Influence of moderator temperature on fuel channel behaviour under PT-CT contact during LOCA for Indian PHWR

An experimental investigation has been carried out to find the effect of subcooling of moderator temperature under a Pressure Tube (PT) concentric with Calandria Tube (CT) (e = 0) and PT contact with CT (e = 8.5 mm) at a quasi-steady temperature of a center pin at 750 ℃. The circumferential temperature distribution at different axial positions has been established for the PT and CT. The results demonstrated that a large circumferential temperature gradient was observed in the pressure tube during contact conditions. The maximum and minimum temperatures were measured at the top and bottom nodes of the pressure tube. However, the CT exhibited an opposite trend. The maximum temperature difference between the top and bottom surfaces of the PT and CT is 148 °C and 9.1 °C, respectively. However, no substantial temperature variations were observed between the PT and the CT in concentric conditions.