VELLA WORLD

HLM TECHNOLOGIES

 

Physical and chemical properties of HLM

Great effort is dedicated in the ongoing R&D programmes to the creation of a consistent database of the lead/LBE properties of main interest. Nevertheless, the amount of data available is still limited and needs to be enlarged through dedicated experimental campaigns.
A critical review of the available information/ experimental activities regarding Pb and LBE technologies is going on as well as a subsequent identification of the properties/data of main interest for the different system (LFR, ADS, etc).
A noteworthy “Handbook on Lead-bismuth Eutectic Alloy and Lead Properties, Materials Compatibility, Thermal-hydraulics and Technologies” has been recently published by NEA.
Properties such as the speed of sound in liquid Pb, the viscosity, the thermal expansion coefficient need further investigation. Experiments meant to define these properties and their correlation versus temperature, have to be set up.
A critical review and a comparative assessment of different empirical equations for single-phase heat transfer in rod bundles of a lead (or LBE) cooled fast reactor is going on, to outline the more suitable correlation in each condition relevant for ADS and LFR.

Oxygen sensors and control

Several activities devoted to the development of oxygen sensors and control systems in LBE have been carried out and still are going on.
The control of the oxygen activity in HLM, by adding an Ar+steam/hydrogen gas mixture, has been developed for normal operation of LBE loops. Other systems, such as separate addition of oxygen and hydrogen and PbO/Pb equilibrium, have been also applied.
The extension of the knowledge gained in loop systems is now going to be transferred to pool-type configurations.
In parallel, the translation of the knowledge gained in LBE to pure lead is going on.
The characterisation, standardised calibration and validation of oxygen meters performances is foreseen in terms of: temperature coefficients; resistance to thermal shocks; life time; time drift.

Handling of impurities, aerosols and slags

The testing of new filters and purification procedures on large facilities is going on indifferent projects.
As in the case of oxygen sensors and control systems, the knowledge gained in LBE is now transferred to pure lead.