Ceramic Immobilisation Options for Technetium

2012 ◽  
Vol 1518 ◽  
pp. 111-116 ◽  
Author(s):  
Martin C. Stennett ◽  
Daniel J. Backhouse ◽  
Colin L. Freeman ◽  
Neil C. Hyatt
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
High Mobility ◽  
X Ray Diffraction ◽  
Host Matrix ◽  
X Ray ◽  
Separate Fraction ◽  
X Ray Absorption ◽  
Snf Reprocessing

ABSTRACTTechnetium-99 (99Tc) is a fission product produced during the burning of nuclear fuel and is particularly hazardous due to its long half life (210000 years), relatively high content in nuclear fuel (approx. 1 kg per ton of SNF), low sorption, and high mobility in aerobic environments. During spent nuclear fuel (SNF) reprocessing Tc is released either as a separate fraction or in complexes with actinides and zirconium. Although Tc has historically been discharged into the marine environment more stringent regulations mean that the preferred long term option is to immobilise Tc in a highly stable and durable matrix. This study investigated the feasibility of incorporating of Mo (as a Tc analogue) in a crystalline host matrix, synthesis by solid state synthesis under different atmospheres. Samples have been characterised with X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray absorption spectroscopy (XAS).

Elastic strains in polycrystalline UO2 samples implanted with He: micro Laue diffraction measurements and elastic modeling

2013 ◽  
Vol 1514 ◽  
pp. 125-130
Author(s):  
Axel Richard ◽  
Etienne Castelier ◽  
Herve Palancher ◽  
Jean-Sebastien Micha ◽  
Philippe Goudeau
Keyword(s):  
Spent Nuclear Fuel ◽  
Simple Expression ◽  
X Ray Diffraction ◽  
Laue Diffraction ◽  
X Ray ◽  
Elastic Stresses ◽  
Long Term Storage ◽  
Macro Scale ◽  
Grain Orientations

Abstract:In the framework of the study of long-term storage of the spent nuclear fuel, polycrystalline UO2 samples have been implanted with He ions. The thin implanted layer, close to the free surface is subjected to elastic stresses which are studied by x-ray diffraction (micro Laue diffraction) and a mechanical modeling. A simple expression of the displacement gradient tensor has been evidenced; it concerns only three terms (ε3, ε4 and ε5) which strongly evolve with considered grain orientations. Finally, we show that results obtained with micro diffraction are in very good agreement with conventional x-ray diffraction measurements done in laboratory at macro scale.

scholarly journals Radiation damage from long-term alpha particle bombardment of silicates – a microfocus XRD and Fe K-edge XANES study

2015 ◽  
Vol 79 (6) ◽  
pp. 1455-1466 ◽  
Author(s):  
W. R. Bower ◽  
C. I. Pearce ◽  
G. T. R. Droop ◽  
J. F. W. Mosselmans ◽  
K. Geraki ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Ion Irradiation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Radiation Fields ◽  
Mineral Phases ◽  
Particle Damage ◽  
X Ray Absorption ◽  
Defect Densities

AbstractA detailed understanding of the response of mineral phases to the radiation fields experienced in a geological disposal facility (GDF) is currently poorly constrained. Prolongued ion irradiation has the potential to affect both the physical integrity and oxidation state of materials and therefore may alter a structure's ability to react with radionuclides. Radiohalos (spheres of radiation damage in minerals surrounding radioactive (α-emitting) inclusions) provide useful analogues for studying long term α-particle damage accumulation. In this study, silicate minerals adjacent to Th- and U-rich monazite and zircon were probed for redox changes and long/short range disorder using microfocus X-ray absorption spectroscopy (XAS) and high resolution X-ray diffraction (XRD) at Beamline I18, Diamond Light Source. Fe3+ → Fe2+ reduction has been demonstrated in an amphibole sample containing structural OH– groups – a trend not observed in anhydrous phases such as garnet. Coincident with the findings of Pattrick et al. (2013), the radiolytic breakdown of OH– groups is postulated to liberate Fe3+ reducing electrons. Across all samples, high point defect densities and minor lattice aberrations are apparent adjacent to the radioactive inclusion, demonstrated by micro-XRD.

Behavior of UO2 in the RBMK-1000 Spent Fuel under Oxidizing Conditions

2004 ◽  
Vol 824 ◽  
Author(s):  
A. B. Kolyadin ◽  
V. Ya. Mishin ◽  
K. Ya. Mishin ◽  
A. S. Aloy ◽  
T. I. Koltsova
Keyword(s):  
Thermal Oxidation ◽  
Spent Nuclear Fuel ◽  
Oxidation Process ◽  
Spent Fuel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dry Storage ◽  
Different Temperatures ◽  
Xrd Techniques

AbstractThe oxidation of UO2–type spent nuclear fuel (SNF) in gaseousmedia was studied at different temperatures and oxygen contents using gravimetric and powder X-ray diffraction (XRD) techniques. The aim of the study was to determine the mechanism(s) of thermal-oxidation alteration of SNF during long-term dry storage. The samples used in the experiments were chips of RBMK-1000 fuel rods.Oxidation of UO2with a mean burn-up of 10.7 and 19.73 MW d/kg in humid air was observed at a temperature as low as 150°C. At 200°C nearly all of the UO2was transformed into U3O8 between 3500-4000 hours. In a humid nitrogen environment containing of 0.05-1.3 vol. % oxygen at 300°C, the UO2 completely transformed to U3O8 between 2500-3000 hours. Oxidation of UO2in samples with small amounts of jacket damage (e.g., <0.04 MM2)ll progresses more slowly and after â3000 hours the oxygen-to-uranium ratio was 2.56.Stabilization of the oxidation process was not observed in the fuel samples upto an O/U ratio of 2.4, which may be attributed to the smallburn-up of the fuel under investigation.

