Appendix A. Technical Bases for 233U Packaging and Storage Criteria

DOE-STD-3028-2000

Appendix A. Technical Bases for 233U Packaging and Storage Criteria

This Appendix summarizes the technical bases for the criteria in this Standard. Section numbers

in this Appendix correspond to the section numbers in the body of the Standard and provides

guidance where applicable. The reader is directed to the primary technical source information

and the 233U Technical Handbook [Storch 1999] for further details.

Development of this Standard was modeled on the Standard for plutonium [DOE 1999].

Although plutonium and uranium have significant physical/chemical differences, many of the

storage issues are similar. Consequently, this Standard makes use of plutonium studies for

issues that are material independent or for issues where the plutonium behavior bounds the 233U

behavior (e.g., alpha radiolysis).

A.1

PURPOSE AND SCOPE

This Standard establishes criteria for packaging, and long-term safe storage of separated 233U-

bearing metals and oxides. Storage packages that meet these criteria should maintain their

integrity (i.e., should not require further repackaging) for a minimum of 50 years. The bulk of

these materials are stored at ORNL and INEEL as solid forms including metals, oxide powders,

ceramic oxide pellets, and oxide monoliths. This Standard does not apply to 233U-bearing

liquids, residues, wastes, spent fuels, irradiated targets, in-process materials or small quantities

involved in research and development studies. Those materials are either addressed by other

storage programs or are not germane to the intended safe storage activity.

With the exception of oxide from the Consolidated Edison Uranium Solidification Project

(CEUSP) , the material covered by this Standard is nearly isotopically pure 233U with trace

amounts of 232U. Isotopes of uranium that may be present (with their half-lives in parentheses),

include 238U (4.5 x 109 y), 236U 2.4 x 107 y), 235U (7.0 x 108 y), 234U (2.4 x 105 y),

233

U (1.6 x 105 y), and 232U (69 y). Uranium-233 and its associated isotope 232U are man-made.

They present potentially more severe radiological hazards than the naturally occurring uranium

isotopes do. An isotopic level of 0.66 wt % 233U (excluding 232U) in weapons-grade highly

enriched uranium (HEU) is the 233U isotopic concentration at which the specific activity of 233U

exceeds that for uranium highly enriched in the 235U isotope [Bereolos et al. 1998]. Any 232U

present will lower this bound even further.