私の尊敬する知人であり「共通目的」を持つ原発・核専門の教授の報告を参照：

The Human Consequences of the Fukushima Dai-ichi Nuclear Power Plant Accidents

September 21, 2015 Eiichiro Ochiai | PhD | Juniata College, PA | Department of Chemistry

When a very strong earthquake (magnitude 9.0) hit the Pacific ocean side of the northeastern part of the main island of Japan on March 11th (3.11) 2011, the accompanying huge tsunami wiped out many communities along the coast. Close to 20,000 people lost their lives, mainly due to the tsunami. Many who were stripped of their homes and livelihood continue to struggle to recover their ways of life.

One of the most disastrous results of the quake/tsunami was the devastation at the Fukushima Dai-ichi Nuclear Power Plant (Fk-1) of the Tokyo Electric Power Co (TEPCO). The plant is known in Japan as Fk-1 (Fuku-ichi). It released an enormous amount of radioactive material. Its effects on living organisms have already begun to be felt in many ways, though it’s been only four and a half year[s]. It may, however, be premature to make a judgment as to the degree of disaster, in light of the fact that the after-effects of the Chernobyl accident of 1986 are still unfolding.

This article discusses some prominent features of the current situation (as of August 2015) in the aftermath of the Fk-1 accident.

The Fukushima Nuclear Power Plant Accident

Four of the six reactors (units 1~4) on the premises of the Fk-1 plant experienced serious accidents including explosion, while the other two reactors (5 and 6) were not in operation and remained intact, as they are located slightly apart from the others.

Units 1~3 were operating at the time, but shut down automatically when the quake hit. The shutdown reactors need to be continuously cooled, because the fuel rods, though out of fission reaction, release great heat due to the nuclear decaying process of radioactive fission products. The quake caused substantial damage to the reactors, and the cooling systems of units 1~3 did not function properly due to both physical damage and human errors. As a result, the fuel rods in units 1~3 “melted down”.

Water added from outside for cooling purposes reacted with the hot rods to form hydrogen gas. The resulting hydrogen explosion in unit 1 stripped the roof on March 12th. Unit 2 showed no apparent damage, but released an enormous amount of radioactive material through holes created by the quake, mostly on March 15 and thereafter. The explosion at unit 3 on March 14 was most damaging. TEPCO insists that it was also a hydrogen explosion, but many observers offered different opinions, including one that it a small-scale nuclear fission explosion occurred. Unit 4 had no nuclear fuel rod in the reactor, though a large number of spent as well as new fuel rods were in its storage pool. It exploded also, its cause unknown, though TEPCO speculated that hydrogen gas entered from the adjacent unit 3, and exploded.

Release of Radioactive Material from Fk-1

A large amount of radioactive material was released as a result of the accidents. How did it happen? Leakage through cracks and holes made by the quake on some reactors, explosions, intentional vents to relieve pressure, and leakage of cooling water which is contaminated as a result of contact with the melt fuel rod debris.

The amount of radioactive material cannot be determined accurately, and can only be estimated by various means. TEPCO made an estimate of the released amounts of several tens of radioactive nuclides based on the readings of several monitoring posts placed on the premise 1. The initial governmental data 2 were based on these estimates. Some of the official data are presented in Table 1. The government’s assessment of the scale of the release from Fukushima, based on these data, was that the radiation release was relatively small compared to that of Chernobyl (April, 1986 in Ukraine), about one tenth to at most one third.

But these data accounted for only the release into the atmosphere. Radioactive materials were also released into the water systems surrounding the facilities, as well as directly into the ocean. When the amounts released into the water and the ocean were estimated 3, the total amounts released were re-calculated 4. They are shown in Table 1 along with the official data. The ratio of the amount released from Fukushima to that from Chernobyl ranges from 1.2 to 3.1 for the major nuclides, suggesting that the extent of radiation release from Fukushima was very likely more than that from Chernobyl; perhaps more than twice if all were taken account of.

