Encapsulation of spent ceramic nuclear fuel
OwnerTihiro Ohkawainventor
Life of this patent
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Abstract
A method for vitrifying a plurality of nuclear waste kernels includes coating the kernels with a glass layer, and mixing the glass-coated kernels in a glass melt. Subsequent cooling solidifies the glass melt and vitrifies the nuclear waste kernels in bulk vitrification glass. Importantly, the glass layer has a softening temperature that is higher than the softening temperature of the glass melt. The glass layer also has a variable thermal expansion coefficient across the layer. Additionally, the glass melt has substantially the same specific gravity as the glass-coated kernels in order to effect a uniform distribution of the glass-coated kernels throughout the bulk vitrification glass.
Claims20
A method for vitrifying a plurality of kernels of nuclear waste comprising the steps of:
- coating the kernels with a glass layer having a variable thermal expansion coefficient across the glass layer, and having a softening temperature;
- mixing the plurality of glass-coated kernels with a glass melt to form a mixture, wherein the glass melt and the kernels have a substantially same specific gravity to obtain a substantially uniform distribution of the glass-coated kernels throughout the glass melt, and further wherein the glass melt has a softening temperature lower than the softening temperature of the glass layer;
- and
- cooling the mixture to solidify the glass melt and vitrify the kernels therein.
A method for vitrifying a plurality of nuclear waste kernels wherein the kernels have a core including the nuclear waste, a layer of silicon carbide surrounding the core, a layer of carbon surrounding the silicon carbide layer, and wherein the kernels are embedded in graphite, the method comprising the steps of:
- removing the graphite and the carbon layer from the plurality of kernels;
- coating the silicon carbide layer of each kernel with a glass layer having a thermal expansion coefficient, and having a softening temperature;
- varying the thermal expansion coefficient across the glass layer during the coating step;
- mixing the plurality of glass-coated kernels with a glass melt to form a mixture, wherein the glass melt and the kernels have a substantially same specific gravity to obtain a substantially uniform distribution of the glass-coated kernels throughout the glass melt, and further wherein the glass melt has a softening temperature lower than the softening temperature of the glass layer;
- and
- cooling the mixture to solidify the glass melt and vitrify the kernels therein.
A device for storing nuclear waste which comprises:
- a glass container having a softening temperature;
- and
- a plurality of kernels embedded in said glass container, said plurality of kernels having a core including said nuclear waste, and a glass layer surrounding said core, said glass layer having a variable thermal expansion coefficient across the glass layer, and having a softening temperature higher than said softening temperature of said glass container, and wherein said kernels and said glass container have a substantially same specific gravity to obtain a substantially uniform distribution of said kernels throughout said glass container.
Dependencies are inferred from the claim text.