arXiv subjects

Lluis Batet

Publications and source records attributed to Lluis Batet.

4 recordsLinked to original sources

arXiv2026

Helium Bubbles in Liquid Lead Lithium Solutions: Pressure Inhomogeneities at Interfaces and Non Ideal Mixture Effects

The extremely low solubility of helium in liquid metals may lead to rapid supersaturation, promoting spontaneous formation of helium bubbles by nucleation. Once nucleated, the stability of these bubbles is governed by the properties of the helium liquid metal interface. In particular, interfacial tension between the immiscible phases controls bubble interactions and induces local pressure inhomogeneities. This work is motivated by the need of a better understanding of helium bubble formation in liquid Pb Li alloys, which are of particular relevance for the design of breeding blankets in the future nuclear fusion reactors. We employ classical molecular dynamics simulations to investigate helium segregation in a range of lead lithium systems, including the limiting cases of pure lead and pure lithium. Changes in local pressure are evaluated from direct mechanical calculations, enabling the characterization of interfacial properties. Interfacial tension and radius of the bubble are subsequently determined across multiple thermodynamic conditions, spanning temperatures starting near the melting points of the constituent metals up to 1021 K. The impact of curvature and composition of the alloy on the interfacial behaviour are also investigated.

cond-mat.mtrl-sci↗

arXiv2024

Henry constant of helium in liquid lead-lithium alloys

The solubility of helium in liquid metals is a knowledge of fundamental importance in the design of the future nuclear fusion reactors, since the formation of helium bubbles inside the breeding blankets of the reactors can be a threat to the durability of the devices and, more importantly, to the efficiency of tritium recovery. In the present work we report a detailed set of calculations of the solubility of helium in lead and lead-lithium alloys. A series of molecular dynamics simulations have been combined with a classical perturbative procedure able to compute the free energy of insertion of a helium atom inside a liquid metal bath, directly related to the solubility of helium. As the most important case, the concentration of the eutectic solution has been explored in full detail. We have found that solubility of helium in pure lithium is lower than in pure lead, predicting a value at the eutectic state (16% Li-84% Pb at 508 K) of about $5 \times 10^{-16}$ Pa$^{-1}$. The observed trend indicates that solubilties rise with increasing temperatures.

cond-mat.mtrl-sci↗

arXiv2023

Helium bubbles in liquid lithium: a potential issue for ITER

Future fusion nuclear reactors will produce sustainable energy form the fusion of deuterium and tritium. In order to do so, the reactors will need to produce their own tritium through the neutron bombardment of lithium. Such reaction will produce tritium and helium inside the breeding blanket of the reactor. Helium can trigger nucleation mechanisms due to its very low solubility inside liquid metals. Consequently, the knowledge and understanding of the microscopic processes of helium nucleation is crucial to improve the efficiency, sustainability and safety of the fusion energy production. The formation of helium bubbles inside the liquid metal used as breeding material may be a serious issue that has yet to be fully understood. We provide further insight on the behavior of lithium and helium mixtures at experimentally corresponding operating conditions (800~K and pressures between 1 and 100 bar) using a suitable microscopic model able to describe the helium and lithium atomic interactions, in excellent agreement with available experimental data. The simulations predict the formation of helium bubbles with radii around 10 Angstroem at ambient pressure and with surface tension values between 0.6-1.0 N/m, with a dependency of the concentration of helium. We also report cohesive energies of helium as well as a quantitative estimation of the Hildebrand and Kumar cohesion parameters.

cond-mat.mtrl-sci↗

arXiv2023

Heat transfer correlations for buoyant liquid metal MHD flows in blanket poloidal channels

In recent years, several simulation codes for reproducing liquid metal magnetohydrodynamic (MHD) phenomena have been validated and benchmarked. Accurate simulation codes are crucial to enhance our understanding of how flow behavior affects heat transport in liquid metal-based breeding blankets. Using heat transfer correlations, that model the influence of flow characteristics on the transport of heat, is especially interesting for system designers because it saves them the effort and time in completely simulating every design proposal. Our group has studied the buoyant MHD flow in poloidal channels on the EU Dual Coolant Lead Lithium (DCLL) blanket geometry. Two different codes were used for this study: a 2D fully-developed code and a Q2D-fully-developed code. In this work, we explored the influence of different flow conditions in the heat transport phenomena parametrically. This article presents the results of the calculations performed using the two codes and provides heat transfer correlations for poloidal EU DCLL channels.

physics.flu-dyn↗