Initial nuclear state characterization in view of decommissioning STRATEGIST, a data analysis & sampling design web tool

The INSIDER project (2017-2021, (LGI, 2017)) developed and validated a new and improved integrated characterisation methodology and strategy during nuclear decommissioning and dismantling operations (D&D) of nuclear power plants, post-accidental land remediation or nuclear facilities under constrained environments. One of the important outcomes of this strategy development is a statistical approach guideline, that is transformed into a web tool, which serves as a more user-friendly interactive interface. The web tool, named STRATEGIST (Sampling Toolbox for Radiological Assessment To Enable Geostatistical and statistical Implementation with a Smart Tactic), intends to guide the expert in handling the problem definition and applying a strategy based on proper data analysis and sampling design. It is not meant to provide the nonspecialist with a comprehensive mode of operation for the complete process of initial nuclear state characterisation in view of decommissioning. This paper describes the approach followed to develop the guideline and STRATEGIST web tool, based on state-of-the art statistical techniques for preliminary analysis and data processing. Furthermore, it briefly outlines the web tool contents and structure. The initial guidance was adjusted and finalized, based on its implementation into four different use cases, which are concisely summarized as well. Lessons learnt from this implementation are listed in terms of overall strategy implementation, selection of sampling approaches and data analysis methods and are complemented with a specific focus on uncertainties. They illustrate that the implementation of a proper data analysis and sampling design strategy simplifies and optimizes the decision making process concerning the selection of the different D&D scenario options.