Doctoral Dissertations

Abstract

"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).

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.

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.

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.

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.

Advisor(s)

Day, D. E.

Committee Member(s)

Huebner, Wayne
Mattox, Douglas M.
Moore, Robert E., 1930-2003
Switzer, Jay A., 1950-

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Ceramic Engineering

Publisher

University of Missouri--Rolla

Publication Date

Spring 1997

Journal article titles appearing in thesis/dissertation

  • Immobilization of high-level radioactive sludges in iron phosphate glass
  • Immobilization of radioactive 137Cs and 90Sr in iron phosphate glass
  • Immobilization of spent nuclear fuel in iron phosphate glass

Pagination

xxii, 208 pages

Note about bibliography

Includes bibliographical references.

Rights

© 1997 Melissa Gay Mesko, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 7264

Print OCLC #

45425333

Electronic OCLC #

1079066029

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