New map of radioactive iodine released from Fukushima Daiichi

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The American Health Physics Society released a map which shows how far radioactive iodine spread in the wake of the Fukushima Daiichi nuclear disaster.  The map was generated by researchers from the Japan Atomic Energy Agency and the United States Department of Energy after they analyzed radiation data that had been gathered jointly between April 2nd and 3rd of 2011.

The map records levels of iodine-131 which contaminated the soil after escaping from the damaged reactors at the Fukushima Daiichi nuclear power plant which were recorded from aerial radiation surveys conducted nearly 1,000 feet above the ground.

The distribution pattern was similar to that observed with radioactive cesium, but the problem is that iodine has a half-life of only 8 days, an extremely short period which makes it impossible to determine how much was leaked and how far the materials spread.  The map shows that the majority of radioactive materials which escaped from the reactors spread around the nuclear power plant with the largest doses extending to the northwest.

The map does show that iodine levels over 3,000,000 becquerels per square meter were detected over 20 kilometers away from the nuclear power plant.  It is expected that researchers in Japan will used to estimate the amount of iodine received by residents’ thyroid glands.

Source: JAEA

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  1. Monitored from airplane would only be an average of a large area, I would think some areas are 10+ times the measured amount.

  2. This only shows the area measured by a monitoring aircraft. It does NOT show how far the contaminated material spread. The estimates will be wrong, and there will be more people who will come up sick than will be predicted.

  3. Convenient that the map stops shy of the city of Fukushima, which probably got at least 300,000 Bq of radioiodine. Also, these measurements were taken 22 days after the accident! The article doesn’t state if these contamination levels were what was found or what was reconstructed based upon the I131 half-life.

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