Keywords:Fukushima Daiichi NPP accident, Fuel debris retrieval, Sample analysis, Representativeness of samples, Inhomogeneity of fuel debris
Based on the analysis of the samples collected in the PCV interior of Fukushima Daiichi NPP, potential issues regarding the fuel debris retrieval are summarized. The analytical targets, analytical method and obtainable knowledge that are necessary to evaluate each issue are discussed. Valuable information can be obtained even from small samples to understand the current situation of the plant and the accident progression. Although the amount of collectable samples is limited, we considered how to evaluate the whole fuel debris and how to utilize the analytical results for recriticality, burnup and safety treatment issues.