Determination of molten salt mass using 22Na tracer mixed with 154Eu and 137Cs

A longstanding issue with irregularly shaped molten salt containers is the accurate determination of the contained salt mass. A technique known as radioactive tracer dilution was previously validated at a benchtop scale, and further investigated in this work to validate this method on a more significant salt mass (up to 122 g) and more realistic spectroscopic environment. Since the end use goal for this process is in an electrorefiner that reprocesses spent nuclear fuel, it was decided to add the abundant fission product 137 Cs to a mixture of molten salt that contained a tracer isotope, 22 Na, and interfering fission product, 154 Eu. The study has proved that the tracer was homogeneously mixed with the salt, and the accuracy of the method is preserved even with the addition of 154 Eu and a large amount of 137 Cs activity. The self-attenuation from the volumetric salt sample and the dead time are recognized, but remedies are presented which rectify the issue.