The pressure relaxation of liquid jets after isochoric heating

During isochoric heating by fast neutron irradiation, a high pressure is almost instantaneously built up inside the falling liquid jets in a HYLIFE (ICF) reactor. It has been suggested that the jets will breakup as a consequence of negative pressure occurring during the relaxation. This is important to both the subsequent condensation process and the chamber wall design. In this paper the mechanism of the relaxation of liquid jets after isochoric heating has been studied with both incompressible and compressible models. The transient pressure field predicted is qualitatively similar for both models and reveals a strongly peaked tension in the wake of a rarefaction wave. The pressure then rises monotonically in radius to zero pressure on the boundary. The incompressible approximation greatly over predicts the peak tension, which increases with time as the rarefaction wave moves toward the center of the jet. Since the tension distribution is as a narrow spike rather than uniform, a cylindrical fracture is the most likely mode of failure. The paper also discusses the available methods for estimating liquid tensile strength

A note on the pressure field within an outward moving free annulus

The outward radial expansion of a free liquid annulus is a common problem of both earlier and current ICF blanket design. Whether the annulus fractures or not depends on the internal pressure and surface stability. In this paper a model based on incompressible cylindrically symmetric flow is used to get a theoretical solution similar to that of the Rayleigh's solution for bubble dynamics. The pressure inside the annulus is found positive all time but the peak is lowering during the expansion. Besides, both surfaces are Taylor stable during such motion. Thus, it is concluded that an annulus in outward radial motion will not cavitate or breakup

The equation of state of liquid Flibe

Flibe (Li{sub 2}BeF{sub 4}) is a candidate material for the liquid blanket in the HYLIFE-2 fusion reactor. The thermodynamic properties of the material are important for the study of thermohydraulic behavior of the concept design, including the compressible analysis of the blanket isochoric heating problem and resulting jet breakup. The equation of state provides the relationship between all the thermodynamic properties. Previously, a soft sphere model of liquid equation of state was used for describing a number of liquid metals. In this paper we have fitted the available experimental data for liquid Flibe with a modified soft sphere model. 5 refs

The analysis of the Flibe jets in HYLIFE-II

In the HYLIFE-2 Inertial Confinement Fusion reactor, an array of Flibe (Li{sub 2}BeFe{sub 4}) jets is designed to protect the chamber from the fusion radiation. During the fusion pulse the Flibe jets sustain an instantaneous neutron and X-ray heating. The high energy neutrons from fusion can penetrate deep into the Flibe jets and the sudden increase in internal energy can induce a great pressure rise inside the jets. The subsequent relaxation of the jets is important for the reactor design, because the configuration of the jets will control the subsequent impact forces of vapor and liquid on the reactor chamber wall. The calculations for the lithium jets in the HYLIFE-1 reactor were done previously by using a compressible flow model with a soft sphere equation of state for lithium. A similar equation of state model for Flibe was recently developed. This model allows us to use the same compressible analysis code to calculate the pressure field in the Flibe jets and to estimate the upper bound of the Flibe tension limit. With these results we can analyze the mechanisms of jet relaxation and breakup. 4 refs., 1 fig