The R&D effort on lead-bismuth technology is focused on key issues in support of the design of the MYRRHA ADS.
- Spallation loop & target thermal-hydraulics
- Vacuum system
- Chemistry control
- Fuel pin & assembly thermal-hydraulics
- Lead-Bismuth eutectic/water interaction
- Radiotoxicity issues
|Chemistry and oxygen control
Spallation loop & target thermal-hydraulics
A significant effort was put into the development of a compact windowless spallation target. The hydraulic feasibility of the target was demonstrated and different routes for further optimizing have been identified. These were integrated in a new target design that has proven to work by CFD simulations and will be experimentally tested shortly.
The vacuum compatibility of the windowless target was demonstrated as both outgassing and surface heating due to the beam impact were shown to be sufficiently low. Liquid metal evaporation and deposition is under investigation. Beam transient effects on the target, possibly causing splashes are investigated numerically. First results are encouraging but clearly further research is required.
Oxygen control was chosen as the method to manage corrosion issues of the LBE and the structural materials in the ADS. For this purpose, sensitive oxygen sensors and adequate oxygen control methods have been developed. Further steps in this field will depend on the basis of the evaluation of long-term corrosion data which is becoming available via the EUROTRANS project.
For removal of LBE from structural materials and components, several small-scale methods have been studied. Here a more detailed research program must be undertaken to select the most suitable large scale cleaning methods.
Fuel pin & assembly thermal-hydraulics
A substantial part of the thermal-hydraulic design of the fuel-pin and assemblies relies of numerical simulations. To validate the reliability of numerical tools, the existing physical models are being re-evaluated for LBE. Relevant experiments have been set-up and were performed within the EUROTRANS project.
An important safety issue in the liquid metal cooled ADS is possible LBE/water interactions. For this purpose, the SIMMER-III code that is used to asses possible steam ingress and sloshing in the ADS design is subjected to an extensive validation program based on experiments in ADS relevant conditions within the EUROTRANS project.
A second safety aspect involves specific radiotoxicity problems related to liquid metal cooled ADS systems. Here the R&D is concentrated on the major radiotoxicity risks that are related to the formation and release of long-lived 194Hg in the spallation target loop and of the alpha isotope 210Po. New research on the production and release rates of the latter has been performed in the EUROTRANS project. With these data a new assessment for the necessity of 210Po removal, in contrast to confinement will be performed. Several promising extraction methods have been identified. Trapping techniques for Hg are available and have been applied in the LBE spallation target developed for the Megapie project.