DAYU3D: A modern code for HTGR thermal-hydraulic design and accident analysis
Efficient three-dimensional thermal-hydraulic code facilitates HTGR design
2026-02-11
(Press-News.org)
Advancing Thermal-Hydraulic Analysis for High-Temperature Gas-Cooled Reactors
High temperature gas-cooled reactors (HTGRs) are regarded as a key component of next-generation nuclear energy systems due to their inherent safety characteristics and high outlet temperatures. Accurate thermal-hydraulic analysis plays a central role in both reactor design and safety assessment. However, conventional thermal-hydraulic codes for HTGR typically rely on two-dimensional models and traditional numerical algorithms, which fail to meet the requirements for detailed three-dimensional (3D) analysis and efficient design calculations.
Development of a Three-dimensional Computational Software
Under the leadership of Professor Lei Shi and Professor Ding She, the research team has successfully developed DAYU3D, a three-dimensional thermal–hydraulic design and accident analysis code for HTGRs. Beyond supporting standard 3D thermal-hydraulic calculations, the software enables 3D neutron kinetics simulations and continuous modeling of control rod movements. Furthermore, it incorporates advanced radiation heat transfer calculations along with multi-scale and multi-batch models, significantly enhancing both computational capability and the range of applicability.
Significant Improvements in Computational Efficiency
Based on an in-depth analysis of flow and heat transfer characteristics within HTGRs, the team extensively optimized DAYU3D’s numerical algorithms. They developed an efficient flow-field solving approach alongside a global multi-batch fuel temperature calculation method. Consequently, the code reduces computation time by more than 60% compared with conventional codes, making it particularly suitable for engineering design iterations and large-scale analyses.
Supporting Engineering Design and Safety Analysis
The software has been rigorously tested and validated against over 100 cases. The results showed minimal deviation from reference solutions and experimental data, confirming the reliability of its calculations. Utilizing the code for 3D simulations under both steady-state and accident conditions, the team has preliminarily mapped the 3D temperature distribution patterns of the pebble-bed core and reactor pressure vessel. These findings provide valuable support for the detailed engineering design and safety analysis of HTGRs.
“Developing the DAYU3D code has brought together the team’s extensive experience in HTGR thermal-hydraulic design. DAYU3D also provides an advanced tool for in-depth exploration of thermal-hydraulic behavior and accident phenomena,” said Professor Lei Shi. Professor Ding She noted that, looking ahead, the team plans to further enhance the software’s functionality and models, aiming to achieve fully coupled simulations of HTGR analysis that integrate neutronics, thermal-hydraulics, and chemical corrosion processes.
The complete study is via by DOI: https://doi.org/10.1007/s41365-026-01889-3
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[Press-News.org] DAYU3D: A modern code for HTGR thermal-hydraulic design and accident analysis
Efficient three-dimensional thermal-hydraulic code facilitates HTGR design
