(GRS-586) Solubility Limits of Fission and Activation Products in Saline near Field Solutions

S. Hagemann, T. Meyer, H. Mönig, B. Bischofer, K. Jantschik

Funding code 02E11365

Event sequences in the repository system that lead to a contact of solutions with the stored waste containers can lead to a situation where a safe isolation of the radionuclides present in the waste in the containment-effective rock area can no longer be assumed. This can occur if the containers fail for mechanical reasons or due to corrosion, i.e., if they become leaky, so that intruding solution penetrates to the waste and mobilizes the waste materials from their matrix. According to the current state of knowledge, such developments of the repository system are to be expected in a clay formation even with consistent implementation of the safety concept for a repository. In order to evaluate these event sequences, long-term safety-analytical model calculations must be carried out.

The discharge of radionuclides from the near field is often determined by solubility limits3. However, solubility limits are not rigid quantities, but depend strongly on the local chemical environment (e.g., salinity, pH, redox level). In probabilistic long-term safety analyses, the uncertainties regarding the chemical environment are usually represented by ranges of solubility limits.