6.77. If retrievability of waste is a design option, the safety case should address administrative and technical arrangements that ensure that: an appropriate level of technical ability to retrieve waste is maintained at each stage following emplacement of the waste; the methods for retrieval are specified; and periodic evaluations are made of the appropriateness and necessity of proceeding with the next step towards closure of the facility, maintaining the facility at the current step, or reversing a step, including retrieval of the waste if necessary. The safety case should further address monitoring provisions to verify that the conditions under which retrieval could be performed safely prevail.