Development and application of robust electrical measurement and imaging techniques for high-resolution acquisition of thermal-hydraulic parameters in large-scale nuclear safety research test facilities (joint research project ROBIN)

Sub-Project:

Development of measurement technology for recording flow parameters in large-scale nuclear safety research test facilities

Motivation:

In the joint research project, new robust imaging techniques are being developed that will make it possible in the future to instrument large-scale test facilities in reactor safety research in such a way that thermal-hydraulic data can be recorded in CFD quality, i.e. with very high spatial and temporal resolution. Such measurement techniques exist today for single-effect studies primarily at moderate operating conditions, such as air-water operation at ambient pressure and ambient temperature. Hot and pressure-resistant instrumentation, on the other hand, is still very rare.

Objectives:

The focus of the project is on new approaches that address actual "instrumentation gaps" identified in a critical analysis of the state of the art. With the concept of an "imaging pipe", the analysis of two-phase flows in risers along the pipe axis, for example for unstable two-phase flows, is made possible for the first time. A thermoanemometry grid sensor is being further developed for water velocity measurements. Electrical impedance tomography will enable the non-invasive detection of two-phase flows in large pipelines.

In the sub-project, the following sub-objectives will be implemented:

• Development of sensor technology for spatially resolved measurement of gas content and flow velocity according to the principle of thermal anemometry,
• Comparative evaluation of different sensor variants,
• Construction of a sensor with miniaturised transducers,
• Functional verification in the laboratory and on thermal-hydraulic test facilities.

Methods and results:

All developed measurement methods are applied within the framework of ongoing or separate experimental programmes. In the sub-project, the following tasks will be implemented:

• Design and construction of an axial wire-mesh sensor,
• Specification of transducer substrates, hot film structure and interconnection technology,
• Development of algorithms for two-phase discrimination,
• Implementation of software algorithms for data visualization,
• Experimental studies on test facilities.