Long Term Diffusion (LTD) - Phase 1
Circulation of a cocktail of sorbing, weakly sorbing and non-sorbing radionuclides (3H, 22Na, 131I, 134Cs) in the monopole of WP-1 was started on 7th June, 2007.
Water samples retrieved twice a month and more frequently in the first two months were analysed at the Paul Scherrer Institute (PSI) to estimate the amount of sorption and diffusion with time.
Start of radionuclide injection on 7th June, 2007
Overcoring and subsampling of the LTD in-situ experiment
Overcoring and subsampling of the in-situ diffusion experiment of WP-1 after almost 800 days of continuous monitoring and circulation of radionuclides in a packed-off interval were successfully carried out in November 2009
Figure 1: Overcoring of LTD monopole
Figure 2: LTD overcore prior to subsampling
Detailed analyses of the subsamples from WP-1 are currently ongoing at HYRL in Finland and NRI in the Czech Republic. Preliminary results are shown in Figure 3.
Figure 3: Diffusion profiles in Grimsel granite based on preliminary analyses carried out by NRI after almost 800 days of circulation of H-3 (green), Na-22 (pink) and Cs-134 (blue).
The final results from the analyses of the subsamples will be used in post-mortem modelling exercises carried out by four teams later this year and compared with predictive models developed prior to circulation of the radionuclides in order to re-examine current diffusion models used in safety analysis and performance assessments.
Long Term Diffusion project (LTD) Experiment