Effects of Radiation Exposure on Glass Alteration in a Steam Environment

Abstract

Several Savannah River Plant (SRL) glass compositions were reacted in steam at temperatures of 150°C to 200°C. Half of the tests utilized actinide-doped monoliths and were exposed to an external ionizing gamma source, while the remainder were doped only with U and reacted without gamma exposure. All glass samples readily reacted to form secondary mineral phases within the first week of testing. An in situ layer of smectite initially developed on nonirradiated SRL 202 glass test samples. After 21 days, a thin layer of illite was precipitated from solution onto the smectite layer. A number of alteration products including zeolite, Ca-silicate, and alkali or alkaline earth uranyl silicate phases were also distributed over most sample surfaces.

In the irradiated SRL 202 glass tests, up to three layers enveloped rounded, and sometimes fractured, glass cores. After 35 to 56 days these remnant cores were replaced by a mottled or banded Fe- and Si-rich material. The formation of some secondary mineral phases also has been accelerated in the irradiated tests, and in some instances, the irradiated environment may have led to the precipitation of a different suite of minerals. The alteration layer(s) developed at rates of 2.3 and 32 μm/day for the nonirradiated and irradiated SRL 202 glasses, respectively, indicating that layer development is accelerated by a factor of ~10 to 15X due to radiation exposure under the test conditions.

Meeting Name

16th International Symposium on the Scientific Basis for Nuclear Waste Management (1992: Nov. 30-Dec. 4, Boston, MA)

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Geological Repositories; Radiation; Radioactive Waste Disposal; Steam; Geologically Unsaturated Environment; Radiation Exposure; Steam Environment; Waste Glass Alteration; Borosilicate Glass

International Standard Book Number (ISBN)

1558991891

International Standard Serial Number (ISSN)

0272-9172

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1993 Materials Research Society (MRS), All rights reserved.

Publication Date

01 Nov 1993

Link to Full Text

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