Numerical investigation of passive thermal-hydraulic performance of spent fuel dry-storage system for HTR-PM

Passive thermal performance of a separate buffer storage region of the spent fuel Dry-Storage System (DSS) for High Temperature Reactor-Pebble bed Modules (HTR-PM) is numerically investigated in this study. A 1-D thermal-hydraulic model and the corresponding computer code is developed first to study the natural ventilation characteristics of this region, in which the resistance coefficients are examined utilizing the Computational Fluid Dynamics (CFD) method. Flow distribution to storage wells are first obtained under different operating conditions, and the well with the highest total power and minimal mass flow is determined to be the hot well in the most critical condition. Secondly, with mass flow provided by step one, a 3-D refined model was employed to simulate the conjugate heat transfer coupled with the thermal radiation process inside the hot well, and the temperature profile inside the well was obtained. Finally, the passive thermal performance was evaluated in terms of temperature limits on component materials. It is concluded that this region of dry-storage system is safe under passive conditions in view of material temperature limitation.