(GRS 314) Uncertainty and Sensitivity Analysis of the SF Source Term of I-129 in the MELODIE Model using SUSA

G. Bracke, S. Hotzel, G. Mathieu

The uncertainty and sensitivity of spent fuel degradation models on the release of radionuclides is studied by GRS and IRSN in the following report. An important part is to correlate the uncertainties in the assumptions made for simulating the spent fuel degradation and the uncertainties in the associated release of radionuclides and to determine the sensitivity of the parameters by a probabilistic method. Sensitivity analysis was performed already using deterministic calculations in the french case /AND 05/.

GRS and IRSN have decided to model the concept based on the ANDRA's Carbon steel SF/Iron/Clay concept /NF 05/ as a test case. Spent fuel canisters are disposed of in horizontal tunnels closed by a bentonite plug. A bentonite buffer is placed around the canisters. Bentonite seals close the access drifts in order to limit the water flow in the repository. GRS/IRSN decided to use I-129 as an example for the release and transport.