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Melter Feed Reactions at T ≤ 700°C for Nuclear Waste Vitrification
Author(s) -
Xu Kai,
Hrma Pavel,
Rice Jarrett,
Riley Brian J.,
Schweiger Michael J.,
Crum Jarrod V.
Publication year - 2015
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.13766
Subject(s) - vitrification , gibbsite , boron , amorphous solid , boron oxide , materials science , leaching (pedology) , borosilicate glass , oxide , radioactive waste , scanning electron microscope , chemical engineering , nuclear chemistry , inorganic chemistry , chemistry , metallurgy , aluminium , crystallography , medicine , environmental science , organic chemistry , soil science , engineering , composite material , andrology , soil water
To understand feed‐to‐glass conversion for the vitrification of nuclear waste, we investigated batch reactions and phase transitions in a simulated nuclear waste glass melter feed heated at 5 K/min up to 700°C using optical microscopy, scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, and X‐ray diffraction. To determine the content and composition of leachable phases, we performed leaching tests; the leachates were analyzed by inductively coupled plasma atomic emission spectroscopy. By 400°C, gibbsite and sodium borates lost water and converted to amorphous phase, whereas other metallic hydroxides dehydrated to oxides. Between 400°C and 700°C, carbonates decomposed before 500°C; amorphous aluminum oxide and calcium oxide reacted with the sodium borate and formed the more durable amorphous borate phase along with intermediate crystalline products; above 500°C, quartz began to dissolve, and hematite started to convert to trevorite.