Comparison of thermophysical properties (NIST REFPROP Ver. 10) and heat transfer to heavy and light water at subcritical pressures

Currently, 48 Pressurized Heavy Water Reactors (PHWRs) are in operation worldwide, and about 8 PHWRs are planned to be built. There are some developments to design Small Modular Reactors (SMRs) with heavy water, and, moreover, to develop high-thermal-efficiency Nuclear Power Plants (NPPs) equipped with SuperCritical Water-cooled Reactors (SCWRs) (Generation-IV concept), which are based on current achievements in PHWR technologies. In support of operation of current PHWRs and Generation III+, and to develop SMRs and SCWRs with heavy water, a reliable source of thermophysical properties of heavy water is required. For a number of years, the National Institute of Standards and Technology (NIST) REFerence PROPerties (REFPROP) software Version 9.1 was used for this purpose. (However, in industry properties dated to 1980s-1990s are still in use.) This year, NIST has announced releasing a new version of REPROP Ver. 10.0 in which "New reference equations of state for ... heavy water" are introduced. Therefore, it is important for testing, design, and safe operation of PHWRs to verify how the new NIST REFPROP version differs from the previous one in terms of various thermophysical properties, and, in general, how heavy-water properties differ from those of light-water, which usually is used as a modelling fluid instead of heavy water in thermalhydraulics experiments. (author)