Development of three dimensional transient analysis code STTA for SCWR core

• A coupled three dimensional neutronics/thermal-hydraulics code STTA is developed for SCWR core transient analysis.
• The Dynamic Link Libraries method is adopted for coupling computation for SCWR multi-flow core transient analysis.
• The NEACRP-L-335 PWR benchmark problems are studied to verify STTA.
• The SCWR rod ejection problems are studied to verify STTA.
• STTA meets what is expected from a code for SCWR core 3-D transient preliminary analysis.

A coupled three dimensional neutronics/thermal-hydraulics code STTA (SCWR Three dimensional Transient Analysis code) is developed for SCWR core transient analysis. Nodal Green’s Function Method based on the second boundary condition (NGFMN_K) is used for solving transient neutron diffusion equation. The SCWR sub-channel code ATHAS is integrated into NGFMN_K through the serial integration coupling approach. The NEACRP-L-335 PWR benchmark problem and SCWR rod ejection problems are studied to verify STTA. Numerical results show that the PWR solution of STTA agrees well with reference solutions and the SCWR solution is reasonable. The coupled code can be well applied to the core transients and accidents analysis with 3-D core model during both subcritical pressure and supercritical pressure operation.