CFD analysis and optimization of a liquid lead–bismuth loop target for ISOL facilities

D Houngbo,L Popescu,P Schuurmans,M Delonca,R Losito,C Maglioni,T Stora,P Bricault,J Vierendeels

doi:10.1016/j.nima.2014.12.056

Abstract

In the context of the forthcoming next generation of Radioactive Ion Beams (RIBs) facilities based on an Isotope Separation On Line (ISOL) method, the development of production targets capable of dissipating the high power deposited by the primary beam is a major challenge. The concept of a high-power target based on a liquid Pb–Bi loop incorporating a heat-exchanger and a diffusion chamber was proposed within EURISOL DS and is being developed within the LIEBE11LIquid lEad Bismuth eutectic loop target for EURISOL (LIEBE). project. Due to the non-static character of the target, specific hydrodynamics issues are of concern. In this paper, these issues are studied mostly based on three-dimensional (3D) Computational Fluid Dynamics analysis of the flow of the Lead Bismuth Eutectic (LBE) target, resulting in optimized designs. The concept and hydrodynamic challenges of generating RIBs from a liquid-metal-loop target irradiated with a high-power primary beam are presented. The optimization of the target design has been conducted keeping in mind the need for a fast and efficient release of short-lived isotopes.This study shows that approximately 100ms after the proton pulse the irradiated liquid-metal is entirely and uniformly evacuated from the irradiation volume and spread in a shower of small droplets (100-μm radii), in order to reduce the diffusion length of isotopes. Solutions to deal with the typical cavitation risk due to the presence of low-pressure zones in the liquid have also been found and simulated.

Highlights

Applications of Radioactive Ion Beams (RIBs) are found in several fields of science, e.g. nuclear physics, fundamental interactions, and nuclear astrophysics [1]
LBE flows into the irradiation volume through its base section and is evacuated through a series of apertures uniformly distributed over the lower half of the cylinder lateral surface
Results of the Computational Fluid Dynamics (CFD) analysis are included in Fig. 8: velocityvectors are uniformly distributed in the irradiation volume and at evacuation to the diffusion volume

Summary

Introduction

Applications of Radioactive Ion Beams (RIBs) are found in several fields of science, e.g. nuclear physics, fundamental interactions, and nuclear astrophysics [1]. Because of their short halflives, production of exotic nuclei using off-line separation techniques is discarded, since the isotopes would completely decay before separation. The IFS method mostly makes use of high-energy nuclear beams impacting on a thin target and relies on the recoil of the reaction products in combination with magnetic or electrical fields to separate the isotopes of interest. In the ISOL method, the isotopes of interest are produced and released from a thick target, kept at high temperature, which often n Corresponding author at: Belgian Nuclear Research Centre (SCKCEN), serves as catcher to thermalize the reaction products. The isotopes are subsequently ionized, extracted and mass separated

Methods

Results

Discussion

Conclusion