News & Analysis
/
Article

New equation of state as international standard to describe thermodynamics of heavy water

DEC 03, 2018
New standard reference equation of state describes the thermodynamic behavior of heavy water to enable greater accuracy and lower uncertainties over a wider range of conditions.
New equation of state as international standard to describe thermodynamics of heavy water internal name

New equation of state as international standard to describe thermodynamics of heavy water lead image

Heavy water is a term used to describe water where the hydrogen nuclei have an additional neutron, increasing the mass density and altering its thermophysical properties. Heavy water is used primarily in applications for certain types of nuclear reactors because it absorbs many fewer neutrons relative to ordinary water. However, the previous standard equation of state describing the properties of heavy water is nearly 40 years old and does not reflect current experimental knowledge or modern equation-of-state techniques.

Herrig et al. from the Ruhr-Universität Bochum (RUB) and the National Institute of Standards and Technology (NIST) have developed a new equation of state for heavy water with greater accuracy, lower uncertainties and a wider range of applicability compared to its predecessor. This new equation of state is being adopted as an international standard and will be implemented in the standard thermophysical property software packages made available through NIST and RUB.

Examples of equations of state, which describe a given substance’s thermodynamic properties, include the well-known ideal gas law and so-called steam tables that engineers use for ordinary water. It is essential to have high confidence in these properties when designing processes that use heavy water, especially for nuclear energy applications. The main difference in the equations of state between ordinary and heavy water is that heavy water has increased hydrogen bonding between the water molecules when in condensed phases, requiring higher temperatures or lower pressures to evaporate or become steam.

The development of this new equation of state ensures high fidelity knowledge of the behavior of heavy water for applications throughout the world.

Source: “A Reference Equation of State for Heavy Water,” by Stefan Herrig, Monika Thol, Allan H. Harvey, and Eric W. Lemmon, Journal of Physical and Chemical Reference Data (2018). The article can be accessed at https://doi.org/10.1063/1.5053993 .

This work was supported by the International Association for the Properties and Water and Steam (IAPWS, www.iapws.org )

Related Topics
More Science
/
Article
Using an iterative approach based on ocean data combined with typhoon trajectory inversion methods significantly improves accuracy over existing methods.
/
Article
Characterizing calcium diffusion during the basic spherification method will optimize the production of beverage pearls.
AAS
/
Article
When a gas cloud collapses to form a star cluster, how many objects form, and what are their masses? Research published today provides answers about the low-mass end of the star and brown dwarf formation process.
AAS
/
Article
A late-night total eclipse of the Moon highlights the coming week, and never mind that this is a minimoon. Sirius holds the meridian at nightfall, just as the Winter Triangle tips to balance on its brightest point.