Ideal tensile strength of select coolant materials for generation-IV nuclear reactors

Generation-IV nuclear reactors employ sodium, lead and bismuth(Na, Pb and bismuth) as coolant materials. This technological application requires the knowledge of these metals’ properties over a broad temperature span and pressure. Ideal tensile strength is an important characteristic parameter of substances in the metastable state. It can be determined using an appropriate equation of state. Being a characteristic property, the ideal tensile strength is substance-dependent. Hence, Na, Pb and Bi will have different values of the ideal tensile strength. However, the original van der Waals equation of state(vdWEoS), for all substances including Na, Pb and Bi gives the same value of 27 times the critical pressure for the ideal tensile strength. This is physically not reasonable. This points out the need for the generalization the vdWEoS to yield physically reasonable values of the thermodynamic properties of Na, Pb and Bi. To improve its predictive capability, the vdWEoS is generalized into a three-parameter and a four-parameter equations of states with modified attractive terms. The substance-specific parameters of the generalized van der Waals equation of state(gvdWEoS)for Na, Pb and Bi are determined through their vapour-liquid critical-point parameters. The gvdWEoS are employed for determining the ideal tensile strength of Na, Pb and Bi. These values of are found to be-2.6146GPa,-5.7299GPa and-4.3888GPa, respectively. That is, Na, Pb and Bi in the condensed state can withstand, without rupturing, a stretching tension of 2.6146GPa, 5.7299GPa and 4.3888GPa, respectively.