ANNALS ANNALES - Academia Oamenilor de Stiinta din Romania

Mărgărit Pavelescu, Alexandru Octavian Pavelescu, Ioan Ursu 50
The suggested approach was to identify the characteristics of the IRC of a type of a
high isolation site -HIS- that would be intrinsically safe and to then look for its
characteristics signature worldwide (McCombie , 2001).
3. IDEAL REPOSITORY CONCEPT
There is one way to substitute the sophisticated engineered barriers, namely to take
into account a site with simple geological structure and minimal groundwater
movement. Indeed, in this case the geological conditions in these regions would give
high assurance that the wastes are isolated from the environment and provide the
main component of a safety case, thus avoiding the requirement for complex
engineered solutions.
Therefore, in such cases it is much easier and not consuming time to fully
characterize the site. The following characteristics of the IRC might be identified:
1) simple and stable geology;
2) arid climate stable over hundreds of thousands of years with minimal
infiltration water to the rock;
3) minimal movements of groundwater and no direct groundwater pathways from
the repository level to the surface;
4) absence of ice cover in recent or future glaciating;
5) extremely low recorded seismic activity and negligible uplift or erosion rates;
6) low population density;
7) absence of significant of mineral or water resources;
8) minimal potential for inadvertent future human intrusion.
The performance assessment of the IRC may be much simpler that of the CRC. This
is because much of the safety case for high isolation site which is IRC will consists of
demonstrating that the conventional processes of transport by moving groundwater,
which must be quantified at conventional sites, will not significantly affect the performance
of the IRC.
The demonstration will be based on quantitative interpretations of the measured data
sets, but also on the consideration of the fundamental physics and chemistry of
transport processes and on direct determination of the age of the site groundwater.
Fundamental characteristics of high isolation site -HIS- that will simplify the safety
assessment are the spatial homogeneity resulting from the simpler geological
structure and their extrapolation in time resulting from the geological stability.
However, there will be important technical issues to resolve.
One is that at IRC the impacts of the repository itself cannot initiate any significant
transport of radioactive waste. The repository generates heat for the first few
thousand years and it will have to demonstrate that this heat will not cause damage
to any of the barriers, nor cause groundwater convections cells, which could
transport radioactivity to the biosphere.
Finally, another great advantage of the IRC is the retreavability. This implies
implementing a repository that allows for the possibility that a future society might
want to recover the disposed wastes.
One possible explanation for such an intention could be, for instance, to recover the
unburned energy in once through nuclear power systems where less than 10% of the
potential energy is extracted from the fuel.