NMR Investigation of Cation Distribution in HLW Wasteform Glass

2008 ◽  
Vol 1107 ◽  
Author(s):  
Diane Holland ◽  
Ben G Parkinson ◽  
Moinul M Islam ◽  
Adam Duddridge ◽  
Jonathan M Roderick ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Aqueous Corrosion ◽  
Alkali Cations ◽  
Chemical Behaviour ◽  
High Level Nuclear Waste ◽  
Angle Spinning ◽  
High Level ◽  
Physical And Chemical

AbstractMagic-angle-spinning NMR has been used to establish the structural roles of various cations added to the borosilicate glass which is used for the vitrification of high-level nuclear waste (HLW). Representative surrogate oxides with nominal valencies of +1, +2 and +3 have been studied which span the range of oxides from modifier to intermediate and conditional glassformer. NMR has been carried out on those nuclei which are accessible and the species observed have been correlated with the physical and chemical behaviour. The controlling factor is the manner in which the alkali cations partition between the various network groups, changing the distribution of silicon Qn species and the boron N4 ratio. Identifiable superstructural units are also present in these glasses. The aqueous corrosion rate increases with Q3 content, as does the weight loss due to evaporation from the melt. The activation energy for DC conduction scales with N4. Values of N4 obtained for these glasses deviate significantly from those predicted by the currently accepted model (Dell and Bray) and are strongly affected by the modifier or intermediate nature of the surrogate oxide and also by its effect on the distribution of nonbridging oxygens between the silicate and borate polyhedra.

Chemical Durability Studies of Waste-Simulant Doped Borosilicate Glasses

2003 ◽  
Vol 807 ◽  
Author(s):  
Adam Duddridge ◽  
Moinul Islam ◽  
Diane Holland ◽  
Charlie R. Scales
Keyword(s):  
Test Procedure ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Borosilicate Glasses ◽  
Nmr Studies ◽  
Mixed Alkali ◽  
Trivalent Cations ◽  
High Level Nuclear Waste ◽  
Angle Spinning ◽  
High Level

ABSTRACTA mixed-alkali modified borosilicate base glass used in the vitrification of high-level nuclear waste (HLW) has been doped with a number of waste simulants to between 2 and 12 mol%. The simulants have been chosen to give two distinct series of glasses: one consisting of trivalent ions having the form M2O3(where M is La, Bi, Al or Fe) and the other consisting of divalent simulants of the form MO (where M is Pb, Zn or Ba). An international standard Soxhlet leach test procedure was performed on each glass to study the effect of prolonged, moderate-temperature, dynamic water corrosion. Results of these studies show that, except for BaO, as the amount of simulant is increased, the amount of Na and Li leached decreases showing them to become more chemically resistant. These corrosion tests have been correlated to ionic (D.C.) conductivity measurements, which show a decrease in the conductivity of the glass as the amount of waste simulant is increased, and 11B magic-angle spinning nuclear magnetic resonance (MAS-NMR) studies, which have shown that, as more waste-simulant is loaded into the glasses the rate of conversion of [BO4] to [BO3] units increases. All of the data from these studies reflect the different network forming abilities of the divalent and trivalent cations.

Comparative Structural Study and Dissolution of Simplified Glasses: A Radioactive Waste Glass (R7T7) and a Basaltic Glass

1997 ◽  
Vol 506 ◽  
Author(s):  
F. Angeli ◽  
P. Faucon ◽  
T. Charpentier ◽  
J.C. Petit ◽  
J. Virlet
Keyword(s):  
Nuclear Waste ◽  
Magic Angle Spinning ◽  
Waste Glass ◽  
Magic Angle ◽  
Basaltic Glass ◽  
Qualitative Information ◽  
Local Environments ◽  
Nuclear Waste Glass ◽  
Angle Spinning ◽  
Main Components

ABSTRACTThe local cation environments in a borosilicate glass (containing the main components of the French nuclear waste glass, R7T7) and of basaltic-like glass are presented on the basis of17A1 and23Na Multi-Quanta Magic-Angle Spinning Nuclear Magnetic Resonance (MQ-MAS NMR) spectroscopies. The chemical and geometrical environment of each nucleus is characterized. Moreover, qualitative information about the distribution of these parameters, characteristic of the disorder level in the structure, is obtained. These results are presented with the characteristics of the Al and Na dissolution in water at 100°C. The relation between the local environments of these cations and their mass loss in solution is discussed.

Methodologies for Predicting the Performance of Ni-Cr-Mo Alloys Proposed for High Level Nuclear Waste Containers

1999 ◽  
Vol 556 ◽  
Author(s):  
D. S. Dunn ◽  
G. A. Cragnolino ◽  
N. Sridhar
Keyword(s):  
Nuclear Waste ◽  
Current Density ◽  
Localized Corrosion ◽  
Passive Current Density ◽  
Aqueous Corrosion ◽  
Wide Range ◽  
Anionic Species ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Passive Current

AbstractFor the geologic disposal of the high level nuclear waste (HLW), aqueous corrosion is considered to be the most important factor in the long-term performance of containers, which are the main components of the engineered barrier subsystem. Container life, in turn, is important to the overall performance of the repository system. The proposed container designs and materials have evolved to include multiple barriers and highly corrosion resistant Ni-Cr-Mo alloys, such as Alloys 625 and C-22. Calculations of container life require knowledge of the initiation time and growth rate of localized corrosion. In the absence of localized corrosion, the rate of general or uniform dissolution, given by the passive current density of these materials, is needed. The onset of localized corrosion may be predicted by using the repassivation and corrosion potentials of the candidate container materials in the range of expected repository environments. In initial corrosion tests, chloride was identified as the most detrimental anionic species to the performance of Ni-Cr-Mo alloys. Repassivation potential measurements for Alloys 825, 625, and C-22, conducted over a wide range of chloride concentrations and temperatures, are reported. In addition, steady state passive current density, which will determine the container lifetime in the absence of localized corrosion, was measured for Alloy C-22 under various environmental conditions.

