Radioactivity and Air Dose Rate
（2015）
ＱWhere were radioactive materials deposited and in what quantities?
ＡIt was confirmed that radioactive iodine and tellurium deposited as well as cesium just after the accident. But now, radiation exposures are mainly caused by radioactive cesium.
- Radioactive nuclides that were confirmed to be deposited in many places by the accident were cesium (134Cs and 137Cs), iodine (131I), tellurium(129mTe), silver (110mAg), plutonium (238Pu, 239+240Pd and 241Pu), and strontium (89Sr and 90Sr).
- Radioactive cesium deposited across a wide region of east Japan.
- The amount of radioactive strontium and plutonium deposited in soil was within the range of levels that existed before the accident.
- Radiation exposures were estimated based on measurement data. Long-term radiation exposures will mainly be caused by radioactive cesium, while the contribution of plutonium and strontium to radiation doses is expected to be low.
Fig.1 Maps of deposited radionuclides estimated by analyzing soil samples (June, 2011)
（Cited from the Report on Investigation of Radiation Distribution：
http://radioactivity.nsr.go.jp/ja/contents/6000/5235/24/5253_20120615_1_rev20130701.pdf,
http://radioactivity.nsr.go.jp/ja/list/504/list-1.html）
Fig.2 Cs-137 deposited amount evaluated by United Nations Scientific Committee on the Effects of Atomic RadiationUnited Nations Scientific Committee on the Effects of Atomic Radiation (Report by UNSCEAE, 2013)
(http://www.unscear.org/docs/reports/2013/13-85418_Report_2013_Annex_A.pdf)