On the adequacy of the format proposed to communicate risk and uncertainty. Deliverable D17

A template was developed in the first part of the ARGONA project to communicate the risk associated to a SNF/HLW repository. As a result of two sets of meetings, the format has evolved into two different formats. The first format has been designed to address an audience composed of people with a good education level (good background in mathematics), while the second one addresses a generic audience containing lay stakeholders. Both formats are implemented as verbal presentations supported by a PowerPoint file containing graphic supporting material and include the following sections: - the concept of risk and its steering role to assess repository safety, - what is a repository and how it works (small differences between formats 1 and 2 in the level of detail), - regulatory limits, - uncertainty sources and the way to tackle them, and - key results from a Safety Case/Safety Assessment to communicate (two different levels of communication of results, which make the most important difference between formats 1 and 2). The preferred output variable to communicate risk is the peak total dose and the preferred graphic representation is the boxplot. The selection of this output variable is a conservative option that reports the worst situation in each Monte Carlo simulation which, additionally, avoids the introduction of time in the results to communicate. The boxplot has been selected because of its easy interpretation and its suitability to facilitate the comparison of results from different scenarios