Currently, SCK CEN is designing a new nuclear facility to purify the residues from medical radioisotope production in Belgium. In addition, the fissile material concentration in the residues will be downblended. This creates a need to continuously report the fissile material flow throughout the installation to the International Atomic Energy Agency (IAEA). Indeed, because of the international treaty on the non-proliferation of nuclear material, Belgium declares all movements of and changes to nuclear material to the authorities, by means of nuclear material accounting. Therefore, accurate and precise determination of batch volume is necessary. A dip tube system for this purpose is to be developed and tested. A dip tube system consists of three hollow tubes of various length, an air flow supply, pressure transducers, and a temperature probe. By measuring the pressure differences between the tubes, the liquid level in a reactor vessel can be determined and with that the volume of a batch. Figure 1 gives a schematic set-up of a dip tube system.
Figure 1 - Schematic set-up of a dip tube system