Stability of I and SR Radiophases in Cement Matrices

1981 ◽  
Vol 6 ◽  
Author(s):  
M.W. Barnes ◽  
B.E. Scheetz ◽  
L.D. Wakeley ◽  
S.D. Atkinson ◽  
D.M. Roy
Keyword(s):  
Nuclear Waste ◽  
Complete Understanding ◽  
Waste Forms ◽  
Diffusion Controlled ◽  
The Stability ◽  
And Diffusion ◽  
Nuclear Waste Forms ◽  
Aluminate Cement ◽  
Short Times ◽  
Curing Cement

ABSTRACTThe following study is a portion of a comprehensive research program that is examining the stability of a variety of nuclear waste forms. In addition to the bulk waste forms, important individual radiophases are being studied to obtain a more complete understanding of the behavior of the components of complex multiphase radwaste systems. The stability of the strontium radiophase in supercalcine and an iodine-radiophase will be discussed.The strontium radiophase in this study was Sr-powellite and the iodine radiophase was I-sodalite. Each radiophase was incorporated into bulk compositionally adjusted portland and aluminate cements. Two processing variables were studied: curing at 60°C and warm pressing at 150°C and 345 MPa.Sr-powellite in portland cement leaches incongruently; a combination of dissolution and diffusion-controlled exchange of Ca for Sr is demonstrated. In the warm-pressed aluminate cement these reactions are masked by reactions with the curing cement. I-sodalite leaching data indicate dissolution, dominant at long times, combined with diffusion, dominant at short times.

scholarly journals Understanding the Stability of Salt-Inclusion Phases for Nuclear Waste-forms through Volume-based Thermodynamics

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Emily E. Moore ◽  
Vancho Kocevski ◽  
Christian A. Juillerat ◽  
Gregory Morrison ◽  
Mingyang Zhao ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Waste Forms ◽  
The Stability ◽  
Nuclear Waste Forms

Dissolution of Technetium From Nuclear Waste Forms

1983 ◽  
Vol 26 ◽  
Author(s):  
M. Yasser Khalil ◽  
William B. White
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Stability Field ◽  
Glass Waste ◽  
Waste Forms ◽  
Reducing Conditions ◽  
Valence States ◽  
The Stability ◽  
Nuclear Waste Forms ◽  
Similar Kinetic

ABSTRACTThe immobilization of 99Tc in both ceramic and borosilicate glass waste forms and the mechanism of dissolution of technetium from these waste forms are complicated by the range of technetium valence states. Metallic Tc,ionic Tc4+ oxides, and volatile molecular species containing Tc7+ all occur within the stability field of water. Tc4+ will substitute readily for Ti4+ in titanatebased ceramics in such phases as perovskite (CaTiO3) and spinel (Mg2TiO4). Tc4+ can be homogeneously distributed in borosilicate glass by re-melting the glass under closed system conditions to prevent the re-oxidation of technetium. The dissolution of technetium from both glass and ceramic waste forms follow similar kinetic behavior although the dissolution rate from the titanate is two orders of magnitude lower. Dissolution under highly reducing conditions is too slow to measure on the time scale of the experiments.

scholarly journals Ab Initio Investigation of Helium Mobility in La2Zr2O7 Pyrochlore

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 667
Author(s):  
Yanxia Lu ◽  
Qing Peng ◽  
Chenguang Liu
Keyword(s):  
Nuclear Waste ◽  
Density Functional ◽  
Minimum Energy ◽  
Elastic Band ◽  
Waste Forms ◽  
Band Method ◽  
And Migration ◽  
High Level ◽  
Migration Pathways ◽  
Nuclear Waste Forms

The α-decay of incorporated actinides continuously produces helium, resulting in helium accumulation and causing security concerns for nuclear waste forms. The helium mobility is a key issue affecting the accumulation and kinetics of helium. The energy barriers and migration pathways of helium in a potential high-level nuclear waste forms, La2Zr2O7 pyrochlore, have been investigated in this work using the climbing image nudged elastic band method with density functional theory. The minimum energy pathway for helium to migrate in La2Zr2O7 is identified as via La–La interstitial sites with a barrier of 0.46 eV. This work may offer a theoretical foundation for further prospective studies of nuclear waste forms.

Using “radioparagenesis” to design robust nuclear waste forms

2010 ◽  
Vol 3 (1) ◽  
pp. 130-135 ◽  
Author(s):  
C. Jiang ◽  
B. P. Uberuaga ◽  
K. E. Sickafus ◽  
F. M. Nortier ◽  
J. J. Kitten ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Waste Forms ◽  
Nuclear Waste Forms

MCC-1: A Standard Leach Test for Nuclear Waste Forms

1982 ◽  
Vol 56 (2) ◽  
pp. 306-312 ◽  
Author(s):  
D.M. Strachan ◽  
R. P. Turcotte ◽  
B. O. Barnes
Keyword(s):  
Nuclear Waste ◽  
Waste Forms ◽  
Leach Test ◽  
Nuclear Waste Forms

Hydrothermal Reactivity of Simulated Nuclear Waste Forms and Water-Catalysed Waste-Rock Interactions

1979 ◽  
pp. 329-340 ◽  
Author(s):  
G. J. McCarthy ◽  
Sridhar Komarneni ◽  
Barry E. Scheetz ◽  
William B. White
Keyword(s):  
Nuclear Waste ◽  
Waste Rock ◽  
Waste Forms ◽  
Nuclear Waste Forms

Leaching of nuclear waste forms

Nature ◽  
1983 ◽  
Vol 302 (5910) ◽  
pp. 727-727
Author(s):  
A. E. RINGWOOD
Keyword(s):  
Nuclear Waste ◽  
Waste Forms ◽  
Nuclear Waste Forms
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