British Nuclear Fuels Plc

Ewan Robert Maddrell

Melody Lyn Carter

The present invention relates to an immobilizing medium for the encapsulation of radioactive waste. The waste immobilizing medium has a sodium silicate based glass matrix in which there is contained radioactive waste wherein the waste comprises one or more inert metal components and one or more fission products. At least a portion of the inert metal components are dissolved in the glass matrix and increase its durability. As a result, the waste immobilising medium is highly durable and leach resistant and is suitable for long term storage of radioactive waste. The inert metal components preferably comprise iron, nickel and chromium.

Encapsulation of radioactive waste using a sodium silicate based glass matrix

A ceramic waste immobilizing material for the encapsulation of high level radioactive waste (HLW), e.g. resulting from the reprocessing of irradiated nuclear fuel. The ceramic waste immobilising material enables waste ions from at least fission products in irradiated nuclear fuel to be dissolved in substantially solid solution form. The ceramic waste immobilising medium has a matrix comprising phases of hollandite, perovskite and zirconolite in which the waste ions are dissolved. The invention also includes a method of immobilizing HLW from reprocessed nuclear fuel assemblies comprising the steps of mixing a liquor containing the HLW with a precursor material comprising oxides or oxide precursors of at least titanium, calcium and barium to form a slurry, drying the slurry, and calcining the dried slurry under a reducing atmosphere to form a powder comprising 30&#x2013;65 weight % waste.

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Cumbria, United Kingdom

Ewan Robert Maddrell