Fabrication of zirconia based ceramics by internal gelation for conversion of trivalent actinides [Elektronische Ressource] / vorgelegt von Gael Benay

Benay

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2008
• Nombre de lectures: 37
• Langue: Deutsch
• Poids de l'ouvrage: 10 Mo

Extrait

Fabrication of zirconia based ceramics
by internal gelation for conversion of
trivalent actinides


Von der Fakultät für Georessourcen und Materialtechnik
der Rheinisch-Westfälischen Technischen Hochschule Aachen

zur Erlangung des akademischen Grades eines
Doktors der Ingenieurwissenschaften

genehmigte Dissertation
vorgelegt von Dipl.-Ing


Gael Benay


aus Pessac, Frankreich

Berichter: Univ.-Prof. Dr.rer.nat. Reinhard Odoj
Univ.-Prof. Dr.rer.nat. Rainer Telle


Tag der mündlichen Prüfung: 16. Mai 2008

Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfugbar
















Fabrication of zirconia based ceramics
by internal gelation for conversion
of trivalent actinides

Gael Benay







































Berichte des Forschungszentrums Jülich ; 4283
ISSN 0944-2952
Institut für Energieforschung (IEF)
Sicherheitsforschung und Reaktortechnik (IEF-6) Jül-4283

D 82 (Diss., RWTH Aachen, 2008)

Vollständig frei verfügbar im Internet auf dem Jülicher Open Access Server (JUWEL)
unter http://www.fz-juelich.de/zb/juwel

Zu beziehen durch: Forschungszentrum Jülich GmbH · Zentralbibliothek, Verlag
D-52425 Jülich · Bundesrepublik Deutschland
02461 61-5220 · Telefax: 02461 61-6103 · e-mail: [e-mail]
2 Table of contents

1. Abstract ..........................................................................................................................5
2. Introduction ....................................................................................................................9
2.1 The current nuclear fuel cycle ...............................................................................11
2.1.1 Front end.......................................................................................................12
2.1.2 Spent fuel......................................................................................................13
2.1.3 Back end .......................................................................................................13
2.2 Radiotoxicity ........................................................................................................14
2.2.1 Partitioning of actinides.................................................................................17
2.2.1.1 Hydrometallurgical separation...................................................................17
2.2.1.2 Pyrochemistry method...............................................................................19
2.2.2 Transmutation ...............................................................................................20
2.2.3 New innovative fuel cycles............................................................................22
2.3 Fuels and inert matrix............................................................................................24
2.3.1 Material studies on fuels and inert matrices ...................................................24
2.3.2 Synthesis methods of inert matrices adapted for minor actinides....................28
2.3.2.1 General methods........................................................................................28
2.3.2.2 Sol-gel methods.........................................................................................30
2.3.3 Status of internal gelation ..............................................................................33
3. Scope of the work.........................................................................................................35
4. Experimental part .........................................................................................................37
4.1 Potentiometric titrations and co-precipitation experiment ......................................37
4.1.1 Potentiometric titrations ................................................................................37
4.1.2 Co-precipitation experiment ..........................................................................37
4.2 Viscosimetry and determination of the gelation temperature..................................38
4.3 Fabrication of kernels and pellets ..........................................................................38
4.3.1 Preparation of broths .....................................................................................39
4.3.2 Kernels fabrication ........................................................................................41
4.3.3 Kernels washing, drying and thermal treatment .............................................41
4.3.4 Pellets pressing and sintering.........................................................................42
4.4 Equipment and characterization methods ..............................................................43
4.4.1 ICP-MS measurements..................................................................................43
4.4.2 Thermal analysis ...........................................................................................43
4.4.3 Crystallization studies ...................................................................................44
4.4.3.1 Lattice parameter.......................................................................................44
4.4.3.2 Relative crystallinity degree.......................................................................45
4.4.4 Structure analysis by microscopy...................................................................45
4.4.5 Density measurements...................................................................................46
4.4.6 Dilatometry measurements ............................................................................47
4.5 Chemicals, materials and apparatus.......................................................................47
4.5.1 Chemicals .....................................................................................................47
4.5.2 Materials .......................................................................................................47
4.5.3 Other apparatus .............................................................................................48
5. Results and Discussion .................................................................................................51
5.1 Introduction ..........................................................................................................51
5.2 Preliminary studies on gelation .............................................................................52
5.2.1 Study of metal hydrolysis: co-precipitation experiment .................................52
5.2.2 Potentiometric titrations: effect of urea on metal ions ....................................54
3 5.2.3 Kinetic effects of HMTA decomposition and influence of urea and temperature
......................................................................................................................56
5.2.4 Determination of gelation temperature by viscosimetry .................................60
5.2.5 Determination of gelation yields....................................................................64
5.2.6 Thermal analysis of gels................................................................................68
5.3 Preparation and characterization of kernels ...........................................................71
5.3.1 Fabrication of kernels with different metal contents.......................................71
5.3.1.1 Thermal analysis of kernels .......................................................................72
5.3.1.2 Crystallization behavior of kernels.............................................................73
5.3.1.3 Structure of kernels....................................................................................76
5.3.2 Fabrication of kernels with fixed metal concentration, influence of urea and
HMTA ......................................................................................................................78
5.3.2.1 Thermal analysis of kernels .......................................................................79
5.3.2.2 Thermal degradation of urea, HMTA and a mixture of both products ........81
5.3.2.3 Thermal analysis of kernels under inert atmosphere...................................84
5.3.2.4 Crystallization behavior of kernels and conclusions on losses....................85
5.3.2.5 Surface structure of kernels .......................................................................88
5.3.2.6 Fabrication of kernels with a reduced size by using a vibrating nozzle.......90
5.3.3 Fabrication of kernels with reduced metal concentration................................91
5.3.3.1 Thermal analysis and surface structure characterization of the kernels .......92
5.3.3.2 Study of the influence of the quantities of urea and HMTA in the broth on
met