Adaptive Staging is a cautious and deliberate decision-making and management process, fully consistent with good engineering practices. It emphasizes continuous learning, both technical and societal, includes scientific and managerial re-evaluations and reactions to new knowledge, is responsive to stakeholder input, and is designed to continually improve the project while retaining the option of reversibility.

When Adaptive Staging is employed, options for paths and end points remain open for as long as practical. Eventually, Linear and Adaptive approaches converge to an end. The final path, however, is usually not the one initially planned so that regulators, stakeholders, and the general public may perceive changes in the program as a reaction to some failure in the original plan. Adaptive Staging has the potential to reduce this perception by acknowledging remaining uncertainties and recognizing unexpected outcomes and occurrences as learning opportunities to improve the system.

Adaptive Staging is characterized by seven attributes. These are: commitment to systematic learning, flexibility, reversibility, auditability, transparency, integrity, and responsiveness. Taken separately, these attributes do not constitute the process that the committee calls Adaptive Staging; the simultaneous presence of these attributes makes the staging process truly Adaptive.2

The decision-making process separating stages is referred to as a “Decision Point.” A Decision Point is not just a “point” in time, but a process involving analyses, review, and evaluations, as well as the consequent decisions for future actions. Thus, at a Decision Point, the program implementer initiates a process that:

  1. systematically gathers, synthesizes, evaluates, and applies the information acquired to date;

  2. develops options for the next stage, including explicit consideration of reverting to an earlier stage;3

  3. evaluates and updates the assessment of the safety of the repository system, in light of the options;

  4. makes the findings publicly transparent and available;

  5. engages in dialogue with stakeholders;

  6. decides on the next stage based on all of the above; and

  7. disseminates decisions and their rationale.

In practice, the program implementer makes many more decisions than those at formal Decision Points. However, the more important or far-reaching the decision, the more the decision-making process resembles the Decision Point described above.

The main reason to plan these Decision Points throughout the program is to ensure that a series of relatively small decisions, each made on narrow criteria, does not lead the program onto an unsound path. Decision Points can also be introduced whenever new information warrants. Figures 2.1 a, b, and c illustrate schematically


The reader should not infer from this report that Linear Staging, by default, lacks all attributes of Adaptive Staging. A key difference between the two approaches is that Adaptive Staging is designed to fulfill all of these attributes, whereas that is not necessarily the case with Linear Staging.


Because reversibility is always an option, it is important that the repository program provide flexibility in its reference framework.

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