The Equation of State of Water at High Temperatures and Pressures, a Preliminary to Damage Calculations

Third and last of a series documenting the thermodynamic relations of water at high temperatures and pressures, such as might be caused by a nuclear burst. This report evaluates the Becker-Kistiakowsky-Wilson equation — also known as the Halford-Kistiakowsky-Wilson or HKW equation; tests modifications proposed by various Los Alamos researchers; and proposes some new modifications. In the thermochemical region, calculations are primarily a matter of interpolation between areas of known results and accepted physical theory to obtain equations of state for the large missing area. The authors therefore redesign the state equations so as to achieve a smooth joining of the Thomas-Fermi model results at 20 megabars with experimental data on the Hugoniot curve under 1 megabar. This required treating some BKW constants as functions of thermodynamic coordinates, and calculating pressure/specific volume/ internal energy relations for the region above about 300 kilobars. (See also RM-4969, RM-5050.)