TY - JOUR
T1 - Mineral assemblage transformation of a metakaolin-based waste form after geopolymer encapsulation
AU - Williams, Benjamin D.
AU - Neeway, James J.
AU - Snyder, Michelle M.V.
AU - Bowden, Mark E.
AU - Amonette, James E.
AU - Arey, Bruce W.
AU - Pierce, Eric M.
AU - Brown, Christopher F.
AU - Qafoku, Nikolla P.
N1 - Publisher Copyright:
© 2016 Elsevier B.V. All rights reserved.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - Mitigation of hazardous and radioactive waste can be improved through conversion of existing waste to a more chemically stable and physically robust waste form. One option for waste conversion is the fluidized bed steam reforming (FBSR) process. The resulting FBSR granular material was encapsulated in a geopolymer matrix referred to here as Geo-7. This provides mechanical strength for ease in transport and disposal. However, it is necessary to understand the phase assemblage evolution as a result of geopolymer encapsulation. In this study, we examine the mineral assemblages formed during the synthesis of the multiphase ceramic waste form. The FBSR granular samples were created from waste simulant that was chemically adjusted to resemble Hanford tank waste. Another set of samples was created using Savannah River Site Tank 50 waste simulant in order to mimic a blend of waste collected from 68 Hanford tank. Waste form performance tests were conducted using the product consistency test (PCT), the Toxicity Characteristic Leaching Procedure (TCLP), and the single-pass flow-through (SPFT) test. X-ray diffraction analyses revealed the structure of a previously unreported NAS phase and indicate that monolith creation may lead to a reduction in crystallinity as compared to the primary FBSR granular product.
AB - Mitigation of hazardous and radioactive waste can be improved through conversion of existing waste to a more chemically stable and physically robust waste form. One option for waste conversion is the fluidized bed steam reforming (FBSR) process. The resulting FBSR granular material was encapsulated in a geopolymer matrix referred to here as Geo-7. This provides mechanical strength for ease in transport and disposal. However, it is necessary to understand the phase assemblage evolution as a result of geopolymer encapsulation. In this study, we examine the mineral assemblages formed during the synthesis of the multiphase ceramic waste form. The FBSR granular samples were created from waste simulant that was chemically adjusted to resemble Hanford tank waste. Another set of samples was created using Savannah River Site Tank 50 waste simulant in order to mimic a blend of waste collected from 68 Hanford tank. Waste form performance tests were conducted using the product consistency test (PCT), the Toxicity Characteristic Leaching Procedure (TCLP), and the single-pass flow-through (SPFT) test. X-ray diffraction analyses revealed the structure of a previously unreported NAS phase and indicate that monolith creation may lead to a reduction in crystallinity as compared to the primary FBSR granular product.
KW - Feldspathoid minerals
KW - Fluidized bed steam reformer
KW - Low-activity waste
KW - Waste form leach test
UR - http://www.scopus.com/inward/record.url?scp=84968403354&partnerID=8YFLogxK
U2 - 10.1016/j.jnucmat.2015.12.023
DO - 10.1016/j.jnucmat.2015.12.023
M3 - Article
AN - SCOPUS:84968403354
SN - 0022-3115
VL - 473
SP - 320
EP - 332
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
ER -