Understanding the influence of eccentric pressure tube on the thermal behavior of 37-element based PHWR channel under accident condition

•Experiments were carried out in a non-oxidizing environment by varying the eccentricity of PT.•With the exception of the center pin simulator, a noticeable temperature gradient was established for an eccentric PT in the CT, PT, and bundle simulators.•The rate of heat dissipation from the bottom pin simulator was significantly higher than that from the top simulator for an eccentric PT.•For a PT eccentricity of 4 mm and 8 mm, the temperature at the bottom circumference of PT was lower than the upper circumference.•The lower circumference of the CT is at a higher temperature than the top circumference in the case of the eccentric PT. During a Loss-of-Coolant Accident (LOCA) combined with Loss-of-Emergency Core Coolant (LOECC), the convective cooling in the channel is degraded, resulting in a rise in bundle temperature due to heat decay despite the reactor being forced to shut down. The fuel bundle radiates heat to the Pressure Tube (PT), causing its thermomechanical properties to deteriorate at certain high temperatures and, depending on the channel pressure; PT may either sag or balloon. The assessment of the influence of eccentric PT on temperature distribution in the channel is critical for reactor safety. In the current study, various sets of experiments were carried out in a non-oxidizing environment by varying the eccentricity of PT, and for each of the experiments, the Joule heating of the bundle simulator was performed. A temperature profile was obtained for the bundle simulator, PT and Calandria Tube (CT). The results showed that in the channel, with the exception of the concentric arrangement, there was substantial temperature variation for all PT arrangements.