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Proceedings of the 24th National and 2nd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2017)

ISBN En Línea: 978-1-56700-478-6


DOI: 10.1615/IHMTC-2017.880
pages 629-634

P. K. Verma
Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

Arun Kumar Nayak
Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, Maharashtra, India; Reactor Engineering Division, Bhabha Atomic Research Centre, Mumbai-400085, India


In a nuclear power plant continuous cooling is required for the removal of heat generated in the reactor core. Even during shut down condition decay heat is being continuously generated. A continuous core cooling system maintains flow of coolant to prevent any core damage due to overheating. This cooling system utilizes large amount of water pool as a heat sink, an immersed heat exchanger and associated piping to transport heat from core to heat sink. The role of efficient core cooling system is very important in this context and passive systems are the better in view of reliability. New and advanced nuclear reactors like ESBWR, AP 1000 and AHWR1 utilize similar arrangements having large amount of water pool as a heat sink for this purpose. However, heat transfer by natural convection in water pool poses a problem of thermal stratification. Due to thermal stratification hot layers of water accumulate over the relatively colder one. The heat transfer performance of heat exchanger gets deteriorated due to hot plume which surrounds the immersed heat exchangers(IC's in AHWR). Innovative technique is developed for suppressing thermal stratification in such type of pools with submerged heat exchangers. The concept involves employing multiple shrouds which envelops the isolation condensers and forms a closed path for natural circulation in the large pools. The concept has been experimentally demonstrated in the scaled water tank. Relap5 study has been performed previously to study the effect of shroud to eliminate thermal stratification and it is found that the shroud arrangement is adequate to eliminate the problem. To validate the simulated results a scaled facility is designed and fabricated and the results of the experiments are discussed in this paper.