Table 1. The amount of radioactive nuclides released from the Fk-1 accident (2011) compared with those released from the Chernobyl accident (1986)

Radioactive materials are still continuously coming out; and the data shown in the table do not take account of them. For example, Fig. 1 shows the radiation levels (Bq/L) of Cs-134, Cs-137, Sr-90, H-3 and all beta sources found in one of the drainage systems in the facility, which drained out into the ocean between April 2014 and Feb 2015 6. The amounts leaked out through drainage systems are given in Table 2 6. Substantial amounts continue to leak out. The main reason is that 300 tons of cooling water is being added daily to keep the fuel rod debris cold. That cooling water is immediately contaminated, and leaks out as a number of gaps/holes were created by the quake, though an effort has been made to contain and store it in tanks. Eventually TEPCO hopes to decontaminate the water collected, and return it to nature. How successfully decontamination procedures are being carried out is not known. There are other sources of water. One is subterranean water, which flows through the premises, particularly under the contaminated buildings. This has not yet been halted.

Fig. 1. Radioactivity of K-drain system in Fk-1 premises

Table 2 Leaked amount of radioactive material through drainage systems in Fk-1 premises

Are radioactive materials still leaking out into the atmosphere as well? No obvious phenomena, such as explosions, have been observed since March 2011, though sudden rises in temperature of the reactors have occurred occasionally. However, some signs of plumes are still often observed visually (as dense fog) as well as on the monitoring posts placed all over Fukushima prefecture and throughout Japan. Monitoring post data are daily posted on the internet 7. Occasionally sudden peaks (spikes) appear on a number of posts, near and far. If time sequences are carefully taken account of, it seems, they could show the flow of a plume. Such a plume flow was seen throughout Japan on April 14, 2015. Spike phenomena occurred on April 8/9 and May 16, 2015, as well. Fig. 2 shows an example of a spike phenomenon on April 9 in Iidate-mura 30 km northwest of Fk-1. This is not a complete record; it is only what this writer observed in periodic checks.

Fig. 2. Spikes observed in a monitoring post in Iidate-mura, Fukushima

Each time there are spikes on monitors, the government attributes such a phenomenon to a “malfunctioning monitor”, and shuts down such posts, until the readings return to normal (regular) levels. It is rather strange that a number of monitoring posts (all across Japan) go out of order simultaneously or rather in sequence. This phenomenon indicates that sudden releases of radiation are still happening occasionally, but how often, on what scale, and their causes are not known.

All these events suggest that the accidents are “far from contained”, and radioactive materials are still leaking out. In sum, the overall radioactive materials released from the Fk-1 accidents are already larger than that of Chernobyl and will increase further unless measures are taken to stop these leakages.

Distribution of Radiation Levels

How far and how widely the radioactive materials are dispersed, i.e., the radiation levels at various locations, are constantly monitored not only by officials as mentioned above, but also by civil activists. Unfortunately the official data may not be reliable, as many observers have noticed. Civil activists have compared the monitoring values with their own readings and found the monitor readings lower by as much as 50% at many locations. The structure of the monitor itself often prevents the true reading of radiation. It has been pointed out, for example, that a metal plate placed just under the measuring device shields radiation coming from below 8.

A monitor placed by the government reads the so-called spatial dose; i.e., the supposed external exposure dose at 1 meter above the ground. The radioactivity is measured in terms of Bq and, if equipped, the energy value of the radiation measures is combined to indicate the spatial dose value, expressed often in terms of μSv/hr. Most monitors can measure only γ-radiation, and many monitors as well as Geiger counter type instruments measure only cpm (counts per minute), convert it to Bq values, which are converted to Sv values assuming that radiation is due to cesium (Cs-137). Cs-137 has a relatively long half-life of 30 years and is produced in a significant quantity in the fission reaction. The spatial dose is due to many other nuclides such as strontium (Sr)-89/90, tritium (H-3) and iodine (I)-129/131, but the contribution from these and other nuclides is not taken account of, or rather is counted as Cs-137. It is a sort of measure of radiation level, but does not represent the true exposure dose. However, this value is commonly used in assessing the danger level due to radiation.

A few readings will be cited here to illustrate the typical radiation levels given by the government. Some readings at monitoring posts on March 31, 2015 were: 6~10.5 μSv/hr in Hutaba-cho where Fk-1 is located, 4~17 mSv/h in Okuma-cho, just south of Hutaba (several km from Fk-1) and 1.7~3.6 μSv/hr in Tomioka-cho, south of Okuma (i.e, 10 km south of Fk-1). These are readings in highly contaminated areas.

