Search results for "Tritium"
showing 10 items of 165 documents
Tritium sorption and desorption from JET beryllium tiles under temperature, electron radiation and magnetic field
2008
Abstract Tritium release at annealing of samples cut from beryllium tiles exposed to D + D, D + T plasma in the Joint European Torus (JET) was investigated under 5 MeV fast-electron radiation at the dose rate 14 MGy h −1 and in a magnetic field of 1.7 T separately and simultaneously in order to evaluate possible effects of these factors. Abundances of chemical forms of tritium—molecular T 2 (44%), atomic T 0 (42%), and ionic T + (14%) and their distribution were determined in the plasma-exposed beryllium samples with lyomethods. Fast-electron radiation considerably increased the fractional tritium release at annealing by a factor of approximately 5. The magnetic field increased the fraction…
Tritium release from breeding blanket materials in high magnetic field
2007
Abstract Under the operating conditions of a fusion reactor, the blanket materials: ceramic and Be pebbles will be at a high temperature (up to 1123 K), under action of intense radiation (up to 10 19 n m −2 s −1 ) and magnetic field (MF) up to 7–10 T. In order to introduce action of radiation and MF in post-irradiation investigations of the tritium release from the blanket materials, a special rig for thermo-annealing of pre-irradiated samples at a high temperature up to 1120 K under irradiation with fast electrons of 5 MeV and dose rate 14 MGy/h in MF up to 1.7 T was used for this study. A delay of the tritium release in MF of 2.4 T at thermo-annealing of the lithium orthosilicate Li 4 S…
Glovebox atmosphere detritiation process using gas separation membranes.
2003
Abstract The use of gas separation membranes in atmospheric detritiation systems has been studied. The main advantage of this new process is to reduce the number and/or the size of the equipment in comparison to conventional tritium removal systems. Owing to the constraints linked to tritium handling, the separation performances of several commercial hollow fiber organic membranes have been analyzed, under various operating conditions, with hydrogen/nitrogen or deuterium/nitrogen mixtures. The experiments are performed with small quantities of hydrogen or deuterium (5000 ppm). The experimental results allow to evaluate the separation efficiency of these membranes and to determine the approp…
Experiments on tritium generation and yield from lithium ceramics during neutron irradiation
2021
Abstract The vacuum extraction method with a mass spectrometry registration of tritium is presented in paper. It can provide a full-range analysis of gas phase composition in the chamber with samples under neutron irradiation. Lithium ceramics Li2TiO3 in the form of pebbles with lithium enrichment on 6Li isotope of 96% was examined. The paper shows the results of reactor experiments on study the extraction of tritium-containing molecules from lithium ceramics Li2TiO3 at various temperatures and reactor power levels at the WWR-K research reactor (Almaty, Kazakhstan). The time dependences of tritium yield from the ampoule with ceramics during reactor irradiation were obtained. Near-surface co…
Self radiolysis of tritiated water
2003
The mechanism of water radiolysis implies several reactions and depends on many parameters such as the radiation characteristics (type of radiation, energy…), the temperature and the chemical composition of irradiate water. Thus it is very difficult to foresee, without experimental data, the overall effect of these parameters. If radiolysis of pure water under γ rays or α particles has been widely studied, it is not the case for self radiolysis of tritiated water (low energy β− particles radiation). In order to fill this lack of experimental knowledge and to understand the radiolysis of stored tritiated water produced in tritium plants, we studied the evolution of hydrogen and oxygen concen…
Characterisation and radiolysis of modified lithium orthosilicate pebbles with noble metal impurities
2017
Modified lithium orthosilicate (Li4SiO4) pebbles with additions of titanium dioxide (TiO2) are suggested as an alternative tritium breeding ceramic for the European solid breeder test blanket module. The noble metals – platinum (Pt), gold (Au) and rhodium (Rh), can be introduced into the modified Li4SiO4 pebbles during the melt-based process, due to the corrosion of Pt-Rh and Pt-Au alloy crucible components. In this study, the surface microstructure, chemical and phase composition of the modified Li4SiO4 pebbles with different contents of the noble metals was analysed. The influence of the noble metals on the radiolysis was evaluated after irradiation with accelerated electrons (E = 5 MeV),…
Behaviour of tritium in breeding materials
2005
Abstract The tritium release from ceramic materials of the HCPB under real DEMO operating conditions will depend not only on temperature and neutron flux but also on an intense magnetic field (MF) of 7–9 T. The delay in the tritium release induced by the MF is proportional to the grain size of the ceramics, the squared MF intensity and the abundance ratio of charged tritium forms (T + , T − ) in the grain volume of the ceramics. The effect of MFs of different intensity on the tritium release from the Li 4 SiO 4 pebbles irradiated in the EXOTIC-8 experiment (neutron fluence 2.4 × 10 25 n m −2 , irradiation temperature up to 700 K) was investigated in this study. As a result of the irradiati…
Influence of chemisorption products of carbon dioxide and water vapour on radiolysis of tritium breeder
2014
Abstract Lithium orthosilicate pebbles with 2.5 wt% excess of silica are the reference tritium breeding material for the European solid breeder test blanket modules. On the surface of the pebbles chemisorption products of carbon dioxide and water vapour (lithium carbonate and hydroxide) may accumulate during the fabrication process. In this study the influence of the chemisorption products on radiolysis of the pebbles was investigated. Using nanosized lithium orthosilicate powders, factors, which can influence the formation and radiolysis of the chemisorption products, were determined and described as well. The formation of radiation-induced defects and radiolysis products was studied with …
X-ray induced defects in advanced lithium orthosilicate pebbles with additions of lithium metatitanate
2019
Abstract Advanced lithium orthosilicate (Li4SiO4) pebbles with additions of lithium metatitanate (Li2TiO3) as a secondary phase have attracted international attention as an alternative solid-state candidate for the tritium breeding in future nuclear fusion reactors. In this research, the generation of radiation-induced defects in the Li4SiO4 pebbles with various contents of Li2TiO3 was analysed in-situ by X-ray induced luminescence technique. After irradiation with X-rays, the accumulated radiation-induced defects in the Li4SiO4 pebbles were studied by electron spin resonance, thermally stimulated luminescence and absorption spectrometry. On the basis of the obtained results, it is conclude…
Study of tritium and helium generation and release from lead-lithium eutectics Li15.7Pb under neutron irradiation
2019
Abstract This paper describes the experiments on study of tritium and helium generation and release processes from lead-lithium eutectics Li15.7Pb. The irradiation was performed at the IVG.1M research reactor at 6 MW of thermal power. The irradiation temperature increased step by step from 225 to 550 °C. A qualitative assessment of the experimental results showed that as the temperature rises above 390 °C, the tritium flux from the sample consisting of T2 and HT molecules decreases. It was concluded that the observed effect is similar to the previously observed one for lead-lithium eutectics with Li17Pb83 composition.