BMU Project
Behaviour of caesium and strontium as contaminants during the thermal treatment of waste, the subsequent maturation of the resulting slags and the leaching behaviour in the leachate regime
| Editor: | M. Sc. Martin Dunker |
| Funding institution: | Federal Ministry for the Environment, Nature Conservation and Nuclear Safety Germany |
Project
The aim of the research project is to gain a better understanding of the behaviour of Cs and Sr during the treatment of waste in household waste incineration plants in order to be able to draw conclusions on suitable protective measures for workers and the population in the event of theoretically possible accidents. Causes for the contamination of Cs and Sr can be different radiological events in which these substances are released.
First of all, it has to be clarified in which part of the ashes (fly or bed/grate ash) the radionuclides accumulate and in which form they are present. Here, the water solubility of the contaminants is particularly relevant for the type of disposal. Furthermore, it must be determined whether these change during aging of the ashes.
For this reason, in the research project, a fuel similar to municipal waste is doped with small amounts of non-radioactive cesium and strontium compounds. Subsequently, the doped fuel will be incinerated at the Center for Energy Technology at the TU Dresden. The following processes will be used:
- Grate combustion
- Fluidized bed combustion
During combustion, the grate and fluidized bed ashes are collected and samples are taken of the fly ashes. The combustion conditions are varied with regard to temperature and oxygen supply and different doping quantities are used. The ashes are examined in the laboratories of the bifa Environmental Institute Augsburg for the two main areas of interest:
- ash aging and
- Leaching behaviour
For this purpose, ash samples are extensively examined, aged in a controlled manner and leached at different stages of ageing and in different environments. By a combination of different methods the caesium and strontium containing mineral phases as well as the solubility of the elements under different environmental conditions are determined. This is fundamental information for the prognosis of the long-term behaviour of these substances as a basis for a disposal strategy.