Research on high-fidelity neutronics-thermal-mechanical coupled transient analysis methods for heat pipe microreactors

Key Points

• To develop high-fidelity coupled analysis methods for transient analysis in heat pipe microreactors.
• Implemented VITAS for neutron dynamics and FEniCS for thermal conduction and thermomechanics.
• Introduced a steam cavity-porous core model for temperature distribution analysis.
• Utilized Picard iteration for power, temperature, and density information exchange.
• The method reduced effective multiplication factor calculation error to within 200 pcm compared to 1000 pcm when expansion was neglected.
• Power response showed rapid initial changes followed by gradual adjustments due to thermal feedback; power ratio ranged from 0.24 to 4.9 at 51 seconds.
• Failure of two peripheral heat pipes caused localized temperature increases and enhanced stress concentration.