Development of a system for tracking objects in a confined space

Abstract

The Pebble Bed Modular Reactor (PBMR) is one of the alternative generation options that Eskom is currently investigating to replace their old coal-fired plants. The PBMR plants are smaller than conventional plants and therefore require a smaller lead time to construct. If successfully demonstrated, the plants could comprise 20 % of the countries nuclear build programme. The flow of fuel spheres through the Reactor Pressure Vessel (RPV), a vertical cylinder with height 27 m and diameter 6.2 m, determines the energy level in the RPV. If the flow paths of these fuel spheres are known, reactor geometries can be optimised. Currently the flow paths of the spheres are either estimated based on previous results from different reactor geometries, or simulated using PFC-3D simulation software, based on spherical models that doesn’t correspond to the actual spheres. A system able to accurately track the spheres through the RPV will enable further research to be done into the flow of the spheres. In this research we aim to develop a concept system that could be used as the base for a system that can track objects accurately in a confined space. Such a system could be used to track the flow of the spheres through a model of the RPV. During our literature study on tracking systems we found that it is hard to compare different tracking systems with each other, due to the diversity in the applications of these systems. We found a few surveys and taxonomies, but these were confined to specific application domains, and thus couldn’t be used to characterise and classify systems outside of the domain. Based on our need to compare different systems from different application domains with one another we developed a characterisation and classification method based on the basic aspects of tracking systems identified during our literature study. The method enables the characterization and classification of a tracking system to a general form. Using this method enables us to compare systems from various different application domains.

The concept system is developed based on radio interferometric positioning. We derive a mathematical model for the concept system and use this model to implement an ideal deterministic simulation of the system. We use the simulation and follow an empirical investigation to determine the effect of certain parameters on the accuracy of the system. The results obtained with these simulations are then used to make recommendations concerning the setup of the concept system. Using these recommendations as inputs, a simulation is done for a set of 20 random positions. The maximum localization error made during the simulations was 6.5 mm, much smaller than the 3 cm resolution required by the system. This implies that the concept system is a viable option for tracking the spheres through the RPV model.