“There is a zero possibility of repeating in Japan the scenario from the Chernobyl nuclear power plant”

Japanese Nuclear Power and Wrath  of Nature

by Zbigniew Jaworowski, M.D., Ph.D., D. Sc.

Japan, perched on the so-called Pacific “Ring of Fire,” is one of the most seismically unstable countries. In the 20th Century, about 158,280 persons died there in nine major earthquakes, with Richter magnitude 6 and above. The Japanese had that in mind when building 55 nuclear reactors for 17 nuclear power plants, which supply the country with 34.5% of its electricity. They made them sturdy enough not to release any dangerous radioactivity outside the plant limits, even due to the worst earthquakes. The quake of March 11 2011, of magnitude 9.0, the greatest  in the Japan history, proved that the plants operated almost as expected. No dangerous radioactivity was reported to escape from the destroyed Fukushima nuclear power plants into the environment outside the plants’ limits, and nobody was seriously harmed by radiation among the public.

However, even though the power plants evidently withstood the 9.0 magnitude earthquake, they appeared to be sensitive to the enormous tsunami, with the waves up to 7 meters high, which flooded their emergency diesel power generators, intended to provide back-up power for the pumps that cooled the reactor core. This was evidently an effect of the poor original design of the 40-year-old power plant, as the generators were located just  behind a sea wall on low-lying coastal ground. The tsunami overwhelmed the 6-meter high barrier. The result was an overheating of the cores of the reactors. Like Chernobyl 25 years ago, Fukushima now brings important lessons for the only 56-years-old nuclear power.

In the heavily affected prefectures of Miyagi, Fukushima, and Ibaraki, there are 11 nuclear power reactors. Those which operated during the earthquake were automatically shut down when tremors started, and the crews started standard procedures of cooling the “residual heat,” i.e.,  pumping the water to the pressure vessels of the reactors. However, after an hour, the emergency power generators at Fukushima Daiichi plant were destroyed by the tsunami; the high pressure emergency cooling was lost, and before the mobile generators were supplied, the temperature of the core in the Unit 1 reactor increased  to a level where the zirconium cladding of the fuel rods reacted with water, producing hydrogen gas. When the gas was released from the pressure vessel on 12 March, outside the primary containment,  a hydrogen explosion occurred in the reactor building, outside the primary containment vessel, which remained intact. This technically aggravated situation injured several persons, but did not cause a large release of radioactivity to the environment. Cesium-137 and iodine-131 levels increased initially after the explosion, but these levels have been observed to lessen a few hours later.

On 14 March, this was repeated with an explosion at the Unit 3 reactor at the Fukushima Daiichi plant. The reactor building was destroyed, but again, the primary containment vessel remained intact and kept inside the  radioactivity released from reactor fuel. And on 15th March at 6 a.m. local time, a third hydrogen explosion occurred inside the plant’s Unit 2 reactor. Pressure readings indicated that the reactor’s containment vessel may have been damaged.

In addition to these three hydrogen explosions in four days, radiation has also spread into the atmosphere from the spent fuel pond at the Unit 4 reactor at this plant. A dose of up to 400 mSv per hour has been reported from a single location between reactor 3 and 4; later this  dropped to 11.9 mSv per hour, and after six hours, to 0.6 mSv. The fire was probably caused by a hydrogen explosion. As a precaution, the workers have been evacuated from the vicinity of this reactor. The fire was extinguished early on 15th March, and according to a spokesman for the Prime Minister, the fuel in the pond did not cause the fire.

All four reactors in the Fukushima Daini nuclear plant have now achieved cold shutdown, where coolant water is at less than 100oC, with full operation of the cooling system. Water levels are now stable in  all four reactors and offsite power is available. According to Metropolitan Government’s Office in Charge of Health and Safety the radiation readings in Tokyo were by 11 a.m. on 15 March 0.147 microSv, i.e. at natural level. This was in agreement with the data reported by American 7th Fleet operating in the Tokyo area showing very low levels of airborne radiation.

Precautionary Measures

Several precautionary measures were taken by the authorities. More important among them were evacuation of about 200,000 residents of ten towns near the affected nuclear plants, and  distribution of 230,000 units of stable iodine to evacuation centers from the area around the Fukushima Daiichi and Fukushima Daini nuclear power plants. The iodine has not been yet administered to residents, as this measure is not necessary.

