The physical phenomena of rewetting and quenching are of prime importance in nuclear reactor safety in the event of Loss of Coolant Accident (LOCA). In such a case, the fuel pins become dry hot. Under this condition, cold water is injected from emergency core cooling system (ECCS). The quenching behavior of such heated rod bundle (re-flood heat transfer behavior) is quite complex. It is well known that Nanofluids have better heat removal capability and a high heat transfer coefficient owing to their enhanced thermal properties. Recent investigations have shown that the addition of the Al2O3 nanoparticles result in better cooling capabilities as compared to the traditionally used quenching media. In this context, the authors have carried out experiments on quenching behavior of hot zircalloy tube with water and nanofluids as stated above. Quenching of the tube was observed to occur within few seconds in both the cases in the presence of decay heat. It was also observed that the nanofluids showed slightly reduced quenching time as compared to water.