DEVELOPMENT OF GLASS COMPOSITIONS TO IMMOBILIZE ALKALI, ALKALINE EARTH, LANTHANIDE AND TRANSITION METAL FISSION PRODUCTS FROM NUCLEAR FUEL REPROCESSING Page: 4 of 9
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The testing was conducted in a serial manner where several glass formulations were developed in
phases building off of results from the previous phase and incorporation of changes in waste
compositions to reflect new knowledge gained from separations flowsheet development and testing.
For brevity and illustration purposes, only one or two glass compositions will be discussed for each
waste immobilization option.
The waste composition of the Ln-only stream is projected to consist of a majority of the
lanthanides from the lanthanide series as oxides (Ln203). The major lanthanide oxides expected to be
present are Ce203, La203, Nd203 and Pr203. Combining the TM stream with the Ln stream adds noble
metal fission products (primarily RuO2, Rh203 and PdO) to the combined stream. It is expected that a
significant amount of ZrO2 will also be introduced to the combined Ln/TM stream by the introduction
of the TM stream.
When the Cs/Sr waste stream is added to Ln/TM combined stream, the main constituents added
are Cs2O, SrO, BaG and MoO3. The addition of the Cs/Sr stream increases the relative heat load of the
waste significantly. Depending on variations in potential flowsheets, the efficiency of the separations
processes and the relative partitioning of elements in the waste streams, the combined Cs/Sr/Ln/TM
stream was represented by two extremes. One extreme consisted of high MoO3 content while the other
extreme had high noble metal contents. Both MoO3 and noble metals can have significant impacts on
waste loading. It is expected the waste stream compositions will become more definitive as the
separations processes mature and are tested. However, at this stage testing extreme levels appeared to
be a prudent approach.
Identification of Candidate Glass Forming Systems
Option 1- A lanthanide borosilicate (LaBS) glass was identified as a suitable candidate for
immobilization of the lanthanide waste stream, because the waste stream consists mainly of rare earth
Option 2- An alkali borosilicate glass was identified as a suitable candidate for the
immobilization of the combined Ln and TM waste stream, because of the complex chemical makeup of
Option 3 - Alkali borosilicate glass systems were identified as likely candidates for
immobilization of the combined Cs/Sr/Ln/TM waste stream, because of the complex chemical makeup
of the waste and high variability of MoO3, noble metals, and ZrO2.
Each test matrix glass was prepared from the proper proportions of reagent-grade metal oxides,
carbonates, H3B03, and salts to produce sufficient glass for the associated testing (typically 200
grams). In general, the raw materials were thoroughly mixed and placed into platinum-alloy crucibles
(Pt, Pt/Rh, or Pt/Au). In the case of glasses containing high levels of noble metal oxides (RuO2,
Rh203, PdO, Ag2O, etc.), the batch materials were melted in alumina or silica crucibles in order to
prevent undesired reactions with the glass and platinum-alloy crucibles during melting. The well
mixed batches were placed into electrically heated, high-temperature furnaces at melting temperatures
between 1250 C and 1400 C. After an isothermal hold at the targeted melting temperature for
nominally 2 hours, the crucibles were removed from the furnaces, and the glasses were poured onto a
clean stainless steel plate and allowed to air cool (quenched). In some cases the glass was removed
from the furnace and allowed to air cool while remaining in the crucible. The glass pour patties were
used as the sampling stock for the various property measurements (e.g. product consistency test [PCT],
liquidus temperature [TL], X-ray diffraction [XRD] and chemical composition).
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Marra, J. & Billings, A. DEVELOPMENT OF GLASS COMPOSITIONS TO IMMOBILIZE ALKALI, ALKALINE EARTH, LANTHANIDE AND TRANSITION METAL FISSION PRODUCTS FROM NUCLEAR FUEL REPROCESSING, article, June 24, 2009; South Carolina. (digital.library.unt.edu/ark:/67531/metadc932626/m1/4/: accessed September 23, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.