Tritium absorption/desorption in ITER-like tungsten particles

A El-Kharbachi,S Garcia-Argote,F Martin,M Redolfi,C Grisolia,F Miserque,J Chêne,V Malard,L Marchetti,D Vrel,B Rousseau

doi:10.1016/j.ijhydene.2014.05.023

Abstract

Abstract Tritium retention in plasma facing materials such as tungsten is a major concern for future fusion reactors. During ITER operating mode, the reactor could generate tritiated tungsten dust-like particles which need to be characterized in terms of amount of trapped tritium, tritium source and radiotoxicity. This study is focused on the preparation and characterization of tungsten particles and on a comparative analysis of tritium absorption/desorption kinetics in these particles and in massive samples. An original gas phase thermal charging procedure was used successfully for tritium incorporation in tungsten powders and massive samples. Much larger tritium amounts are incorporated in W particles than in massive samples indicating important surface effects on tritium absorption, desorption and trapping in W. Tritium desorption from particles occurred at different temperatures related with different interactions on the particles surface and in the bulk; the tritium behavior in massive samples was also shown to depend on the metal microstructure. According to these experimental results tritium absorption/desorption in W particles may have important implications on tritium management in ITER reactor.

Highlights

Assessments related to WeH system for applications in thermonuclear reactors are in demand with the launch of the ITER international project, the most important international research project on energy
We report here the results obtained for two different batches of tungsten particles L1 and L2 having two different specific surface area (SSA), respectively of 15.5 and 7.5 m2/g, in order to evidence the influence of this parameter
Different desorption tests were conducted both at room temperature and high temperature on well characterized “ITER like” W particles and massive samples showing a different behavior of tritium in particles and in massive samples

Summary

Introduction

Assessments related to WeH system for applications in thermonuclear reactors are in demand with the launch of the ITER international project, the most important international research project on energy. The walls of the tokamak prototypes consisted mainly of carbon material in which significant trapping of tritium occurred, inducing the release of tritiated carbon particles with activities sometimes higher than 1 GBq/g [1]. During the 2He3H plasma as in the ITER project, the reactors could generate tritiated W dust which need to be characterized and their properties assessed, in terms of amount of trapped tritium and tritium source. Their radiotoxicity has to be approached in further investigations. It is necessary to evaluate their toxicity degree, where the data are lacking as the operating tokamak prototypes with tungsten do not exist yet

Results

Discussion

Conclusion