Spatially resolved measurement of gas phase temperature and velocity in the subchannels of a fuel element during dry-out


Spatially resolved measurement of gas phase temperature and velocity in the subchannels of a fuel element during dry-out

Arlit, M.; Partmann, C.; Schleicher, E.; Hampel, U.

After the Fukushima accident the spent fuel pool has got a stronger focus in nuclear safety research. The objective of the German national joint project SINABEL (Safety of wet storage facilities for spent fuel) is the experimental investigation and modelling of the thermal hydraulics of fuel elements (10 fuel rods in square, D = 10 mm, P/D = 1.24) in the pool dry-out phase. Key parameters for validation of the models are the steam temperatures and velocities in the subchannels. Due to the complex geometry and the thermal insulation of the test facility there is a strong limitation in the optical and mechanical accessibility for measurements. As a result there is a need of novel measurement techniques to provide spatially resolved gas phase temperatures and velocities.
Our approach is a modified wire-mesh sensor that is usually used for phase discrimination in two-phase flows via the measurement of conductivity or capacity in the crossing points of the wires. In the new sensor concept we integrate special miniaturized converters, which are resistance thermometers for the temperature and velocity measurement. The advantage of this technique is the possibility to overheat the sensor by increasing the current through the sensor. By controlling the sensor temperature the use of the thermal anemometry principle becomes possible.
The challenges in the development of this combining measurement system are the boundary conditions. The range of the steam velocity is down to 0.01 m/s. The temperature range is from the water boiling temperature of 100 °C up to 500 °C overheated steam. As a result of this there are high requirements in temperature compensation and the mechanical resistivity of the measurement setup.
In the contribution we will describe both the new sensor technology as well as its application in thermal hydraulic experiments for advanced analysis of safety issues for the spent fuel pool.

Keywords: Thermal anemometry; Wire-mesh sensor; temperature grid sensor; velocity grid sensor

  • Contribution to proceedings
    NURETH-16 - 16th International Topical Meeting on Nuclear Reactor Thermalhydraulics, 30.08.-04.09.2015, Chicago, USA
  • Poster
    NURETH-16 - 16th International Topical Meeting on Nuclear Reactor Thermalhydraulics, 30.08.-04.09.2015, Chicago, USA

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Publ.-Id: 21993