Requirement 11 of SSR-5 (Ref. [1]): Step by step development and evaluation of disposal facilities
Disposal facilities for radioactive waste shall be developed, operated and closed in a series of steps. Each of these steps shall be supported, as necessary, by iterative evaluations of the site, of the options for design, construction, operation and management, and of the performance and safety of the disposal system.
6.1.
The development of a geological disposal facility can take decades. The goal of assessing safety at key decision points in the development process, prior to commitment of additional resources, makes it practical to divide the programme into a series of steps. Typical steps should be set at regulatory or governmental decision points for the approval of construction of a geological disposal facility (construction), the approval to receive and emplace waste and the approval to close the facility permanently (closure). At each of these steps, the safety case is required to be updated [1]. Such an approach provides multiple opportunities to assess the quality of the technical programme and the safety case supporting the decision making process and thus provides confidence in these. Confidence in the safety and feasibility of a geological disposal facility is enhanced through the step by step process and by the maturing safety studies as the project progresses. Figure 1 illustrates a development timeline for a disposal facility, including specification of decision points and phases of activities.
6.2.
Key programmes (e.g. site characterization, design activities, accounting for, and control of, nuclear material and environmental monitoring, safety assessment) will be ongoing over a number of steps in the development of the disposal facility (see Fig. 1). As information matures and evolves with the safety case, design and site characterization, information from these key programmes should be shared among other relevant programmes (e.g. the safety case should inform the site characterization and design programmes of the relevance of uncertainties; performance monitoring should be used to provide confirmation of assumptions made in the safety case). The step by step process is an iterative process that should maximize the value of information as it evolves over the series of steps.
6.3.
Additional steps may be introduced to facilitate the project management of facility design, commissioning, waste acceptance and operation, and post-closure elements, and may serve as supplementary points for review of the safety case or supporting safety assessments. The nature of the reviews will depend on national practices and the facility in question.