Lead-bismuth eutectic fluid mechanic instrumentation validation program (Postdoc)

The MYRRHA Accelerator-driven system requires measurement technologies for fluid mechanic properties especially adapted to its use of lead-bismuth eutectic (LBE) as coolant. Besides its relatively high density, corrosivity, opaqueness, weak specific electric and thermal conductivity the sensors being in contact with the liquid are facing elevated temperatures in the range from 200 to 450°C or even more. Although in the past decades a lot of progress has been achieved in developing liquid metal adapted measurement devices in the context of sodium operated fast breeder reactors only part of the knowledge can be transferred to lead alloy cooled systems because of its specific properties.

While using measurement devices one must clearly distinguish between operational and maintenance purposes and scientific ones having different requirements concerning resolution, reliability, response time, lifetime, accuracy etc. Moreover, fluid mechanic measurement devices are in principle divided into two classes of systems. One is the measurement of global quantities, like the flow rate, the pressure in the system or the mean temperatures. This class of devices is dedicated to reactor applications and the use in liquid metal loop operation. The other class is formed by measurement of local quantities like the velocity and void distribution, the heat flux, the surface structure and shape, which is necessary to capture effects occurring in generic scientific problems. The detection of these particular effects in benchmark problems allows the development of new physical models or the validation computational fluid dynamic (CFD) simulations.

The purpose of the post-doctoral research is the experimental characterization, qualification and calibration of fluid mechanic instrumentation in representative LBE conditions in support of the experimental programs (including both liquid metal loop operation for technology qualification and CFD benchmark experiments) and of the reactor instrumentation design program.

The main parameters of interest are the LBE temperature, pressure, flow rate and velocities, for each of which the various existing measurement techniques should be evaluated. Also monitoring of other LBE parameters like chemical purity could be considered. The emphasis of the work will not be on the development of new technologies.  Instead, the candidate is expected to implement, adapt and optimize existing technologies for application in LBE test loops and in MYRRHA.