Effect of sub-cooling on fuel channel behaviour during LOCA for Indian PHWR

During LOCA with ECCS failure, the removal of decay heat from the channel to a moderator plays a significant role in determining the fuel bundle temperatures. An experimental investigation has been carried out to study the effect of change in moderator temperature (65 degrees C, 75 degrees C, and 85 degrees C) on the fuel channel at a steady state of 900 degrees C center pin temperature. The results show that at different moderator temperatures, there is insignificant variation in the temperature of PT, whereas for CT appreciable temperature gradient has been observed. The maximum heat transfer coefficient for CT was attained at 65 degrees C moderator temperature. Even with an increase in moderator temperature, channel integrity is maintained, and the moderator acts as an ultimate heat sink for all three moderator temperatures.