Risk Factors Selection Approach for Nuclear Decommissioning Risk Assessment, Modeling, and Management

Due to the complexity of nuclear decommissioning projects, developing a risk assessment model to manage the project risk is paramount. The current study is an attempt to identify all the possible risk factors that can arise in a nuclear decommissioning project. A literature review and the expert judgement method were used to identify and analyse all the possible risk factors. The identified factors are then further refined, and the most important risk factors are selected to be included in the final risk assessment model. This work presents the criteria developed for the simplification, refinement, and assessment of risk factors. The criteria used considered the availability of data, the clarity, and the measurability of the selected factors. Risk factors with a lower rating are eliminated, and those with a similar focus of attention are grouped, enabling the selection of a simplified final list of risk factors for the model. This work also proposed a method of assessment for the remaining factors to allow the quantification of individual risk factors within the model. From the 81 risk factors initially identified, 18 consolidated factors are considered for the development of the risk assessment model. The selection process and risk rating approach presented in this work serves as a critical foundation for the development of a robust nuclear decommissioning risk assessment and management.

Status of research and development conducted by the International Research Institute for Nuclear Decommissioning

Since the International Research Institute for Nuclear Decommissioning (IRID) was established as a technology research association in August 2013, it has been engaged in research and development (R&D) for decommissioning the Fukushima Daiichi nuclear power plant, which is currently an urgent issue, to strengthen the platform for decommissioning technology for the future. The work of IRID R&D is classified into three main pillars: removal of spent nuclear fuel from the pool; retrieval of fuel debris; and technological development for treatment and disposal of solid radioactive waste. This article describes an overview of R&D as of the first half of the fiscal year 2020, mainly focusing on investigation inside primary containment vessels and retrieval of fuel debris.