The calculated activities of 90-Sr in water, bottom sediment and marine biota are in good agreement with measurements made in the coastal area around Fukushima before the accident. Fewer direct measurements of 90-Sr exist compared to Cs isotopes because the analysis of 90-Sr requires significantly more sample processing and handling to separate it from other beta-emitters. For this reason the model assumes that 90-Sr releases from Fukushima to the ocean are related to 137-Cs releases in ratios determined by direct measurement after the disaster. While releases are ongoing the model determined that the activities in sediments and marine foodstuffs depend primarily on the initial releases in March and April 2011 when rates of release were greatest. Using a conservative estimated release of 640 TBq (TBq = 10^12 Bq) the model predicts the following individual dose rates to Japanese consumers of sea organisms where the average consumer eats 23.4 kg of fish, 2 kg of crustaceans, 1.3 kg molluscs and 3.7 kg of macroalgae per year. It was also assumed that 50% of the fish consumed included the organisms bones.
Source: Daily Kos