Heat transfer at supercritical pressures

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Water-cooled nuclear reactors operating at subcritical pressures (10 - 16 MPa) started to be developed at the end of 1940s and have been used for the last fifty years.  At the same time, i.e., as early as the 1950s, concepts of SuperCritical Water-cooled nuclear Reactors (SCWRs) were studied in the USA and Russia.  Currently, several countries (Canada, European Union, Japan, Korea, Russia, and USA) have started to work in that direction, building on the successful international deployment of supercritical and ultra-supercritical boilers and turbines for coal-fired power plants.  The main objectives of using supercritical water in nuclear reactors are:1) Using the increased temperatures and a direct-cycle turbine to increase the thermal efficiency of modern nuclear power plants (NPPs) from 33% to 40 - 45% for electricity production, or more than 50% with co-generation, and2) Using a more compact design that results in decreased capital and operational costs and hence in decreased capital and electrical energy costs (~$1000 US/kW).Therefore, the proposed work in support of SCWR activities will consist of the following parts:1) Creation of a reliable supercritical heat-transfer database for the primary SCWR coolant such as light water and for two modelling fluids such as carbon dioxide and R-134a;2) Developing heat-transfer correlations for supercritical water, carbon dioxide and R-134a, which can be applicable within a wide range of flow conditions and identify conditions for the deteriorated heat transfer;3) Conducting analysis to find modelling parameters for scaling from supercritical water to modelling fluids and vice versa;4) Designing and building a small-scale natural-circulation heat-transfer loop for experiments in supercritical water and modelling fluids at the University of Ontario Institute of Technology.5) Participating in supercritical forced-convection heat-transfer experiments in water and modelling fluids flowing in tubes and bundle geometries at Chalk River Laboratories and using data from Russian test facilities.6) Keeping a leading role in the world in developing the SCWR concept through innovative research and world-class publications and presentations; and7) Creating an educational basis and training of Highly Qualified Personnel (HQP) in the area of nuclear engineering and thermalhydraulics, whom are desperately needed in industry.    Long-term objective is a creation of the supercritical-water heat-transfer database for fuel bundles and reliable correlations for calculating heat transfer coefficient at these conditions and limits for the deteriorated heat transfer.  Also, these correlations have to address thermalhydraulics safety issues.