Thermal Stabilization of {sup 233}UO{sub 2}, {sup 233}UO{sub 3}, and {sup 233}U{sub 3}O{sub 8}

Thein, S.M.

Oak Ridge National Laboratory

关键词: Heating;    Pressurization;    Radiolysis;    Oxides;    Uranium Oxides;   

DOI  :  10.2172/814072
RP-ID  :  ORNL/TM-2000/82
RP-ID  :  AC05-00OR22725
RP-ID  :  814072

美国|英语

来源: UNT Digital Library

【 摘 要 】

This report identifies an appropriate thermal stabilization temperature for {sup 233}U oxides. The temperature is chosen principally on the basis of eliminating moisture and other residual volatiles. This report supports the U. S. Department of Energy (DOE) Standard for safe storage of {sup 233}U (DOE 2000), written as part of the response to Recommendation 97-1 of the Defense Nuclear Facilities Safety Board (DNFSB), addressing safe storage of {sup 233}U. The primary goals in choosing a stabilization temperature are (1) to ensure that the residual volatiles content is less than 0.5 wt % including moisture, which might produce pressurizing gases via radiolysis during long-term sealed storage; (2) to minimize potential for water readsorption above the 0.5 wt % threshold; and (3) to eliminate reactive uranium species. The secondary goals are (1) to reduce potential future chemical reactivity and (2) to increase the particle size thereby reducing the potential airborne release fraction (ARF) under postulated accident scenarios. The prevalent species of uranium oxide are the chemical forms UO{sub 2}, UO{sub 3}, and U{sub 3}O{sub 8}. Conversion to U{sub 3}O{sub 8} is sufficient to accomplish all of the desired goals. The preferred storage form is U{sub 3}O{sub 8} because it is more stable than UO{sub 2} or UO{sub 3} in oxidizing atmospheres. Heating in an oxidizing atmosphere at 750 C for at least one hour will achieve the thermal stabilization desired.