Quintessa

Long-Term Cement Studies Meeting in Henley-on-Thames

Quintessa recently hosted the biannual meeting for the Long-Term Cement Studies (LCS) project at Leander Club in Henley-on-Thames.  This international project is a collaboration between Nagra (Switzerland; the project leaders), JAEA (Japan), Posiva (Finland), RWM (UK) and SKB (Sweden), and seeks to extend our understanding of cement and cementitious systems in the context of geological disposal of radioactive waste.

The historic Leander Club, one of the oldest rowing clubs in the world, provided a comfortable backdrop to the technical discussions at the meeting.  The main focus of the LCS project is an in situ experiment at the Grimsel Test Site, where a solid cement source has been inserted into a borehole intersecting a natural fracture in the crystalline rock.  Two other boreholes, situated a short distance away and intersecting the same fracture, are used to monitor the hyperalkaline plume produced as the cement degrades in the presence of the natural groundwater.  The experiment, which was emplaced in 2009, is due to be overcored later in 2015, at which point analysis will be undertaken to determine the extent and type of mineralogical alteration in the cement and surrounding rock.

Quintessa (on behalf of RWM), along with the other modelling teams involved in the LCS project, are currently simulating the in situ experiment in order to test the predictive power of numerical and conceptual models of such systems.  The results from each of the modelling teams were presented and discussed at the meeting.  Challenges include the representation of the flow within the fracture and the wider system of interconnected fractured rock, which is likely to follow channelled flow paths.  The model results, along with data collected from the experiment, will inform waste management organisations on how cement structures are likely to behave in the geological disposal environment, and indicate the impact that the hyperalkaline plume may have on the surrounding rock and flow paths.

LCS meeting