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Crystallization study of rare earth and molybdenum containing nuclear waste glass ceramics
Author(s) -
McCloy John S.,
Riley Brian J.,
Crum Jarrod,
Marcial José,
Reiser Joelle T.,
Kruska Karen,
Peterson Jacob A.,
Neuville Daniel R.,
Patil Deepak S.,
Saleh Muad,
Barnsley Kristian E.,
Hanna John V.
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16406
Subject(s) - materials science , borosilicate glass , crystallization , analytical chemistry (journal) , alkali metal , nuclear fission product , mineralogy , fission products , chemical engineering , metallurgy , chemistry , radiochemistry , organic chemistry , chromatography , engineering
A glass‐ceramic waste form is being developed for immobilization of waste streams of alkali (A), alkaline‐earth (AE), rare earth (RE), and transition metals generated by transuranic extraction for reprocessing of used nuclear fuel. Benefits over an alkali borosilicate waste form are realized by the partitioning of the fission product fraction insoluble in glass into a suite of chemically durable crystalline phases through controlled cooling, including (AE,A,RE)MoO 4 (powellite) and (RE,A,AE) 10 Si 6 O 26 (oxyapatite). In this study, a simplified 8‐oxide system (SiO 2 ‐Nd 2 O 3 ‐CaO‐Na 2 O‐B 2 O 3 ‐Al 2 O 3 ‐MoO 3 ‐ZrO 2 ) was melted, then soaked at various temperatures from 1450 to 1150°C, and subsequently quenched, in order to obtain snapshots into the phase distribution at these temperatures. For these samples, small angle X‐ray and neutron scattering, quantitative X‐ray diffraction, electron microscopy, 23 Na nuclear magnetic resonance, Nd 3+ visible absorption, and temperature‐dependent viscosity were characterized. In this composition, soak temperatures of ≲ 1250°C were necessary to nucleate calcium molybdate (~10‐20 nm in diameter). Further cooling produced oxyapatite and total crystallization increased with lower soak temperatures. Both Na and Nd entered the crystalline phases with lower‐temperature soak conditions. Slow cooling or long isothermal treatments at ~975°C produced significantly higher crystal fractions.