Design, calibration and validation of a dip tube system for nuclear tank volume measurement

SCK•CEN Mentor

Van Hoecke Karen, kvhoecke@sckcen.be, +32 (0)14 33 82 01

Expert group

Radiochemistry

SCK•CEN Co-mentor

Albarracín Sánchez Ferran , fasanche@sckcen.be , +32 (0)14 33 82 12

Introduction

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 [1]

Objective

The main objective of the thesis is to assemble a custom dip tube system, to calibrate and test it on a prototype reactor vessel for the nuclear facility. The R&D will first be focused on the optimization of various parameters, such as the dimensions and diameter of the tubes, specifications of the pressure sensors and air flow rate. Secondly, calibration of the reactor vessel is performed, which links the measured pressure to batch volume. Special attention is hereby paid to correct for thermal expansion of the dip tube system and the reactor. To evaluate the accurracy of the dip tube system output, a reference measurement of reactor content is made using a balance, which will allow to plot residuals of the dip tube system output versus batch volume. The next objective of the practical work is to evaluate the robustness of the system and to estimate its measurement uncertainty by either a bottom-up or top-down approach. Finally, a last objective is to write a program code to simplify readout of the system and calculation of final results with their associated measurement uncertainty.

Reference:

[1] ISO 18213-1: 2007 (E) Nuclear fuel technology — Tank calibration and volume determination for nuclear materials accountancy — Part 1: Procedural overview.

The minimum diploma level of the candidate needs to be

Professional bachelor , Academic bachelor

The candidate needs to have a background in

Chemistry , Electromechanics