A new concept to suppress the thermal stratification in GDWP of AHWR

Advanced and innovative reactor systems are considering the use of large pools as heat sink for various safety functions like decay heat removal or containment cooling. These designs generally have heat exchangers immersed in the pool or alternatively, pool water passing through the heat exchangers. For enhanced safety and reliability, preferred heat transfer mode is considered to be passive i.e. natural convention so that heat sink availability is maintained even in absence of failure of power supply and active components. However, heat transfer by natural convection to large pools poses a problem to the designer i.e. thermal stratification. As a result of natural convection, hot layers of water may accumulate over the relatively cold one and in turn inhibit the natural convection itself. Not only the heat transfer performance may get deteriorated but some parts of the pool like concrete wall may be subjected to high temperature which is not desirable. Employing shrouds around the heat source in the pools is one of the simplest ways of suppressing the thermal stratification. This paper discusses the assessment of a few schemes of shrouds conceived to suppress the thermal stratification in large pools with immersed heat exchangers and promote the mixing across the pool by natural circulation. (author)