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.

LTD Phase 1
Start of radionuclide injection on 7th June, 2007

November 2009

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

Overcoring of LTD monopole
Figure 1: Overcoring of LTD monopoleLTD overcore prior to subsampling
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.

Diffusion profiles in Grimsel granite
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 Diffusion - Long Term Diffusion project (LTD)

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.