Reactor coolants supercritical fluids

In future generations of nuclear reactors - especially supercritical water reactors (SCWR), 4th generation nuclear reactors and the ITER project (International Thermonuclear Experimental Reactor) - water should still be considered as a suitable coolant fluid, but it will be submitted to more extreme conditions of temperature and LET (high flux of neutrons). All contemporary studies show that it will be beyond reach to extrapolate the existing simulations to these new conditions without experimental determinations of essential parameters such as radiolytic yields and rate constants. 

In this part we will concentrate on heat transfer in SCF reactors. For this, we wiU look at the mechanisms that govern heat transfer from the inside of the reactor (bulk) toward the coolant in the jacket. Many expressions and correlations have been developed for stirred vessels, depending on the vessel geometry, the stirrer type and geometry, and the liquid medium [8-10]. However, none of them have been specifically derived for supercritical fluids. 

At the end of the 20th century and the beginning of the 21st century, helium became quite attractive as a reactor coolant in a gas-cooled fast reactor (GFR) concept and in a very high-temperature reactor (VHTR) concept (for details, see Chapters 3 and 4). Helium within the operating conditions of these reactors is a supercritical fluid (Pioro and Duffey, 2007). 

A modular-type reactor with coolant at supercritical fluid conditions (see Fig. A5.11) was developed at Research and Development Institute of Power Engineering (RDIPE, Moscow, Russia) as an improvement to the existing RBMK (Russian acronym for Pressure Channel Reactor of High Power). 

Carbon dioxide Stable in neutron flux Close to being an inert gas Average thermal conductivity Average specific heat Can be used inside reactor core Reactor coolant in OCRs and AGRs filling gas in CANDU reactors in gap between pressure mbe and calandria mbe working fluid in supercritical CO2 Brayton power cycle... 

Technical Appendices, which provides readers with additional information and data on current nuclear power reactors and NPPs thermophysical properties of reactor coolants, thermophysical properties of fluids at suhcritical and critical/supercritical pressures, heat transfer and pressure drop in forced convection to fluids at supercritical pressures, world experience in nuclear steam reheat, etc. 

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