Plutonium and Neptunium Incorporation in Zirconolite

1996 ◽  
Vol 465 ◽  
Author(s):  
B. D. Begg ◽  
E. R. Vance ◽  
R.A Day ◽  
M. Hambley ◽  
S. D. Conradson
Keyword(s):  
Absorption Spectroscopy ◽  
Valence State ◽  
Charge Compensation ◽  
Redox Conditions ◽  
X Ray ◽  
Compensation Mechanisms ◽  
X Ray Absorption

ABSTRACTThe incorporation of Pu and Np in zirconolite (CaZrTi2O7) has been investigated over a range of redox conditions. Zirconolite formulations designed to favour either trivalent or tetravalent Pu and Np were prepared by limiting the amount of charge compensating additives available to maintain electroneutrality. From near-edge X-ray absorption spectroscopy the Pu valence state was found to vary with the processing atmosphere, from completely tetravalent when fired in air, and located on either the Ca or Zr sites, to trivalent, when substituted on the Ca site after annealing in 3.5% H2/N2. Np was predominantly tetravalent over the range of redox conditions examined and was readily incorporated on either of zirconolite's Ca or Zr sites. The charge compensation mechanisms at work in different zirconolites are also discussed.

Charge compensation mechanisms in U 1-x Gd x O 2 and Th 1-x Gd x O 2-x/2 studied by X-ray Absorption Spectroscopy

2017 ◽  
Vol 489 ◽  
pp. 9-21 ◽  
Author(s):  
R. Bès ◽  
J. Pakarinen ◽  
A. Baena ◽  
S. Conradson ◽  
M. Verwerft ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Charge Compensation ◽  
X Ray ◽  
Compensation Mechanisms ◽  
X Ray Absorption ◽  
Th 1

The Incorporation of Cerium in Zirconolite

1996 ◽  
Vol 465 ◽  
Author(s):  
B. D. Begg ◽  
E. R. Vance
Keyword(s):  
Absorption Spectroscopy ◽  
Nuclear Waste ◽  
Valence State ◽  
Charge Compensation ◽  
Sample Design ◽  
Sintering Atmosphere ◽  
X Ray ◽  
High Level Nuclear Waste ◽  
High Level ◽  
X Ray Absorption

ABSTRACTZirconolite (CaZrTi2O7) is the primary actinide-bearing Synroc phase for the immobilisation of high-level nuclear waste. Using X-ray absorption spectroscopy and microanalysis we have investigated the incorporation of cerium, as a simulant for plutonium, on both zirconolite's Ca and Zr sites under a range of redox conditions. The Ce valence state was found to vary between Ce3+ and Ce4+ depending on the both the sintering atmosphere and temperature. The existence of alternative charge compensation schemes, predominantly cation vacancies, in addition to those used in the sample design was inferred in many of the zirconolites and will be discussed in detail.

Charge compensation and capacity fading in LiCoO 2 at high voltage investigated by soft x-ray absorption spectroscopy

2018 ◽  
Vol 27 (10) ◽  
pp. 107802 ◽  
Author(s):  
Xing-Hui Long ◽  
Yan-Ru Wu ◽  
Nian Zhang ◽  
Peng-Fei Yu ◽  
Xue-Fei Feng ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
High Voltage ◽  
Charge Compensation ◽  
Capacity Fading ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Valence state fossils in Proterozoic stromatolites by L-edge X-ray absorption spectroscopy

2007 ◽  
Vol 112 (G3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Stephen J. Brotton ◽  
Russell Shapiro ◽  
Gerrit van der Laan ◽  
Jinghua Guo ◽  
Per-Anders Glans ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Valence State ◽  
X Ray ◽  
X Ray Absorption

In situ X-ray Absorption Spectroscopy Characterization of Copper Valence State in Cu-Zn/SiO2 Catalyst

2018 ◽  
Vol 76 (8) ◽  
pp. 639
Author(s):  
Zhenlong Jia ◽  
Yunbao Tu ◽  
Jianqiang Wang ◽  
Anatoly I. Frenkel ◽  
Weimin Yang ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Valence State ◽  
X Ray ◽  
Copper Valence ◽  
X Ray Absorption

Synroc Derivatives for the Hanford Waste Remediation Task

1996 ◽  
Vol 465 ◽  
Author(s):  
E. R. Vance ◽  
K. P. Hart ◽  
R. A. Day ◽  
M. L. Carter ◽  
M. Hambley ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Hot Pressing ◽  
Metal Alloy ◽  
Redox Conditions ◽  
Short Term ◽  
X Ray ◽  
Glass Composites ◽  
Additive Schemes ◽  
Waste Remediation ◽  
X Ray Absorption

ABSTRACTThree wt% each of Cs and Tc were mixed with the standard Synroc precursor and the ceramic was formed by hot-pressing. Attempts were made to incorporate the Tc as either metal or Tc 4+, using different redox conditions in processing. Volatile losses of Tc during calcination were < 0.1% in all cases. Short-term Tc leach rates when the Tc was present as a metal alloy were in the order of 10−4 g/m /d at 90°C with frequently changed water, and decreased with increasing leaching time. The valence of the Tc was monitored by X-ray absorption spectroscopy at the drying and calcination stages of the production. The general viability of Synroc/glass composites for immobilising the Hanford HLW sludges is further demonstrated by using further refinements of additive schemes for the inactive “All-blend” formulation and initial studies using the U-containing “All-blend” waste formulation.

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