6.10. At the stage of site investigation and selection, the basic site characteristics should be described in such a way that they show how the safety function of each natural and engineered component within the proposed design options will be achieved for the site(s) under consideration. This description should be supported by the following:@@- An overview of the level of knowledge about the ability of each component of the disposal system to fulfil its expected role, including under disturbing events identified as possible perturbations;@@- A research and development programme to verify the expected properties of the site determined at the stage of concept development; for programmes to develop a disposal facility for high level waste, this may include the development and operation of an underground research laboratory;@@- An assessment of the capacity of the site and its ability to accommodate existing waste streams and those expected in the future;@@- A preliminary assessment that, inter alia, identifies the perturbations that each component and the whole facility may undergo, both of internal origin (e.g. thermal, chemical, mechanical, radiological or reactivity changes) and of external origin (e.g. intrusion, climate change, seismicity);@@- An investigation of the favourable behaviour of component materials (generally metal, clay and concrete) necessary for the safety of the disposal facility;@@- Proposals on how the technical feasibility of the disposal system will be demonstrated through appropriate qualification and performance confirmation programmes;@@- A demonstration that at least one design option presents good prospects of feasibility, in the sense that it relies on proven and/or easily demonstrable features and is able to accommodate uncertainties relating to the expected performances of the various components of the disposal system;@@- Consideration, again, of how the components of the disposal system will function together in a complementary manner to ensure that there is adequate defence in depth, including an extensive confirmation of the overall compatibility of the system components;@@- An identification of areas where uncertainties important to safety could exist, which will have to be managed as part of the demonstration of safety.