On April 14, 2015 when a plume seemed to have been released, several readings (except the spike, which was a sudden rise to twice or higher level) were: 0.03~0.04 μSv/hr in Hokkaido (northernmost island); 0.02~0.05 μSv/hr in Aomori; 0.02~0.05 μSv/hr in Iwate; 0.04~0.12 μSv/hr in Miyagi (just north of Fukushima); 0.14~0.30 μSv/hr in Soma city, Fukushima; 0.05~0.12 μSv/hr in Tochigi; 0.08~0.09 μSv/hr in Tokyo; 0.03~0.06 μSv/hr in Kyoto; 0.05~0.08 μSv/hr in Hiroshima; 0.04~0.06 μSv/hr in Fukuoka.

These are recorded on the monitoring posts, but many places are not covered by monitoring posts, where much higher radiation levels have been recorded; i.e., “hot spots”. Recently reported examples were: 1.23 μSv/hr in western Tokyo on July 23, 2.92 μSv/hr in Saitama on July 25, 4.8 μSv/hr in Iwaki (30 km south of Fk-1) on Aug. 2 9.

Let’s assume that you are standing on a location where the monitoring post showed 0.1 μSv/hr throughout a whole year. Then, you will be exposed to 0.9 mSv/year (0.1 μSv/hr x 24 hrs x 365 days=876 mSv/year=0.9 mSv/y). The Japanese government calculates the dose per year by assuming that one would stay in open areas for 8 hrs and for the rest of the day in buildings, where the radiation level is assumed to be about 40% of the outside. This calculation would make the exposure dose significantly lower than the real value; in the example above, it would be 0.54 mSv/year. This assumption is arbitrary, indeed, the inside of a building has often been found to have radiation levels as high as that of the immediate outside.

The official exposure dose allowed is currently set as 1 mSv/year (see note at the end). This corresponds to a dose rate of 0.18 μSv/hr according to the governmental way of calculation. It is further degraded to 0.23 μSv/hr with some other arbitrary assumptions, and this value is regarded as the permissible level of dose rate. So dose rate below this value is supposed to be OK. If you are exposed directly to this level for a year, then your accumulated dose will be 2 mSv/year. In other words, the government limit of 1 mSv/year is actually close to 2 mSv/year in reality. The government is currently trying to raise the 1mSv/year limit to 20 mSv/year. If 20 mSv/year is approved and people are forced to return to their previous homes under this condition, they will be exposed to dangerously high levels of radiation. It must be pointed out, though, that there is no safe level.

Radioactive iodine affects the thyroid immediately. Iodine-131 is short-lived with a half-life of 8 days, and I-129 has a very long half-life of 15.7 million years. Both would be readily absorbed into the thyroid gland, as iodine is used to make thyroid hormones. In the nuclear reactor, both are produced in comparable amounts, but I-131 affects the thyroid more seriously. An entity with a shorter half-life emits radiation more often than that with a longer half-life in the same chemical quantity. The distribution of I-131 in the environment is difficult to determine accurately, as it is short-lived.

In Dec. 2014, the official nuclear regulatory committee (Japan) published a report to indicate that Fk-1 is still emitting I-131 and other I-radioisotopes 10. According to their report, trans-uranium Cm-242 and other such nuclides were formed in the fuel rods during the operation, and they fission spontaneously, as a result producing radioactive nuclides including I-131. The possible maximum amount of I-radioisotopes released from this source has been estimated as 28 mSv/week (=170 μSv/hr) in terms of equivalent dose for child thyroid at the border of the premises of Fk-1 10.

An alternative expression of contamination is the radioactivity of soil, typically Bq value per kg of soil, which often is converted to Bq/m2. It is assumed that the density of soil is 1.3 g/cm3 and that the radioactive material exists in the uppermost 5 cm of the soil, so that Bq/m2 value is 65 x the value in Bq/kg. This value (Bq/kg) is real, measured directly by an instrument on a sample of soil. Hence this may be more reliable in expressing the level of contamination than the spatial exposure dose. Besides, the source of radiation (from a soil sample) can be readily identified. This is not sufficient, however, as minute radioactive particles can be floating above the soil, which can be measured as spatial radiation.

