While, as has been seen above, in normal operation, deep disposal of nuclear wastes does not seem to represent significant potential problems for public health at any time in the future, the consequences of accidental situations must also, obviously, be examined. Let us assume that drilling occurs more than 500 years after the packages are installed, beyond a time during which memory and monitoring have been ensured. Drilling in such condi­tions could represent two hazards:

1. Radioactive elements brought to the surface along with the drilled samples; these elements do not, in principle, enter the food chain, but they can be responsible for external radiation.

2. If drilling is done to obtain drinking water, contamination can occur as the water percolates through the disposal site.