Speaker
Description
I.Ye. Kenzhina1,2, T.V. Kulsartov1, A.A. Shaimerdenov1,2, Ye.V. Chikhray1, S.K. Askerbekov1,2, M. Aitkulov2, Zh.A. Zaurbekova1
1Satbayev University, Almaty, Kazakhstan
2Institute of Nuclear Physics, Almaty, Kazakhstan
e-mail: kenzhina@physics.kz
The design of future fusion reactors involves the generation of tritium inside a breeder blanket. One of the most promising materials for the breeder blanket today is lithium ceramics. Tritium is formed in lithium under neutron irradiation by the reaction 6Li(n,α)T. This tritium is then extracted from the blanket by purge gas and returned to the fusion area, realizing the concept of a closed fusion cycle. Irradiation under fission reactor conditions is still one of the few available methods for in-situ estimation of tritium generation and release parameters from lithium-containing materials. In this work, based on a series of reactor experiments performed with two-phase lithium ceramics and LMT ceramics, a number of advantages of using the technique to investigate the generation and release of tritium when conducting experiments under vacuum pumping conditions of the samples under study have been identified. The main advantages of this method include:
• It is possible to fully control the composition of the gas phase in the chamber with samples, which greatly facilitates the analysis of possible reactions on the ceramic surface associated with the release of both tritium-containing molecules and helium;
• possibility of conducting experiments to study the release of tritium from lithium ceramics at a given change in the composition of gases in the chamber with samples;
• high sensitivity and practically no delay in recording changes in the gas phase composition (including tritium-containing molecules and helium) when changing various experimental parameters (such as sample temperature; reactor power, etc.)
A number of methodological complexities of reactor experiments with lithium ceramics under conditions of vacuum pumping of the studied samples are also analyzed:
• in particular, it was found that there are some limitations on the lower limit of the investigated temperatures of the ceramics, which is caused by the low thermal conductivity of pebble bed;
• also, when the samples are arranged in several layers in the pebble bed, there is a noticeable temperature gradient across the filling, which is difficult to measure and can often be estimated only by calculation;
• it is better to use high-resolution mass spectrometers in the 4-mass region to separate the signal for HT and helium molecules.
