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[Display omitted] • Combining global simplified and local turbulence models to calculate flow details. • Analysis of the low-pressure heater pipe failure causes. • Simulate the low-pressure heater with the porous medium model. • Obtained flow information in the damaged local area. Low-pressure heaters are critical heat exchange equipment in thermal and nuclear power generation. The high-speed steam flow in the low-pressure heaters induces pipe vibration, causing pipe failure. The large size and complex flow make it hard to calculate directly. This paper employs a combined method of the porous medium and local models by substituting the boundary to calculate and prove steam flow trajectory and velocity are consistent with the actual situation. The analysis of the turbulent kinetic energy exhibits that the primary causes of pipe vibration are the periodic vortex shedding and the impact of the impingement plate on the pipes. The stress analysis indicates that the loosening of the pipes leads to a 368 times amplification of the shear stress by 0.1 MPa. The most crucial step in solving such a problem is to strengthen the fixation of the pipes, especially near the shell region. [ABSTRACT FROM AUTHOR]

• A 3-D detailed porous medium model for wire wrapped fuel bundles has been proposed. • The prediction results of the model proposed agree well with experimental results. • The model has been validated under various conditions. • The model could simulate wire-wrapped fuel bundles with low computing cost. Wire-wrapped fuel bundles have been widely used in SFRs, and the conjugate heat transfer between wire-wrapped fuel bundles plays a key role in safety characteristics of SFRs. However, due to the existence of helical wire spacers, the geometry of fuel bundle becomes quite complicated, bringing challenges to realistic CFD modeling. A porous medium model for simulating conjugate heat transfer between fuel bundles have been proposed in this study. The geometries of fuel rods and wrapper tubes are preserved and helical wire spacers are treated as solid body of porous medium in this model. The flow resistance induced by helical wire spacers is considered by adding additional flow resistance source terms to momentum equation and the transverse mixing effects caused by wire spacers and thermal plumes are accounted by modifying diffusion terms in energy equation of porous medium model. The sodium experiment of 19-pin wire-wrapped fuel bundle under forced convection performed by ORNL and sodium experiments of multi-bundle systems named CCTL-CFR and PLANDTL-DHX under mixed convection conducted by JNC were selected as benchmark. Comparison results show that under both forced and mixed convection, this model could attain considerable accuracy in the prediction of conjugate heat transfer between fuel bundles with relatively low computational cost and have the potential to simulate core-wide temperature distribution of SFR. [ABSTRACT FROM AUTHOR]