Research on Thermal-hydraulic Calculation Method of Steam Generator for Integrated Fast Reactor

Integrated fast reactors emerge as the future direction for sodium cooled fast reactor systems. Steam generator is critical components in reactor systems. Their design directly impacts integrated fast reactor construction quality. Developing specialized thermal-hydraulic analysis codes becomes an urgent priority. To develop the codes, physical and thermal-hydraulic models was firstly selected. Water side was divided into four regions: subcooled region, nucleate boiling region, film boiling region, and superheated vapor region. The Dittus-Boelter correlation was applied for Nu calculation in the subcooled region. Chen’s correlation was applied to calculate two-phase heat transfer coefficients in the nucleate boiling region. The Groeneveld’s correlation was applied for Nu calculation in the film boiling region. And the Sieder-Tate correlation was applied for Nu calculation in superheated vapor region. Single-phase pressure drop was calculated using the Colebrook-White formula, and two-phase friction pressure drop was calculated using the two-phase friction pressure drop multiplier factor for homogeneous flow. Then the framework was established through meticulous grid generation on the steam generator model, employing moving mesh methodology for steady-state simulations and fixed mesh approach for transient condition analysis. Next the homogeneous flow equation and three conservation equations were discretized. Gill’s algorithm was used to solve the thermal parameters. The calculation results of the code were verified by using the design values of the steam generator of China Experimental Fast Reactor (CEFR). The developed thermal-hydraulic analysis code demonstrates exceptional performance in SG-33 steam generator design calculations, with results matching design parameters within required accuracy thresholds. The relative error of the tube length is always kept below 15%. Transient flow step-change validation tests reveal the code’s dynamic capabilities, requiring 9 120 seconds to simulate 380 second transients, resulting in a 24∶1 computation-to-physical-time ratio. The system exhibits clear transient behavior, with flow rate step changes triggering immediate temperature responses in both primary and secondary sides. The validation process confirms the code’s precision in tracking dynamic temperature fluctuations and its capability for transient simulation. Verification results demonstrate compliance with accuracy requirements, meeting large steam generator thermal-hydraulic analysis demands. On this basis, the steady-state and transient thermal-hydraulic characteristics of large steam generators were calculated, which lays a foundation for the design of integrated fast reactor large steam generators.