| Rock Type | Advantages | Disadvantages |
| Crystalline (e.g., Granite) |
- High mechanical strength
- High thermal stability
- Often resistant to chemical change
- May retard radionuclide transport
|
- May be highly permeable and porous
- Brittle under tensional stress
- Numerous fractures and joints
- Often complex geology
|
| Clay |
- Low permeability
- Plastic (self-sealing) movement
- Few fractures
- May retard radionuclide transport
- Easy to excavate
|
- Most suitable clays are near the surface
- Adjacent sediments provide pathways
- May be hydrocarbon source rocks
|
| Salt |
- Low Permeability
- Dry
- Plastic (self-sealing) movement
- Few (if any) long-lived fractures
- High thermal stability
- High thermal conductivity
- Easy to excavate
|
- May contain corrosive brines
- May be an economic resource
- Salt formation may be mobile
- Accidental flooding could remove all salt
|
Reprinted with permission from Radioactive Waste
- Where Next? (London: Parliamentary Office of Science and Technology, November
1997), p. 77.
Institute for Energy and
Environmental Research