Means for efficient decommissioning of reactor components and concrete shielding: Calculation of the activity inventory and their validation on drilling cores as well as mobility investigations of radionuclides (WERREBA)
- Jörg Konheiser (project leader)
- Erik Pönitz
- Astrid Barkleit
- Ghada Yassin
- Quirina Roode-Gutzmer (Ph.D. student)
The objective of the project is to obtain accurate knowledge of the radioactive nuclides produced during the power operation, the time changing of the activities and the resulting distribution of the activities in the single steps of the decommissioning. The activity distributions are to be determined plant-specifically for the reactor pressure vessel (RPV), its internals, the closure head and the first concrete shielding (biological shielding). The main focus is the experimental determination of the nuclide composition, their activity and chemical fixation in the material. The investigations are carried out on original material from both the RPV and the concrete and serve the validation and verification of the performed calculations.
In the case of highly activated reactor components, information could be provided to the authorities and operators if beside the direct segmentation after the extracting, a temporary storage could be considered as an ecological and economic alternative. With a possible temporary storage, both the volume of the active waste for the final storage could be reduced and valuable metals could be recycled. In addition, the radiation exposure for the dismantling personnel will be reduced.
In the case of concrete shielding, statements are made for single nuclides regarding their possible chemical mobility, which has a direct influence on the decommissioning strategy and final storage. In both cases, not only the absolute volume of the material but also the structural embedding of the radionuclides is important. This is decisive for the stability of the binding of the radionuclides in the concrete. The kinetics of possible dissolutions with transition into the liquid phase is thus influenced. Therefore, in addition to radiological, a physico-chemical characterization of important nuclides in the material will also be performed.