Speaker
Enrique Ascasibar
(National Fusion Laboratory)
Description
During ITER and DEMO reactor operation the proposed Li-Pb blanket flow channel inserts made of SiC ceramic material will be exposed to both radiation and tritium. Absorption, diffusion, and desorption of tritium is expected to occur and these processes will strongly depend on the irradiation conditions, neutron flux, and purely ionizing radiation. Previous results have shown that marked deuterium absorption, associated with the formation of silicon deuterium bonding, occurs for SiC materials when both deuterium and sample are subjected to a radiation field, and that this radiation enhanced absorption strongly depends on both the displacement damage and the ionizing radiation field. In the work to be presented the roles played by irradiation temperature, dose rate, dose, and deuterium gas pressure have been addressed for reaction bonded SiC.
The samples have been irradiated making use of a special chamber with a 50 mm thick aluminium window mounted in the beam line of a Van de Graaff accelerator. The chamber, filled with deuterium gas at different pressures, contains a sample holder with an oven allowing one to heat the samples from room temperature up to 800 C. Both the deuterium gas and samples were irradiated with 1.8 MeV electrons at different dose rates, doses, gas pressures, and sample temperatures. Following irradiation each sample was remounted in another system which permitted one to linearly heat the sample and measure the release rate of any radiation induced absorbed deuterium as a function of temperature.
The results show that radiation induced deuterium absorption depends linearly on total ionizing dose and deuterium gas pressure, but not on dose rate. Behaviour with irradiation temperature is more complex, and clear changes in the deuterium thermal desorption are observed to occur depending on irradiation temperature. SIMS results for high temperature loaded RB SiC are consistent with radiation enhanced diffusion.
Co-authors
Alejandro Morono
(National Fusion Laboratory, CIEMAT, Madrid, Spain)
Enrique Ascasibar
(National Fusion Laboratory, CIEMAT, Madrid, Spain)
Eric Hodgson
(National Fusion Laboratory, CIEMAT, Madrid, Spain)
Fernando Sanchez
(National Fusion Laboratory, CIEMAT, Madrid, Spain)
Marina Verdu
(National Fusion Laboratory, CIEMAT, Madrid, Spain)
Marta Malo
(Fundación UNED-CIEMAT, Madrid, Spain)
