Uranium-233-Bearing Salt Preparation for the Molten Salt Reactor Experiment

The Molten Salt Reactor Experiment has been refueled with an enriching salt concentrate, ⁷LiFUF₄ (73 to 27 mole%). Sixty-three kilograms of this was prepared in a shielded cell in the Thorium-Uranium Recycle Facility at Oak Ridge National Laboratory. The preparation process involved reducing ²³³UO₃ to UO₂ by treatment with hydrogen, converting the ²³³UO₂ to ²³³UF₄ by hydrofluorination, and fusing the ²³³UF₄ with LiF. Its preparation in a shielded cell was required because of the high ²³²U content (222 ppm) of the ²³³U. The product salt, containing 39 kg of uranium (91.4% ²³³U), was low in oxide content (50 ppm) and the concentration of the corrosion products, chromium, iron, and nickel, was minimal at less than (0.05%) total.