Skip to Main content Skip to Navigation
Theses

ÉTUDES SPECTROSCOPIQUES DES VERRES IRRADIES : APPLICATION EN DOSIMÉTRIE NUCLÉAIRE

Abstract : A dosimetry system for the industry must be easy to use, quick to measure and at a reduced cost. Among these dosimetric systems, the RPE / alanine system is internationally recognized as a method of reference in metrology of ionizing radiation. This technique is generally employed because of its wide range of measurement, relatively low uncertainty and non-destructive measurement. However, its high cost reduces its use in routine applications. It is in this context that the present work aims to study the effects of ionizing radiation on silicate glasses in order to develop a new dosimetric system that is simple, precise, stable and inexpensive. Indeed, changes in the mechanical, optical and paramagnetic properties of glasses once subjected to ionizing radiation have been widely studied for several decades due to the multiple applications of this material in particular as a radioactive waste containment matrix. The prediction of the long-term behavior, physical aging under irradiation, of this glass is paramount. As early as the 1950s, studies have focused on ways to avoid obscuring glasses used in windows of nuclear reactors or hot cells and optical devices. Recently, much work has been focused on the application of radiation-induced color to develop a recyclable glass in the glass industry which is of great economic and environmental interest. In this thesis work we have studied, by optical spectroscopy and electron paramagnetic resonance (EPR), the irradiation effects of γ-radiation and accelerated electrons on silicate glasses to study the nature, formation and relaxation of different induced defects. The irradiated samples show the appearance of two absorption bands that can be resolved around 410 and 600 nm. The visible radiation induced absorption in silica glasses has been attributed to a 2p orbital entrapped hole of non-bridging oxygen NBOHC (Non Bridging Oxygen Hole Center). We then introduced silver into the glass surface using the ion exchange technique for different conditions of concentration and time. The ionically exchanged samples were subjected to different heat treatments. The absorption spectra of these samples were measured in the 300-600 nm range and used to identify the various states of silver existing in these glasses, determine the range of stability of each of the identified states, and determine the size of the aggregates of silver formed. We then subjected ionically exchanged samples to gamma irradiation and thermal treatments. We have shown that irradiation can neutralize a part of Ag + and create defects (NBOHCs) whose number increases enormously depending on the amount of silver introduced into the glass by ion exchange. The silver aggregates were not formed until after heat treatment at 550 ° C for 20 min. By increasing the annealing time, the continuous growth and size of the aggregates increases to critical dimensions. The distance between neighboring aggregates remains large so that a larger size aggregate can not develop by intergranular diffusion processes. We also found that gamma radiation significantly affects the size of silver aggregates. Indeed, the diffusion of silver in the glass increases by several orders of magnitude when the sample is irradiated before undergoing heat treatment. On the other hand we have found that the size of the aggregates depends on the value of the dose of gamma radiation. Contrary to expectations, it has been shown that doses above 20 kGy do not favor the formation of aggregates of larger sizes. The present study indicated that the optical absorption response of this type of γ-ray and accelerated electron glass can be reasonably well measured in the 0.1-50 kGy range. Tests on this type of glass have shown its good performance. This material is reliable as a dosimeter and can be used to measure doses between 0.1-17 kGy by ensuring that environmental conditions are carefully controlled during its use.
Complete list of metadatas

Cited literature [153 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02092744
Contributor : Khaled Farah <>
Submitted on : Monday, April 8, 2019 - 2:16:34 PM
Last modification on : Sunday, January 19, 2020 - 11:22:02 AM

File

Thèse Khaled Farah.pdf
Files produced by the author(s)

Licence


Public Domain

Identifiers

  • HAL Id : tel-02092744, version 1

Citation

Kh. Farah. ÉTUDES SPECTROSCOPIQUES DES VERRES IRRADIES : APPLICATION EN DOSIMÉTRIE NUCLÉAIRE. Instrumentations et Détecteurs [physics.ins-det]. Université de Monastir (Tunisie), 2009. Français. ⟨tel-02092744⟩

Share

Metrics

Record views

67

Files downloads

1236