Immobilization of radioactive materials in iron phosphate glass

<p>"The current study investigates the feasibility of using iron phosphate glass for the immobilization of radioactive wastes considered incompatible with borosilicate glass. Wastes may be incompatible with borosilicate glass due to high phosphorus content (Hanford tank sludges), the presence of halides (CsCl and SrF₂ capsules), or large amounts of uranium (SNF).</p> <p>Between 20 and 60 wt% Hanford tank sludge was vitrified with an iron phosphate glass at ≤ 1200°C in 1 hour. The chemical durability of iron phosphate glassy wasteforms was as good as, or better than a reference borosilicate glass (10^-9 g/cm²/min) in distilled water at 90°C. Adding 7 wt% CaF₂ to the batch decreased the melt temperature by 50°C and the melt viscosity without affecting the chemical durability of the glassy wasteform.</p> <p>Iron phosphate glasses made with CsCl and SrF₂ were prepared at ≥ 950°C in 2 hours. Chemical analysis indicates neither Cs or Sr are volatilized from the batch. The chemical durability of glasses made with CsCl or SrF₂ was as good as, or better than a reference borosilicate glass (10^-9 g/cm²/min) in distilled water at 90°C. Glasses made with both CsCl and SrF₂ had a better chemical durability from pH 2 to pH 12.</p> <p>Iron phosphate glasses containing 15 wt% SNF were produced by melting at 1150°C for 2 hours. Adding a small amount (as little as 2.5 wt%) of Na₂O decreased melt viscosity and reduced devitrification tendency. The chemical durability of all but one of the glassy wasteforms containing SNF was as good as, or better than a borosilicate reference glass (10^-9 g/cm²/min) in distilled water at 90°C.</p> <p>The chemical durability of all of the iron phosphate compositions in the current study increased as the amount of iron and aluminum in the batch increased. The durability of the iron phosphate glasses was further improved by the formation of an iron-rich surface layer and the buffering action which occurs as a phosphate glass reacts with water"--Abstract, page iv.</p>

Name thesis:degree_name

Ph. D. in Ceramic Engineering

Grantor

University of Missouri--Rolla

Year dc:date.available

2016

Author dc:creator

• Mesko, Melissa G.

• Ceramic Materials

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/1326

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-2328