scholarly journals 14N, 13C, and 119Sn solid-state NMR characterization of tin(II) carbodiimide Sn(NCN)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Aleksander Jaworski ◽  
Jędrzej Piątek ◽  
Liuda Mereacre ◽  
Cordula Braun ◽  
Adam Slabon
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Quadrupolar Coupling ◽  
Nmr Study ◽  
Nmr Characterization ◽  
Angle Spinning ◽  
High Level

Abstract We report the first magic-angle spinning (MAS) nuclear magnetic resonance (NMR) study on Sn(NCN). In this compound the spatially elongated (NCN)2− ion is assumed to develop two distinct forms: either cyanamide (N≡C–N2−) or carbodiimide (−N=C=N−). Our 14N MAS NMR results reveal that in Sn(NCN) the (NCN)2− groups exist exclusively in the form of symmetric carbodiimide ions with two equivalent nitrogen sites, which is in agreement with the X-ray diffraction data. The 14N quadrupolar coupling constant | C Q | $\vert {C}_{\text{Q}}\vert $  ≈ 1.1 MHz for the −N=C=N− ion in Sn(NCN) is low when compared to those observed in molecular compounds that comprise cyano-type N≡C– moieties ( | C Q | $\vert {C}_{\text{Q}}\vert $  > 3.5 MHz). This together with the information from 14N and 13C chemical shifts indicates that solid-state NMR is a powerful tool for providing atomic-level insights into anion species present in these compounds. The experimental NMR results are corroborated by high-level calculations with quantum chemistry methods.

A Possibility for Hlw Disposal in Very Deep Boreholes

1991 ◽  
Vol 257 ◽  
Author(s):  
A.V. Byalko
Keyword(s):  
Melting Temperature ◽  
Nuclear Waste ◽  
Waste Disposal ◽  
Chemical Processes ◽  
Ecological Safety ◽  
High Level Nuclear Waste ◽  
Deep Boreholes ◽  
High Level ◽  
Physical And Chemical ◽  
The Given

ABSTRACTRecently we proposed [1] that high-level nuclear waste be deposited in very deep boreholes, filled with a substance of low melting temperature, of high density, not generating gases and water-insoluble.The first paper outlined nuclear waste disposal in deep boreholes, discussions of physical and chemical processes in a filled borehole and preliminarily comments on the ecological safety of the disposal. The given paper covers some economical aspects of the new proposal as well as the principal steps of implementation of the R&D program.

Er3+ Doped Silica Glass by Sol-Gel Processing with Organic Complexation

1999 ◽  
Vol 560 ◽  
Author(s):  
Xiuhong Han ◽  
Guozhong Cao ◽  
Tom Pratum
Keyword(s):  
Silica Glass ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Complexing Agent ◽  
Magic Angle ◽  
Silica Network ◽  
Organic Complexation ◽  
Angle Spinning ◽  
High Level ◽  
Gel Processing

ABSTRACTEr3+-doped silica glass (up to 10 wt%) was synthesized by sol-gel processing with the addition of 3- aminopropyl trimethoxysilane (APS) as a complexing agent. Er3+ ions reacted with amino groups and, thus, linked to the silica network during the sol preparation. As a result, the motion of Er3+ ions was restricted and the formation of Er3+ clusters was inhibited. Both fluorescence spectra and magic-angle spinning (MAS) nuclear magnetic resonance (NMR) indicated that the addition of the complexing agent APS resulted in a homogeneous dispersion of high-level Er+3 doping in the resultant gels. After the removal of organic components, however, Er+3 clustering occurs when firing at a high temperature for a long period of time, e.g. at 1000°C for 10 hrs, due to enhanced Er3+ diffusion.

Powder diffraction of sodalite in a multiphase ceramic used to immobilize radioactive waste

2005 ◽  
Vol 20 (3) ◽  
pp. 212-214 ◽  
Author(s):  
S. M. Frank ◽  
T. L. Barber ◽  
M. J. Lambregts
Keyword(s):  
Radioactive Waste ◽  
Powder Diffraction ◽  
Lattice Parameter ◽  
Magic Angle Spinning ◽  
High Level Waste ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
X Ray ◽  
Angle Spinning ◽  
High Level

The title compound, ∣Na6Li1.6K0.4Cl2∣[Al6Si6O24]‐SOD, is similar to sodalite proper, but the introduction of Li and K into the structure creates a reduction in unit-cell volume and additional collapse of the framework tetrahedra. Refinement of an X-ray powder diffraction pattern of a multiphase material yielded for sodalite a lattice parameter of 0.88427 (2) nm, an Al–O–Si bond angle of 137.9(3°), and Al–O and Si–O bond lengths of 0.1730(5) nm and 0.1620(5) nm, respectively. The angle of the unique Al–O–Si bond corresponds well with the 138° obtained by 29Si solid-state magic-angle-spinning nuclear magnetic resonance spectroscopy. This characterization is important since the compound constitutes an essential part of a radioactive waste form intended for a high-level waste repository.

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

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