Determination of the Rate of Formation of Hydroceramic Waste Forms made with INEEL Calcined Wastes
The formulation, synthesis, characterization and hydration kinetics of hydroceramic waste forms designed as potential hosts for existing INEEL calcine high-level wastes have been established as functions of temperature and processing time. Initial experimentations were conducted with several aluminosilicate pozzolanic materials, ranging from fly ash obtained from various power generating coal and other combustion industries to reactive alumina, natural clays and ground bottled glass powders. The final selection criteria were based on the ease of processing, excellent physical properties and chemical durability (low-leaching) determined from the PCT test produced in hydroceramic. The formulation contains vermiculite, Sr(NO32), CsC1, NaOH, thermally altered (calcined natural clay) and INEEL simulated calcine high-level nuclear wastes and 30 weight percent of fluorinel blend calcine and zirconia calcine. Syntheses were carried out at 75-200 degree C at autogeneous water pressure (100% relative humidity) at various time intervals. The resulting monolithic compact products were hard and resisted breaking when dropped from a 5 ft height. Hydroceramic host mixed with fluorinel blend calcine and processed at 75 degree C crumbled into rice hull-side grains or developed scaly flakes. However, the samples equally possessed the same chemical durability as their unbroken counterparts. Phase identification by XRD revealed that hydroceramic host crystallized type zeolite at 75-150 degree C and NaP1 at 175-200 degree C in addition to the presence of quartz phase originating from the clay reactant. Hydroceramic host mixed with either fluorinel blend calcine or zirconia calcine crystallized type A zeolite at 75-95 degree C, formed a mixture of type A zeolite and hydroxysodalite at 125-150 degree C and hydroxysodalite at 175-200 degree C. Quartz, calcium fluoride and zirconia phases from the clay reactant and the two calcine wastes were also detected. The PCT test solution conductivity, pH and analytical concentration measured as a function of time decrease exponentially. In some cases nitrate, sulfate, chloride and fluoride ion concentrations increased with time and processing temperature with respect to the reference sample. The increasing concentration of these ions was due to the lack of formation of crystalline phases that can incorporate them in their structures, especially cancrinite. Another plausible explanations for their increase was due to the continuous withdrawal of cations with time, for example sodium to form zeolites, thereby increase their concentrations.
- Research Organization:
- Pennsylvania State University (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FG07-98ID13649
- OSTI ID:
- 801196
- Report Number(s):
- DOE/ID/13649; TRN: US0203984
- Resource Relation:
- Other Information: PBD: 15 Oct 2001
- Country of Publication:
- United States
- Language:
- English
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