The situation at the Fukushima nuclear plants is still unpredictable. However, one may imagine what would happen in the (rather improbable) case of  a total reactor meltdown of all  Fukushima Daiichi and Fukushima Daini power plants. We know what happened after a partial reactor meltdown in 1979 Three Mile Island event and a full meltdown in the 1986 Chernobyl catastrophe. In Japan, the result would be probably similar as in the Three Mile Island power plant accident, where the  reactor was protected by a thick concrete containment which efficiently retained fission products: There was almost no emission of radionuclides into the atmosphere, except innocuous radioactive noble gases, and practically zero radiation exposure of population.

There is a zero possibility of repeating in Japan the scenario from the Chernobyl nuclear power plant. The Chernobyl plant, an engineering pathology – a hybrid of a military plutonium factory and a power station, was not fitted with a containment vessel, and for ten days the radioactivity was freely escaping from the melted reactor, roasting in the burning graphite used for its construction. But even if by a magic miracle the containments of the Japanese plants perished completely in the quake or tsunami, the residents around them would not be harmed by radiation.

This is what we learned from the Chernobyl disaster, in which not a single person died among the affected  populations of Ukraine, Belarus, and Russia, as according to a recent report of United Nations Scientific Committee on the Effects of Atomic Radiation, a body most authoritative in radiation matters (UNSCEAR 2011), the radiation doses from Chernobyl fallout (of about 1 mSv per year) were below the natural radiation, too small to produce any effect. Even after ten times higher doses, the result would be the same.

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9 Responses to “There is a zero possibility of repeating in Japan the scenario from the Chernobyl nuclear power plant”

  1. etudiant says:

    With due respect, I believe this article is quite wrong.
    The site has six reactors with decades of spent fuel stored in cooling pools on the fifth floor of the reactor buildings and in a larger in ground pool.
    Four of the reactor buildings have been damaged or destroyed by hydrogen explosions arising out of water decomposition from overheating exposed fuel rods, fresh or spent.
    The overheating fuel rods will bake off volatile radio nucleotides such as cesium 137.
    These are biologically active, taken up in lieu of potassium and have a 30 year half life.
    The risk of a massive release of such materials as the pools boil dry is very high.
    In some respects, this is much worse than Chernobyl, because there are several reactors worth of material from all the years since the site started up at risk.

  2. Pingback: Fukushima Update: From Reliable Non-Hysterical Sources:

  3. Gregg Carse says:

    Also with due respect, I am a Ph.D in Nuclear Physics. This is probably the best written and most straightforward discussion of the Japanese nuclear event I have read to date. The likelihood of any form of meltdown is very small. The real problem (as discussed) was the poor siting of the backup diesel generators (also in two other articles).
    The hydrogen explosions have not greatly affected the primary containment vessels (8 inches of steel) only the outer (secondary) containment buildings.

    P.S. “etudiant” suggests you are studying or are a student. Wait for your degree.

    • suyts says:

      I just heard over the news, the U.S. is telling Japan that their utility companies are feeding them disinformation. This would explain much confusion. As it was originally told, I was incredulous as to why it would still be a problem days later. But later more information surfaced. I don’t think anyone is getting the straight story and I’m not in a position to judge the veracity of any.

      P.S. Steve simply reproduced someone else’ thoughts. I don’t know about anyone studying or being a student, and I’m not sure “etudiant” is in a position to know that either. It is my position that the day any of us quit studying, as the day we begin to die. I won’t wait for that day or a day someone confers a sheepskin upon me before I believe my opines are of value.

      • Gregg Carse says:

        Have done a lot of business in Japan and in the USA. The Japanese are not what you would call excitable. They remain calm and quiet under most circumstances. I tend to trust what they say. On the other hand, most of the press in the USA is looking to sell papers. I rarely trust any pronouncements from the US press or “officials”. The chairman of the NRC is a known anti-nuclear protagonist (Gregory Jazcko).

      • suyts says:

        I agree. I believe the word stoic is apt.

        And, yes, official news or MSM, they all tend to be anti-progress and given to alarmist misinformation. It drives me insane.

        Anyway, off to check the calculus of spheres on planes.

  4. nofreewind says:

    It seems to me the real problem is that there was not a backup power line strung from the grid. They counted on the backup on-site generators which were all wiped out. The plant held up under the earthquake, this will be fixed and more safeguards put in place, at a minimal long run cost. Just like the Gulf spill.

    • Paul H says:

      Presumably a few mobile generators on the backs of lorries would have been enough to keep the pumps working.

      If such a fleet had been held for emergencies in a safe area, they would have been in action in hours.

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