INVESTIGATIONS of the CHEMICAL COMPATIBILITY of RHENIUM with URANIUM DIOXIDE at ELEVATED TEMPERATURES by DJAMEL KAOUMI a THESIS
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INVESTIGATIONS OF THE CHEMICAL COMPATIBILITY OF RHENIUM WITH URANIUM DIOXIDE AT ELEVATED TEMPERATURES By DJAMEL KAOUMI A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2001 Copyright 2001 by Djamel Kaoumi To Ourdia Alouache ACKNOWLEDGMENTS I would like to thank Dr. Samim Anghaie for supporting me during these two years at INSPI. His trust and encouragement were very much appreciated. I would like also to thank Dr. Edward T. Dugan for his support and for being so available as a teacher throughout my graduate work at the University of Florida. I am grateful to Dr. Rajiv K. Singh from the Materials Sciences and Engineering department for his support as a teacher and for taking time to be part of my committee. I would also like to thank everyone at INSPI (Lynne, Travis, Blair, Gary, Vadi) for their valuable help and kindness and for the agreeable ambiance. I would also like to thank my mother and family for their continuous support, and my friends whose support was very encouraging. iv TABLE OF CONTENTS page ACKNOWLEDGMENTS .............................................................................................iv LIST OF TABLES ........................................................................................................vii LIST OF FIGURES......................................................................................................viii 1 INTRODUCTION AND BACKGROUND..................................................................1 The 710-Reactor Program............................................................................................2 Latta’s Study on Solidus Liquidus Temperatures of UO2±x...........................................6 2 RHENIUM ..................................................................................................................8 Rhenium’s Physical Properties.....................................................................................9 Ductility of Rhenium .................................................................................................10 Workability of Rhenium ............................................................................................11 Fabrication of Rhenium Parts.....................................................................................12 Physicomechanical Properties of Rhenium.................................................................13 Rhenium as an Alloying Element...............................................................................15 Interactions of Rhenium with Other Elements............................................................16 Chemical Properties...................................................................................................17 3 THEORETICAL AND EXPERIMENTAL INVESTIGATIONS ON THE COMPATIBILITY BETWEEN URANIUM DIOXIDE AND RHENIUM................21 Thermodynamic Considerations: Predictions Based on F*A*C*T code .....................21 Experimental Work....................................................................................................27 Principle of the Method..........................................................................................27 Materials/Protocol..................................................................................................28 Results...................................................................................................................30 Sample 1............................................................................................................30 Sample 2............................................................................................................37 Conclusions ...............................................................................................................42 v APPENDICES A: X-RAY POWDER DIFFRACTION ANALYSIS .....................................................44 B: ENERGY-DISPERSIVE X-RAY SPECTROMETRY (EDS) ...................................46 C: SAMPLE 3 ...............................................................................................................50 LIST OF REFERENCES...............................................................................................53 BIOGRAPHICAL SKETCH .........................................................................................55 vi LIST OF TABLES Table page 1: Results obtained with the F*A*C*T code for the Re/O2 system at different high temperatures..................................................................................................................24 2: Results obtained with the F*A*C*T code for the rhenium-oxygen system with excess oxygen, at different high temperatures...........................................................................25 3: Results obtained with the F*A*C*T code for the Re/UO2 system at different high temperatures..................................................................................................................25 vii LIST OF FIGURES Figure page 1: Ductile-to-brittle transition behavior of refractory metal versus temperature. .................11 2: Ultimate Tensile Strength (UTS) of refractory metals (left). Creep-Rupture Strength of refractory metals (right) (from Bryskin B. D. 1992).......................................................14 3: Rate of corrosion of refractory metals in air. ..................................................................20 4: Rotary tumbler used to mix the Re powder with the UO2 powder...................................28 5: Induction-furnace chamber used for sintering the samples. ............................................29 6: Inductive coil and heated susceptor radiating inside the furnace chamber.......................30 7: Tungsten susceptor after sintering Sample 1 at 2500 K for 10 hours...............................31 8: X-ray powder diffraction pattern of the pre-sintered of Re and UO2 powders................33 9: X-ray powder diffraction pattern of the sintered mixture of Re and UO2 powders left inside the crack..............................................................................................................33 10: Growth outside of the crack. ........................................................................................34 11: X-ray powder diffraction pattern of the growth outside the crucible. ............................34 12: X-ray powder diffraction pattern of the top region of sample 1. ...................................35 13: Dark deposit on the coil, after sintering the tungsten crucible the first time. .................36 14. XRD pattern of the deposit found on the furnace chamber walls. .................................36 15: Tungsten susceptor after the sintering of sample 2. ......................................................37 16: X-ray powder diffraction pattern of the pre-sintered mixture of UO2 and Re powders. .39 17: X-ray powder diffraction pattern of the bottom region of the sample............................39 18: X-ray powder diffraction pattern of the middle region of the sample............................40 viii 19: Back-scattered scanning electron micrograph showing compositional contrast of Re- UO2 powders sintered for 10 hr. at 2500 K...................................................................41 20: Back-scattered scanning electron micrograph showing compositional contrast of Re- UO2 powders sintered for 10 hr. at 2500 K...................................................................41 21: Line scan operated across the region showed on Figure 19...........................................42 22: Crucible cap surrounded by oxide deposits. .................................................................51 23: Coil after removal; a blue-black deposit on the walls was observed similar to the deposit..............................................................................................................51 24: X-ray analysis pattern of the top part of the failed sample. ...........................................52 25: X-ray analysis pattern of the bottom region of the sample. ...........................................52 ix Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Master of Science INVESTIGATION OF THE CHEMICAL COMPATIBILITY OF RHENIUM WITH URANIUM DIOXIDE AT VERY HIGH TEMPERATURES By Djamel Kaoumi August 2001 Chairman: Samim Anghaie Major Department: Nuclear and Radiological Engineering Department Because of its high melting point, outstanding ductility, good strength and creep behavior, rhenium has been a very good candidate for high-temperature applications in the field of aerospace. It is particularly suitable for application as structural material in space nuclear reactor cores. Rhenium is also proposed as fuel cladding material for high temperature space reactors. It has also been proposed as a liner for the fuel pin in a space power reactor design (SP-100 program) because of its high neutron absorption cross section that could make the reactor subcritical under a hypothetical water submersion accident. Despite all positive high temperature properties, Rhenium lacks corrosion resistance in the oxidation environment. As a cladding material for uranium dioxide fuel pellets, no chemical interaction between the two materials is acceptable. The purpose of x this study is to investigate chemical compatibility between urania and rhenium