6.17. The impact of any modifications to the design that have been implemented during the excavation and/or construction period should be considered in the safety case and associated safety assessment. This process should be supported by the following:@@- An update of the level of knowledge on the ability of each component of the disposal system to fulfil its expected role under the normal evolution of the facility and under disturbing events, both anticipated events and less likely events. This should include a full scale characterization of the site, the maximum waste inventory for the facility, including radiological characteristics and other properties of the waste, presentation and explanation of design features, where appropriate supported by tests, and demonstrations of prototypes of critical components identified.@@- The choice of construction techniques and their validation, i.e. demonstration that these technique(s) preserve the containment and isolation properties of the natural barriers to the extent necessary.@@- An identification of areas where uncertainties important to safety still exist, which will have to be managed as part of the demonstration of safety.