of fuel rods and subchannels. The COBRA-EN code could not generate the hexagonal subchannel and fuel-subchannel connections automatically and user must enter all required data for neighbor of each subchannel manually. Furthermore, treatment of the flow and heat transfer equations in the code needs to consider exact linear fission heat flux throughout the core and then one require assigning the heat flux manually for every discretized cell in the domain of problem. Therefore, user must prepare exact geometry of hexagonal fuel assembly which is time consuming. To improve the code capability and above adversity, the automatic hexagonal subchannel generation and power distribution schemes are developed and implemented within COBRA-EN source subroutines.

► The COBRA-EN code developed for automatic hexagonal subchannel analysis.
► Linear heat power mapping is implemented automatically.
► The time for preparing input file is reduced.
► It is easy coupling of developed COBRA-EN with neutronic codes.