6533b873fe1ef96bd12d55fa

RESEARCH PRODUCT

Accumulation of radiation defects and products of radiolysis in lithium orthosilicate pebbles with silicon dioxide additions under action of high absorbed doses and high temperature in air and inert atmosphere

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Abstract One of the technological problems of a fusion reactor is the change in composition and structure of ceramic breeders (Li 4 SiO 4 or Li 2 TiO 3 pebbles) during long-term operation. In this study changes in the composition and microstructure of Li 4 SiO 4 pebbles with 2.5 wt% silicon dioxide additions, fabricated by a melt-spraying process, were investigated after fast electron irradiation ( E  = 5 MeV, dose rate up to 88 MGy h −1 ) with high absorbed dose from 1.3 to 10.6 GGy at high temperature (543–573 K) in air and argon atmosphere. Three types of pebbles with different diameters and grain sizes were investigated. Products of radiolysis were studied by means of FTIR and XRD. TSL and ESR spectroscopy were used to detect radiation defects. SEM was used to investigate structure of pebbles. Experiments showed that Li 4 SiO 4 pebbles with a diameter of 500 μm had similar radiation stability as pebbles with diameter α 10.56 of the lithium orthosilicate pebbles at an absorbed dose of 10.56 GGy in air atmosphere is 1.5% and 0.15% at irradiation in dry argon. It has been suggested that changes of radiation stability of lithium orthosilicate pebbles in air atmosphere comparing with irradiated pebbles in argon atmosphere is effect of chemical reaction of lithium orthosilicate surface with air containing – H 2 O and CO 2 in irradiation process. As well as it has been suggested that silicon dioxide – lithium metasilicate admixtures do not affect formation mechanism of radiation defect and products of radiolysis in lithium orthosilicate pebbles.