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  Institute for Reactor Safety and Reactor Technology (Univ.-Prof. Dr. rer. nat. Hans-Josef Allelein)

EU-COMAS - Investigations on Corium on Material Surfaces

The EU-COMAS-Project (COMAS = Corium on Material Surfaces) is sponsored by the European Union and the German Federal Ministry for Education, Science, Research and Technology (BMBF).
Within the EU-COMAS-Project, large-scale experiments (up to 3000 kg at Siempelkamp Nuklear- und Umwelttechnik GmbH & Co) are carried out to investigate expansion behaviour of prototype core meltdowns.

Of particular interest to the research is the melting and expansion behaviour onto various substrate materials, upon which temperatures in excess of 2000°C will be reached. Moreover, the COMAS-experiments will be analysed with emphasis on the special qualities of the heat transfer patterns. The experiments serve as an extension to the base knowledge with a view to further development and the verification of computer codes. Validation of the core-catcher concepts with a large surface area for spreading, such as the EPR should also be achieved.
The HTCM-Project was realised parallel to the COMAS-experiments in the generated melts.

2-D extension of a prototypical meltdown

Aims of the COMAS-Project:


Project partners in EU-COMAS:

Participation of the LRST:

The main experiment inspection consists of a comprehensive sample analysis. Among other things, both the composition and structure of the sample material are to be determined. In addition to this, pieces of the melt material are studied using a scanning electron microscope and also using EDX-Analysis. The following two pictures show exemplary back-scatter images from the REM and the phase colour coding after the image analysis.

Scan-Electron-Microscope-Image. Magnificationfactor 2000:1Same Image after color-coding the plases by image-analysis