29th Symposium on Fusion Technology (SOFT 2016)

P3.146 H isotope thermo-diffusion in structural materials

7 Sep 2016, 11:00

1h 20m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 146

Poster H. Fuel Cycle and Breeding Blankets P3 Poster session

Speaker

Marta Malo (Fundación UNED-Ciemat)

Description

Tritium permeation through containment structures is an important factor for safety and design analysis of fusion energy systems. This process controls several key aspects of the system performance, including the amount of radioactive tritium released to environment, the requirements on tritium breeding ratio, the tritium recycling from the first wall, and it influences the selection of technologies adopted in the design of several components As a consequence the characterization of permeation and diffusion process and the determination of relevant material properties is a priority for the design of breeding blanket systems.  Considerable data is available for hydrogen isotope diffusion and permeation in different metals as a function of temperature. However, in the case of breeding blankets, these materials will be additionally subjected to a temperature gradient between the inner and outer surfaces of the coolant circulating channels. Although design analysis has shown that this factor could have an important impact on the system performance [1,2],  permeation driven by thermal gradients (also referred to as Soret effect) has not in general been included in either experimental studies, or modelling of blanket systems, and must be assessed. The THERMO-PERM facility has been developed for this purpose as an external extension to the CIEMAT Van de Graaff electron accelerator laboratory. This paper describes the experimental system, in particular the new permeation chamber whose cooling/heating system allows one to produce thermal gradients up to about 120 ºC in 1 mm thick samples and measure hydrogen isotope (H2 and D2) permeation. Experimental results obtained for deuterium in 316 L stainless steel are also discussed. [1] O. V. Ogorodnikova, et al, Journal of Nuclear Materials 273 (1999) 66-78. [2] G. R. Longhurst, Journal of Nuclear Materials 131 (1985) 61-69.