Characterization of selenium in UO2spent nuclear fuel by micro X-ray absorption spectroscopy and its thermodynamic stability

2015 ◽  
Vol 17 (10) ◽  
pp. 1760-1768 ◽  
Author(s):  
E. Curti ◽  
A. Puranen ◽  
D. Grolimund ◽  
D. Jädernas ◽  
D. Sheptyakov ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Fission Product ◽  
Nuclear Fuel ◽  
Absorption Spectroscopy ◽  
Thermodynamic Stability ◽  
Spent Nuclear Fuel ◽  
X Ray ◽  
Geological Repository ◽  
X Ray Absorption

The long-lived fission product79Se is tightly bound to the UO2lattice in spent nuclear fuel; it will thus be released only very slowly from a geological repository for radioactive waste.

scholarly journals Characterising legacy spent nuclear fuel pond materials using microfocus X-ray absorption spectroscopy

2016 ◽  
Vol 317 ◽  
pp. 97-107 ◽  
Author(s):  
W.R. Bower ◽  
K. Morris ◽  
J.F.W. Mosselmans ◽  
O.R. Thompson ◽  
A.W. Banford ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Absorption Spectroscopy ◽  
Spent Nuclear Fuel ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Water corrosion of spent nuclear fuel: radiolysis driven dissolution at the UO2/water interface

2015 ◽  
Vol 180 ◽  
pp. 301-311 ◽  
Author(s):  
Ross Springell ◽  
Sophie Rennie ◽  
Leila Costelle ◽  
James Darnbrough ◽  
Camilla Stitt ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Complex Surface ◽  
Water Interface ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray ◽  
Radiation Fields ◽  
Long Term Storage ◽  
Rate Of Dissolution

X-ray diffraction has been used to probe the radiolytic corrosion of uranium dioxide. Single crystal thin films of UO2 were exposed to an intense X-ray beam at a synchrotron source in the presence of water, in order to simultaneously provide radiation fields required to split the water into highly oxidising radiolytic products, and to probe the crystal structure and composition of the UO2 layer, and the morphology of the UO2/water interface. By modeling the electron density, surface roughness and layer thickness, we have been able to reproduce the observed reflectivity and diffraction profiles and detect changes in oxide composition and rate of dissolution at the Ångström level, over a timescale of several minutes. A finite element calculation of the highly oxidising hydrogen peroxide product suggests that a more complex surface interaction than simple reaction with H2O2 is responsible for an enhancement in the corrosion rate directly at the interface of water and UO2, and this may impact on models of long-term storage of spent nuclear fuel.

Corrosion of commercial spent nuclear fuel. 2. Radiochemical analyses of metastudtite and leachates

2005 ◽  
Vol 93 (3) ◽  
Author(s):  
Bruce McNamara ◽  
Brady D. Hanson ◽  
Edgar C. Buck ◽  
Chuck Soderquist
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Deionized Water ◽  
Corrosion Products ◽  
Contact Period ◽  
Water Interface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Air Water Interface

SummaryImmersing commercial spent nuclear fuel (CSNF) in deionized water produced two corrosion products after a 2-year contact period. Suspensions of aggregates were observed to form at the air–water interface for each of five samples. These suspended aggregates were characterized by X-ray diffraction (XRD) to be metastudtite (UO

Trace Element Chemistry in Spent Nuclear Fuel Using X-ray Absorption Spectroscopy

2004 ◽  
Vol 10 (S02) ◽  
pp. 824-825
Author(s):  
Jeffrey A. Fortner ◽  
A. Jeremy Kropf ◽  
Robert J. Finch ◽  
James C. Cunnane
Keyword(s):  
Trace Element ◽  
Nuclear Fuel ◽  
Absorption Spectroscopy ◽  
Spent Nuclear Fuel ◽  
X Ray ◽  
Trace Element Chemistry ◽  
Element Chemistry ◽  
X Ray Absorption

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

scholarly journals Tc and Re Behavior in Borosilicate Waste Glass Vapor Hydration Tests

2006 ◽  
Vol 985 ◽  
Author(s):  
David A. McKeown ◽  
Andrew C. Buechele ◽  
Wayne W. Lukens ◽  
David K. Shuh ◽  
Ian L. Pegg
Keyword(s):  
High Mobility ◽  
Sample Surface ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Long Term Storage ◽  
Before And After ◽  
X Ray Absorption ◽  
Term Storage ◽  
Scanning Electron

AbstractTechnetium (Tc), found in some nuclear wastes, is of particular concern with regard to long-term storage, because of its long-lived radioactivity and high mobility in the environment. Tc and rhenium (Re), commonly used as a non-radioactive surrogate for Tc, were studied to assess their behavior in borosilicate glass under hydrothermal conditions in the Vapor Hydration Test (VHT). X-ray absorption spectroscopy (XAS) and scanning electron microscopy (SEM) measurements were made on the original Tc- and Re-containing glasses and their corresponding VHT samples, and show different behavior for Tc and Re under VHT conditions. XAS indicates that, despite starting with different Tc(IV) and Tc(VII) distributions in each glass, the VHT samples have 100% Tc(IV)O6 environments. SEM shows complete alteration of the original glass, Tc enrichment near the sample surface, and Tc depletion in the center. Perrhenate (Re(VII)O4−) is dominant in both Re-containing samples before and after the VHT, where Re is depleted near the VHT sample surface and more concentrated toward the center.

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