Grant: Strategic Projects - Group

The ""Generation IV"" CANDU Supercritical Water-Cooled reactor (""SCWR"") is a conceptual design for a would produce super-critical water at temperatures as high as 625?°C to generate electricity, hydrogen and district heating. The use of super-critical water to carry heat from the reactor core to the turbine will generate much more extreme water chemistry conditions than those found in the current CANDU-PHW design, which operates from 250 to 320?°C. The long term viability of the Gen IV CANDU-SCWR concept depends on the ability of designers to predict and control water chemistry, in order to minimize radionuclide transport and subtle corrosion effects. The region of most importance is the range from 275 to 450 ?°C and 25 MPa, the so-called ""pseudo transition zone"" which includes sub-critical and supercritical aqueous solutions at liquid-like densities. This is a frontier region of hydrothermal chemistry, both because the SCWR would require a unique water chemistry, not previously seen in the primary coolant circuits of pressure-tube reactors, and because most quantitative studies of aqueous solutes do not extend above 300 ?°C. This proposal seeks funding for a collaborative project that will use state-of-the-art instruments to determine ionization and association constants for simple acids, bases, dissolved metals, and organic complexes under near-critical and super-critical conditions that will be encountered in the SCWR. The instrumental methods include Raman and UV-visible spectroscopy, calorimetry, visualization, and modelling techniques. These are extremely specialized pieces of high-precision equipment, with capabilities shared by few other laboratories in North America. The project includes the construction of high-pressure cells and calibration of the equipment for operation in the supercritical region, measurements on several acids, bases and salts relevant to Gen IV steam generator chemistry, and the development of equations to predict the behaviour of aqueous species under these extreme conditions.