In all these expressions, a fundamental uncertainty is that radiation levels may not be constant over time. Radioactive material decays over time and can move due to water flow or wind. Therefore, radiation levels have to be monitored continuously.

It must be pointed out that the external exposure dose level obtained from measurements of this kind (i.e., spatial dose and soil contamination) is less important than the internal exposure dose, which is not necessarily related to the external dose. The significance of internal exposure will be outlined below. The only thing that can be said here is that people living in a place of higher spatial dose level and/or higher soil contamination would have a higher risk of being exposed internally; but there is no proven direct correlation, and cannot be.

The more serious factor, internal exposure, is supposed to be measured by the whole body counter. But it can measure only g-radiation, and cannot measure the more serious a- and b-radiation. Besides, it measures only the radiation coming out of a body at the time of the test, and cannot determine the more meaningful accumulated exposure dose. Hence whole body counter results can only be used to give a tested person mental relief in cases where the reading is low or non-detectable. But, even that could be dangerous, if the source inside is emitting a and/or b radiation.

Reality of Internal Exposure

The effects of radioactive fallout from an accident of a nuclear power reactor as well as a nuclear bomb explosion are caused mostly by “internal exposure”, yet no adequate attention has been given to this aspect by the authorities and the associated scientists. The sources of the internal exposure are minute radioactive particles floating in the air, which can be inhaled, and contaminated food and drinks consumed. Radioactivity of foods and drinks produced in the contaminated area is monitored, and those with activity higher than the regulation values cannot legally be marketed.

One cannot well safeguard against ingesting radioactive material, unless one measures the radioactivity of everything one takes in, which is not possible. The issue of “internal exposure” is complicated, and would require another detailed article. For now, three photographs are shown below to illustrate the reality of internal exposure.

Figs. 3 and 4 are the trace of a-particles in the preserved tissues of victims of the atomic bomb explosions in Hiroshima and Nagasaki. It is not easy technically to take this kind of photo, and scientists succeeded in doing so only recently (11, 12). The source of the first trace is plutonium from the Nagasaki bomb, and that of the second is uranium from the Hiroshima bomb. The plutonium and uranium embedded in the tissues of atomic bomb victims are still emitting a-radiation after 70 years. This says that the fallout of the atomic bomb explosions, which included uranium in the Hiroshima bomb and plutonium in the Nagasaki bomb, somehow got into the body of the victims and stuck in those tissues, and emitted and destroyed the surrounding tissues for 70 years. Both plutonium and uranium have a long half-life, millions of years or more.

Fig. 3. a-Particles travel straight even in tissues. The linear traces are those emitted by plutonium in the preserved kidney tissues of an A-bomb victim in Nagasaki (70 years ago) 11 Fig. 4. A trace of a-particle of uranium in the lung tissue of a Hiroshima victim 12 Fig. 5. The heart muscle fibers are broken in the heart of a man (43 years old) who died of heart disease in the most contaminated area (Belarus) of the Chernobyl accident 13

Fig. 5 shows the heart muscle fibers of a victim of the Chernobyl accident 13. They are broken at many places. Likely the b and g radiation from Cs-137 (and others) damaged the fibers by breaking the chemical bonds. The traces of b and g cannot be visualized in such samples.

Thyroid Cancers among Children in Fukushima

The authorities, such as ICRP and IAEA, have acknowledged that thyroid cancers in children can be caused by radiation, likely due to I-131. They have also recognized the causal relationship between leukemia and radiation. But they deny a causal relationship in the case of other cancers and other diseases, despite the fact that many studies and reports have shown that all sorts of disease including cancers can be caused by radiation.

Eiichiro Ochiai was born in Japan, and educated up to the PhD in Japan. He taught and conducted research in chemistry at college/universities in Japan, the United States, Canada and Sweden. Publications include “Bioinorganic Chemistry, an Introduction” (Allyn and Bacon, 1977), “Bioinorganic Chemistry, a Survey” (Elsevier, 2008), “Chemicals for Life and Living” (Springer Verlag, 2011), and “A Sustainable Human Civilization Beyond ‘Occupy’ Movements” (Kindle, 2011). His recent publications in Japanese include Hōshanō to jintai (Radioactivity and human beings; Blue Backs, 2014); Hōshanō wa jinrui o horobosu (Radioactivity will destroy humanity, Ryokufū Shuppan, 2016).