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Mercury-free dissolution of aluminum-based nuclear material: from basic science to the plant

Crooks III W., Crown J., Dunn K., Mickalonis J., Murray A., Navratil J.

Nukleonika

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2003

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Vol. 48, nr 4

163-169

EN

Conditions were optimized for the first plant-scale dissolution of an aluminum-containing nuclear material without using mercury as a catalyst. This nuclear material was a homogeneous mixture of plutonium oxide and aluminum metal that had been compounded for use as the core matrix in Mark 42 nuclear fuel. B ecause this material had later failed plutonium distribution specifications, it was rejected for use in the fabrication of Mark 42 fuel tubes, and was stored at the Savannah River Site (SRS) awaiting disposition. This powder-like material was composed of a mixture of ~80% aluminum and 11% plutonium. Historically, aluminum-clad spent nuclear fuels have been dissolved using a mercuric nitrate catalyst in a nitric acid (HNO3) solution to facilitate the dissolution of the bulk aluminum cladding. Developmental work at SRS indicated that the plutonium oxide/aluminum compounded matrix could be dissolved using boric acid-hydrofluoric acid-nitric acid as a substitute for mercury. Various mercury-free conditions were studied to evaluate the rate of dissolution of the Mark 42 compact material and to assess the corrosion rate to the stainless steel dissolver. The elimination of mercury from the dissolution process fit with waste minimization and industrial hygiene goals to reduce the use of mercury in the United States. The mercury-free dissolution technology was optimized for Mark 42 compact material in laboratory-scale tests, and successfully implemented at the plant.

2

Magnetic filtration/adsorption process for Snake River Plain Groundwater Treatment

Cotten G., Eldredge H., Navratil J.

Nukleonika

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2003

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Vol. 48, nr 1

17-23

EN

A magnetic filtration/adsorption process has been evaluated for development for groundwater treatment at the Idaho National Engineering and Environmental Laboratory (INEEL). The process uses inexpensive magnetite (FeOźFe2O3) in a supported mode surrounded by an external magnetic field. Prior studies have been shown to remove actinides and fission products in laboratory studies. This research has focused on supporting magnetite in an economical manner that promotes both magnetic filtration/adsorption of metal species and satisfactory water flow. The process utilizes the natural metal ion adsorptive properties of magnetite as well as the High Gradient Magnetic Separation (HGMS) effect for removing metal colloids and submicron particles. Results are presented on scoping studies for developing the process for groundwater treatment at the INEEL.

3

Actinide ion exchange technology in the back end of the nuclear fuel cycle

Navratil J., Wei Y.

Nukleonika

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2001

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Vol. 46, nr 2

75-80

EN

Ion exchange is used extensively in nuclear power technology, especially for uranium ore processing, removal of contaminants from power reactor waters and in the back end of the nuclear fuel cycle. In nuclear fuel reprocessing plants, ion exchange is used for the purification of actinide elements for further use, for the solidification of low- and medium-active waste solutions, and for the partitioning of high-level wastes. This paper reviews selected technological uses of ion exchange in these operations for recovery, separation and purification of selected actinides (Pu, U, Np, etc.). Recent research and development on ion exchange technologies for actinides are also summarized.