D-depth profiling in as-implanted and annealed Li-based breeder blanket ceramics

Abstract

HIGHLIGHTS• Three solid breeder blanket candidates were D-implanted and characterized by NRA at different annealing temperatures.• Lithium containing silicate and titanate ceramics with ratio 2Li:Si, 3Li:Si and lLi:Ti were fabricated.• The fabricated ceramics exhibit different porosity, grain size and density.• The ceramics were implanted with D: a complete outgas was observed at T > 200 °C.• Surface is crucial for the release kinetics and grain boundaries represent an alternative path to porous for diffusion. ABSTRACTIn future power plants (i.e. DEMO), the nuclear fusion of hydrogen isotopes will be used for energy production. The behaviour of hydrogen isotopes in lithium-enriched ceramics for breeder blankets (BBs) is one of the most important items to be understood.In this paper we present the chemical, microstructural and morphological features of Li 4 Si0 4 , Li 2 Ti0 3 and a third ceramic candidate with a higher Li:Si proportion (3:1), implanted with D at an energy of 100 keV and at room temperature at a fluence of 1 x 10 17 cm 2 . The D depth-profile in as-implanted and annealed ceramics (at T < 200 °C) was characterised by Resonance Nuclear Reaction Analysis (RNRA). The RNRA data indicate that the total amount of D is retained at room temperature, while annealing at 100 °C promotes D release and annealing at T > 150 °C drives D to completely desorb from all the studied ceramics. D release will be discussed as a function of the microstructurural and morphological features of each material.

Thermally induced outdiffusion studies of deuterium in ceramic breeder blanket materials after irradiation

“…Although this is a reasonable explanation for surface adsorption processes, further experiments should be conducted to establish whether the crystalline structure influences those processes at higher temperature. This statement is supported by recent experimental results of electrical conductivity [personal communication] and diffusion [7] on D 2 implanted pellets. The mobility of ionic species is enhanced in m-LiTi rather that in o-LiSi due to its layered structure, which favors the diffusive processes involving intrinsic and radiation-induced defects.…”

“…Indepth profiles of remaining D 2 obtained using the Resonant Nuclear Reaction Analysis at variable annealing temperatures show the fast D 2 migration through the ceramic, but the blocking effect of surface. Trapping sites at ceramic surface were causing the blockage of gas desorption although the amount of released D2 was very small at temperatures as low as 200 • C [7].…”

3He Behaviour in Li2TiO3 Ceramics for Fusion Breeding Blanket Applications

“…Figure 4 also stress a fairly symmetrical implantation profile from f f the maximum to both sample surface and bulk a homogeneous, concluding that heating seems not affecting the 3 He gas distribution along the sample thickness. For comparison, previous results [13] on D-implantation are discussed. D behaviour with temperature was studied in the past also in a MTi matrix with marked differences in the microstructure compared with the material used during these experiments.…”

Study of the Effect of Two Phases in Li4SiO4–Li2SiO3 Ceramics on the Strength and Thermophysical Parameters

“…Over the past few years, great attention has been paid to developments in the field of blanket ceramics, the interest in which is due to the possibilities and prospects for their use in thermonuclear energy [ 1 , 2 , 3 ]. As is known, thermonuclear energy is one of the most promising industries that can become an alternative to hydrocarbon fuel and, also, unlike nuclear energy, does not contain a large amount of nuclear long-lived waste.…”