The objectives of the work are to quantify the extent to which bulk water movement through a layered volcanic sequence at Sellafield (the Borrowdale Volcanic Group) occurs through small fractures amenable to a statistical description. In addition, the work will assess the feasibility of obtaining individual fracture flow data by the techniques developed by Nirex at its research site (Reskajeage Quarry, Cornwall, SW England). An assessment will be made of the use and application of the techniques within the site investigation programme at Sellafield.
1. Examination of geophysical and core logs to determine depths, orientations and average spacing of anticipated flowing fractures.
2. Initial double packer testing of borehole with a packer spacing less than average flowing fracture spacing.
3. Optimisation of packer spacing and test boundary conditions, based on initial observations.
4. Determination of distribution of fracture conductivities.
5. Input to stochastic discrete fracture network code and consequent predictions of flow over long lengths of borehole.
6. Comparison with measurements of flow over long lengths of the borehole.