FUKUSHIMA Lives on the Line

179chap.IVPatient Relief Activity Records [Essays and Research Publications]FUKUSHIMA: Lives on the Linedominantly emitted substances in Chernobyl, it is thought that this is the similar case in Fukushima. However, whereas only trace quantities of radioactive strontium and plutonium, which led to safety concerns regarding MOX fuel, were found outside the Fukushima nuclear power plants, a significant amount of those radioactive materials was released in Chernobyl. The emitted amount (approx. 520 TBq) in Chernobyl was approximately seven times more than that in Fukushima as of today even though these two accidents are in the level 7 of INES.Among the substances mentioned, radioiodine, especially iodine-131 is thought to be the one which most affected people's health around Chernobyl. Iodine 131 accumulated in thyroid glands particularly through food intake and resulted in internal exposure. Infants in Chernobyl also suffered internal exposure due to the intake of milk containing high density of iodine-131. Because the Soviet Union then did not control either food distribution or intake, people were unaware of ingesting contaminated milk, vegetables, water, etc. This was considered to be the main reason of internal exposure2).The most dominant nuclide emitted during the accident at the Fukushima Nuclear Power Plant was iodine-131. Another major component of the emissions was radioactive cesium (cesium-134 and cesium-137) , which has long half-life. Iodine-131 was detected in various produce including food, drink, and beef cattle immediately after the accident. Panic was caused not only through the reality of the accident but also by the widespread of groundless rumors through media and the Internet. As a countermeasure, the Japanese government specified values of radioiodine and cesium contained in food and drink as the provisional standard. They regulated shipping produce with higher content of radioiodine and cesium in order to prevent people from ingesting contaminated foods and drinks. We must remember the tough decision taken by the people working in the primary sector of industry in Fukushima Prefecture. Without this sacrifice, the chance of internal exposure to contaminated food could not be decreased. This countermeasure was taken based on the experiences of internal exposure in Chernobyl described above. Careful health evaluation is still required from now on , however, we assume the impact on people's health that we will see in the future will be far different from those in Chernobyl even though the accident was categorized in the same level seven.Table 1. Radionuclide emitted in the accident at the Chernobyl Nuclear Power Plant (Modified the data in Reference 1)RadionuclideHalf-lifeRadiationEmission amount (PBq)*Neptunium 23958 hrsβ-rays, γ-rays95molybdenum 9967 hrsβ-rays, γ-rays>168tellurium 13278 hrsβ-rays, y-nys1,150xenon 1335 daysβ-rays, γ-rays6,500iodine 1318 daysβ-rays, γ-rays1,760barium 14013 daysβ-nys, γ-rays240cerium 14133 daysβ-ays, γ-rays196ruthenium 10340 daysβ-rays, γ-rays>168strontium 8952 daysβ-rayszirconium 9565 daysβ-nys, γ-rays196curium242163 daysα-rayscerium 144285 daysβ-rays, γ-rays116ruthenium 1061 yearβ-rays, γ-rays>73cesium 1342 yearsβ-raysplutonium 24113 yearsβ-raysstrontium 9028 yearsβ-rayscesium 13730 yearsβ-rays, γ-rays85plutonium 23886 yearsα-raysplutonium 2406, 850 yearsα-rays, γ-rays0.042plutonium 23924,400 yearsα-rays, γ-rays0.030 *PBq is equivalent to 1015 becquerel.