FUEL CONDITIONING FACILITY ELECTROREFINER VOLUME CALIBRATION

In one of the electrometallurgical process steps of the Fuel Conditioning Facility (FCF), the in-process nuclear material is dissolved in the electrorefiner tank in an upper layer of a mixture of liquid LiCl-KCl salt and a lower layer of liquid cadmium. The electrorefiner tank, as most process tanks, is not a smooth right-circular cylinder for which a single linear volume calibration curve could be fitted over the whole height of the tank. Rather, the tank contains many internal components, which cause systematic deviations from a single linear function. The nominal operating temperature of the electrorefiner is 500°C although the salt and cadmium are introduced at 410°C.(1) The operating materials and temperatures preclude multiple calibration runs at operating conditions. In order to maximize the calibration information, multiple calibra-tion runs were performed with water at room temperature. These data allow identification of calibration segments, and preliminary estimation of the calibration function and calibration uncertainties. The final calibration function is based on a combination of data from the water calibrations and the measurements made during the filling of the electrorefiner with salt and cadmium for operation.