6.65. As discussed above, the relevance of human intrusion scenarios for geological disposal facilities is limited, as the depth and location of such facilities makes it unlikely. The time frames of concern are also far too large to enable meaningful estimates of possible impacts from intrusion events to be made. Nevertheless, it may be decided to make an assessment of the consequences to demonstrate the robustness of the disposal system. The scenarios considered are speculative and somewhat arbitrary owing to uncertainties in the boundary conditions and other parameters, such as when it is assumed that the event will take place and what the state of the facility and its host environment will be at the time of intrusion. As a consequence, for geological disposal facilities, care should be taken when making quantitative use of the results obtained for human intrusion scenarios, in particular when comparing these to other scenarios (e.g. for purposes of optimization of protection and design). The most effective measures against inadvertent intrusion involve establishing the disposal facility in deep geological formations and providing knowledge maintenance in the long term.