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Titanate Ceramics for the Stabilization of Partially Reprocessed Nuclear Fuel Elements
Author(s) -
Ball Clifford J.,
Buykx William J.,
Dickson Fiona J.,
Hawkins Kate,
Levins Desmond M.,
Smart Roger St. C.,
Smith Katherine L.,
Stevens Geoffry T.,
Watson Kenneth G.,
Weedon David,
White Timothy J.
Publication year - 1989
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.1151-2916.1989.tb06144.x
Subject(s) - uranium , dissolution , brookite , materials science , ceramic , hollandite , uraninite , rutile , distilled water , titanate , titanium , mineralogy , solubility , nuclear chemistry , analytical chemistry (journal) , chemical engineering , metallurgy , chemistry , anatase , biochemistry , organic chemistry , chromatography , photocatalysis , engineering , catalysis
A titanate ceramic designed to immobilize high‐level waste generated by Amine reprocessing of heavy‐water reactor fuel and fabricated by uniaxial hot‐pressing was characterized. X‐ray diffraction and selected‐area electron diffraction were used to identify a six‐phase assemblage consisting of betafite, a hollandite structure type, perovskite, uraninite, hibonite, and Magnéli phases. Secondary electron imaging of polished surfaces revealed many microvoids consistent with a measured density of 5.25 g · cm −2 (∼90% of theoretical density). The waste form was chemically heterogeneous at the hundreds of micrometers scale, as backscattered electron imaging and energy‐dispersive X‐ray spectroscopy indicated that regions rich in either uranium or titanium oxides were common. Grain sizes ranged from 0.1 to 0.5 μm. All crystals were faceted with the exception of anhedral uraninite grains. Dissolution experiments conducted at 90°C in distilled water gave uranium and titanium loss rates which were solubility limited (10 −1 to 10 −4 g · m −2 · d −1 ), while cesium dissolution, which was not contrained by solubility limits, was more rapid (23.3 g · m −2 · d −1 ). Hydrothermal testing at 150°C in distilled water resulted in precipitation of uranium(VI) titanate (UTiO 5 ) and brookite (TiO 2 ).