T-junction cross-flow mixing with thermally driven density stratification

Abstract

As a means of further elucidating turbulence-and stratification-driven thermal fatigue in the vicinity of T-junctions in nuclear power plants, a series of experiments have been conducted at the high temperature high pressure fluid-structure interaction T-junction facility of the University of Stuttgart with novel fluid measurement instrumentation. T-junction mixing with large fluid temperature gradients results in complex flow behavior, the result of density driven effects. Deionized water mixing at temperature differences of up to 232 K at 7

Temperature Profile Measurement in Simulated Fuel Assembly Structure with Wire-Mesh Technology

“…As an extension of this tool development, the purpose of this study is to structure a thermal hydraulic database that contributes to core safety design to prevent core melting. In that respect, as mentioned above, J. Kickhofel et al [10] showed that temperature measurement by WMS technology can be applied under high pressure. On the other hand, the position of this study is to quantify the temperature distribution behavior of coolant in the fuel assembly (core) and to clarify the applicability of WMS technology.…”

“…The experimental pressure is the atmospheric pressure. It is desirable to evaluate in the atmospheric pressure region [10] where the relationship between the conductivity and the sensor signal becomes linear when evaluating the sensor in bundle.…”

“…Temperature Measuring Method. The measurement principle employs that of the WMS [6,10]. To design wire electrodes comprising a squared-grid structure at the thermal field, a transmitter wire is orthogonally crossed to another receiver wire while retaining a certain distance in the order of sub-millimeters from each other.…”

“…By adopting the WMS principle, the authors' group previously developed a subchannel void sensor (SCVS) [7], a liquid film sensor [8], and a predictive technique of 3D velocity vector [9]. J. Kickhofel et al [10] applied the sensor to temperature profile measurement for T-junction crossflow mixing with thermally driven density stratification. As a result, it was clarified that the temperature distribution behavior which is mixed at a temperature difference of 232 K under high pressure of 7 MPa can be quantified when coolant supplied from each pipe.…”

“…Although laser-induced fluorescence (LIF), which measures temperature with fluorescence intensity from the target fluid, is well known as a high time-resolution method of temperature distribution [11], the optical observation with a laser sheet is difficult because nuclear and chemical reactors are almost always operated under high pressure. A method of measuring temperature profile capable of withstanding high pressure is required, and the WMS technology is suitable from the previous knowledge [10]. Here, this paper focuses on the application of WMS technology for measurement of temperature in a complex reactor core structure of LWR.…”