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Projects / Programmes source: ARIS

Raziskava zadrževanja in sproščanja plinastega devterija s kovin primernih za ITER (Slovene)

Research activity

Code Science Field Subfield
2.09.05  Engineering sciences and technologies  Electronic components and technologies  Vacuum technologies 
Evaluation (rules)
source: COBISS
Researchers (1)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  20335  PhD Bojan Zajec  Civil engineering  Head  2009 - 2011  184 
Organisations (1)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,882 
Significance for science
The proposed infusion/outgassing method for determination of the deuterium retention turned out to be unreliable for samples made of materials (in our case Be and W) with low H isotope solubility (low retention). The main reason lies in the "blank run" being almost equal to the measurement with sample – retention and isotope exchange occurring at the hot walls of the envelope represent the major source of measured signal, hence bad true signal/background ratio. Presence of HD molecules is naturally expected, however they can originate also from the hot filament of mass spectrometer, thus making the quantitative analysis of H/D gas mixture unreliable. Another drawback is the need for low H concentration in sample that requires long preprocessing (H outgassing) of sample. Only AISI316 sample was successfully measured, while the results of Be and W sample (all ITER-grade) bear considerable error. Consequently we turned to hydrogen permeation measurements and achieved a high degree of competence in hydrogen permeation measurements through two-layer membrane (thick substrate coated with thin film). Literature survey reveals no prior publications on hydrogen permeability measurements through Be, W, Be-W and SiN films. It is virtually impossible to determine the hydrogen permeability of highly impermeable materials using a thick bulk membrane. The reasons are extremely long transient time and permeation flux below any reasonable detection limit. We managed to overcome these obstacles by measuring the hydrogen permeation through a thin film of such material deposited on a mechanically stable and well-permeable substrate (in our case Eurofer steel) thanks to our experimental capabilities, skill and knowledge. Hydrogen permeation measurements through two-layer membrane have been rather rarely applied due to complicated and even lacking models for extraction of hydrogen interaction parameters from experimental data. Our expertise on hydrogen kinetics models and development of new ones provides us an essential advantage.
Significance for the country
Our prediction of the retention rate of tritium in cca.1000m2 of ITER vacuum vessel is the following: even the highest recorded value for deuterium retention during a 24 h exposure (at p = 0.1 mbar and 400°C) represents less than 2 g of tritium equivalent. This quantity does not represent a noticeable fraction of all allowed tritium inventory within the torus which is at present set at 700g. Our investigations on hydrogen permeation through thin Be, W and mixed Be-W films reveal a significant deviation from a Be and W bulk properties regarding hydrogen interaction parameters. The project group is also one of a few research groups dealing with molecular hydrogen (and its isotopes) interactions with current ITER related materials within the ITER-research framework. Both represent an important contribution from Slovenia. As a member of EU and signatory of an agreement with EURATOM, the European Atomic Energy Community that secured long-term R&D co-operation across the European Union in the field of fusion, Slovenia thus fulfills its participation in the research for the ITER fusion reactor.
Most important scientific results Annual report 2010, final report, complete report on dLib.si
Most important socioeconomically and culturally relevant results Annual report 2009, 2010, final report, complete report on dLib.si
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