Abstract
In the Organization for Economic Co-operation and Development/Nuclear Energy Agency/Committee on Safety of Nuclear Installations (OECD/NEA/CSNI), the Preparatory Study on Analysis of Fuel debris (PreADES) project was recommended by the Senior Expert Group (SEG) on Safety Research Opportunities post-Fukushima (SAREF) as one of several appropriate “near-term projects” to contribute to further international efforts to understand the 1F accident and support decommissioning efforts. As a result of the activity for five years, the PreADES project has summarized collected knowledge and expertise concerning fuel debris characterization and identified needs for fuel debris analyses that would contribute to 1F decommissioning. The project also aimed to improve the understanding of severe accidents and reactor safety assessments as well as creating appropriate and optimal methodologies for future sampling, retrieval, and storage of fuel debris. Consequently, the project provided important input for future international projects.
The activity of the PreADES project was carried out under the collaboration with many international organizations, and accumulated useful expertise. Following project tasks were discussed: 1) the Characteristic table that clarified characteristics of fuel debris for 1F, Three Mile Island Unit 2, and Chernobyl Nuclear Power Plant Unit 4 from various analyses and experiments, 2) Compiling informative tables for fuel debris analysis (the Analytical table, the Major issue and methodology table; the Hot testing analysis capabilities table). The first one identified analysis data to be obtained, and the last one indicated practical appropriate and optimal methodologies for fuel debris handling, 3) future international R&D framework.
Through these activities with many discussions, project partners re-realized that important aspects for the success of future collaborative initiative was to implement conditions for fluid dialogue and information exchange between involved organizations. As these organizations may have different priorities, such as interests in severe accident analyses or promotion of the decommissioning, it is important that information exchanges are established. It is only with such a constant open dialogue that more focused guidance and recommendations for the completion of debris retrieval.
Currently, post-PreADES project, “Fukushima Daiichi Nuclear Power Station Accident Information Collection and Evaluation (FACE)” project has been launched. In the project, actual sample analyses and international round-robin analysis activity with debris simulants are being discussed continuously.
