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https://olympias.lib.uoi.gr/jspui/handle/123456789/39598| Title: | Investigation of neutron irradiation effects on the radiological and structural properties of tungsten materials for fusion energy applications Μελέτη της επίδρασης της ακτινοβολίας νετρονίων στις ραδιολογικές και δομικές ιδιότητες υλικών βολφραμίου με εφαρμογές στην τεχνολογία σύντηξης |
| Institution and School/Department of submitter: | Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών |
| Subject classification: | Nuclear Physics Material Physics |
| Keywords: | Tungsten,Neutron irradiation,Nuclear fusion,Plasma-facing materials,Transmutation products,γ-spectroscopy,FISPACT-II,Positron annihilation lifetime spectroscopy,Total dislocation line density,Effective void length density |
| URI: | https://olympias.lib.uoi.gr/jspui/handle/123456789/39598 |
| Table of contents: | List of Tables 8 List of Figures 9 Table of abbreviations 12 List of Publications 14 Participation in Conferences 15 Abstract 16 Περίληψη 19 Keywords 22 1 Introduction 23 2 Materials and Neutron Irradiation 27 2.1 Tungsten samples 27 2.2 Neutron Irradiation 29 2.3 Neutron fluence and dpa 31 3 Neutron irradiation induced defects 34 3.1 Mechanisms of Defect Formation 34 3.1.1 Neutron-atom interaction 34 3.1.2 Displacement Cascade 35 3.1.3 Radiation damage quantification 35 3.2 Types of defects 37 3.2.1 Lattice defects 37 3.2.2 Transmutation reactions 40 4 γ-Spectroscopy 42 4.1 γ radiation 42 4.2 γ-Spectroscopy Methodology 46 4.2.1 Theoretical background 46 4.2.2 Experimental Setup 48 4.2.3 System Calibration 49 4.2.4 Spectrum Analysis 53 5 Neutronic Numerical Calculations 59 5.1 Representative neutron spectrum 59 5.2 MCNP calculations 62 5.2.1 MCNP geometry 62 5.2.2 Neutron spectrum reproduction 63 5.2.3 Neutron fluence validation 65 5.3 FISPACT-II inventory code 66 6 Neutron Activation Analysis Results 68 6.1 Transmutation products of W 68 6.2 Pathway analysis 69 6.3 Analytical evaluation of irradiated W samples 70 6.3.1 Transmutation products 70 6.3.2 Data Validation 73 6.3.3 Fluence correction 77 6.3.4 Discussion 79 6.4 Spatial homogeneity of W samples 82 7 Positron Annihilation Lifetime Spectroscopy 84 7.1 Introduction 84 7.2 Positrons in matter 84 7.2.1 Positron Sources 84 7.2.2 Positron Implantation Depth 86 7.2.3 Mechanisms of positron trapping 90 7.3 Experimental Methodology and Instrumentation 96 7.3.1 Experimental Setup 96 7.3.2 System Calibration 99 7.3.3 System Resolution 101 7.3.4 Source Correction 103 8 PALS results 105 8.1 Unirradiated materials 105 8.2 Irradiated materials 107 8.2.1 Exponential Model Analysis Results 107 8.2.2 Trapping Model Analysis Results 119 8.3 General Discussion 130 9 Summary and Conclusions 137 10 References 141 |
| Appears in Collections: | Διδακτορικές Διατριβές - ΦΥΣ |
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|---|---|---|---|---|
| PhD_Thesis_Chatzikos.pdf | 5.49 MB | Adobe PDF | View/Open |
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