In future stages of the disposal programme, the main drivers of the RD&D programme will be the need for optimisation, which must be carried out from the perspective of safety (the updating of the safety cases at each milestone), feasibility of implementation (confidence underpinning the feasibility of implementing the design at each milestone) and resources (assessing cost efficiency up to completion). In anticipation of the construction and operating licences, technological developments are also foreseen. These technological developments will affect all barrier components as well as their implementation.