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Processing Impurities as Phase Assemblage Modifiers in Titanate Nuclear Waste Ceramics
Author(s) -
Buykx William J.,
Levins Desmond M.,
Smart Roger St. C.,
Smith Katherine L.,
Stevens Geoffrey T.,
Watson Kenneth G.,
White Timothy J.
Publication year - 1990
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/j.1151-2916.1990.tb06496.x
Subject(s) - purex , impurity , dissolution , radioactive waste , materials science , titanate , ceramic , phase (matter) , actinide , nuclear chemistry , scanning electron microscope , chemical engineering , mineralogy , metallurgy , chemistry , composite material , chromatography , organic chemistry , engineering , extraction (chemistry) , solvent extraction
The tolerance of titanate nuclear waste ceramics to fluctuations in the concentrations of processing contaminants was monitored using X‐ray diffraction, electron microscopy, secondary ion mass spectrometry, and analysis of dissolution liquors. Several waste forms were fabricated, all of which contained idealized Purex waste simulant and, in addition, varying quantities of the common waste stream impurities P 2 O 5 , MgO, Fe 2 O 3 , Na 2 O, and SiO 2 . Incorporation of the oxides individually stabilized new phases including monazite (P 2 O 5 ), pseudobrookite (MgO), loveringite (Fe 2 O 3 ), freudenbergite (Na 2 O), and pollucite (SiO 2 )—only the latter phase deleteriously affected waste form performance by promoting cesium dissolution. However, when the processing contaminants were added simultaneously, a number of synergetic effects, particularly the stabilization of a soluble glassy phase, resulted in elemental losses which were an order of magnitude greater for some matrix and radwaste species. It was found that up to 25 wt% of the idealized Purex waste could be incorporated in the waste without diminution of its properties.