Meltdown at Chernobyl Nuclear Power Plant

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The Chernobyl Meltdown happened on this day in 1986. i-e2a7f324b13ae36293e04a2119b58d06-chernobyl_hydroceph.jpg

On 26 April 1986 at 01:23:40 a.m. (UTC+3) reactor number four at the Chernobyl Nuclear Power Plant located in the Soviet Union near Pripyat in Ukraine exploded. Further explosions and the resulting fire sent a plume of highly radioactive fallout into the atmosphere and over an extensive geographical area. Nearly thirty to forty times more fallout was released than Hiroshima. The plume drifted over parts of the western Soviet Union, Eastern Europe, Western Europe, Northern Europe, and eastern North America. Large areas in Ukraine, Belarus, and Russia were badly contaminated, resulting in the evacuation and resettlement of over 336,000 people. According to official post-Soviet data, about 60% of the radioactive fallout landed in Belarus. *

From the UN’s Chernobyl site:

Recent research has shown that people in the Chernobyl region still lack the information they need to lead healthy, productive lives. Information itself is not in short supply; what is missing are creative ways of disseminating information in a way that induces people to change their behavior. Moreover, propagation of healthy lifestyles is at least as important as providing information on living safely with low-dose radiation. To improve the population’s mental health and ease fears, community activists will be mobilized to deliver truthful and reassuring messages to dispel the misconceptions surrounding Chernobyl. *

Chernobyl Legacy (Film) SitePhotos by Robert KnothThe Chernobyl Forum Publication (PDF)

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17 thoughts on “Meltdown at Chernobyl Nuclear Power Plant

  1. A friend of mine was living in Romania at the time. She and her boyfriend were camping and so they did not know about this event. When they reached a mountain lake they didn’t know why all the fish were dead. (floating on top of the water) Once the returned home a few days later they figured it out.

  2. Might I point out that there was no meltdown at Chernobyl? It was a non-nuclear explosion that scattered nuclear material which is much much worse than a meltdown. Just ask Three Mile Island, which was an actual (partial) meltdown.Meltdown is when the core is no longer getting cooled, and it melts. It is so energetic that it “melts down” through the shielding and seeps into the groundwater.

  3. From Wikipedia, the Nuclear Meltdown entry, FWIW:”Several nuclear meltdowns of differing severity have occurred, from localized core damage to complete failure of the containment. In some cases this has required extensive repairs or decommissioning of a nuclear reactor. In the most extreme cases, such as the Chernobyl disaster, deaths have resulted and the near-permanent civilian evacuation of a large area was required.”

  4. Meltdown/explosion.The Three Mile Island event receive much ongoing news coverage. One of the concerns was that a buildup of hydrogen gas might explode. A Washington, DC, television news reporter referred to the “danger of a hydrogen bomb explosion…”

  5. I think there are three things going on here.A nuclear reactor consists of a nuclear pile that produces heat and other products (like gas). It is very hot. The isotopic decay reaction is what produces the heat (a desired effect … this is the energy to be converted to electricity) but it is also dangerous because a pile can get “too hot to handle” … keeping the pile in the correct temperature range is key.So there are three things that can go wrong with a nuclear pile. One is that the heat gets out of control, and the physical structure designed to hold the material breaks or melts way. This could cause the nuclear material to assemble in a smaller space than ideal, causing even more total heat and more focused heat. The “china syndrome” is the idea that this heat would be so extensive that the very hot mass of nuclear material would melt its way through the base of the reactor container, the building, the foundation, into the bedrock, eventually reaching china. Of course, the part about china is added for poetic purposes. The point is that the details of what would happen if a full nuclear pile was assembled into an uncontrolled mass with no control rods are beyond contemplation by engineers.It is actually the engineers themselves that would probably be heading for China. Or wherever.The second thing that can happen is an actual nuclear explosion, where the chain reaction gets to the point where heat isn’t the only problem, but a full blown almost instantaneous chained series of nuclear events occur and you get an A-bomb (or, I suppose an H-bomb). The chances of this happening are astronomically small for two reasons. First, if you actually want to build a nuclear bomb, there are many things that must happen to make it work, most of which are not present in a nuclear reactor. Second, there are design features that are actually not that difficult to implement that minimize this.The third, and very very likely possibility is a “regular” (non-nuclear) explosion that breaks open the containment and spews nuclear stuff everywhere. In theory, gas can build up and cause such an explosion without there being a meltdown, but if there is a meltdown, the ways in which a gas-based explosion can occur are probably multiplied.That appears to be what happened at Chernobyl. A meltdown, in progress, changed over to a gas explosion. At 3 mile island, the situation of an ongoing beginning meltdown did not turn into an explosion, but yes, that would perhaps have been a “hydrogen explosion” which is NOT an H-bomb! Just hydrogen. Exploding.

  6. While the Chernobyl accident had and continues to have serious consequences for the lives of people living in the region, these images do not accurately reflect what is currently known about the long-term health consequences. All of the injuries and diseases shown in this video, as severe and debilitating as they are, do come about without exposure to ionizing radiation.

    From the UN’s Chernobyl health assessment from 2000 (page 516),

    “Apart from the substantial increase in thyroid cancer after childhood exposure observed in Belarus, in the Russian Federation and in Ukraine, there is no evidence of a major public health impact related to ionizing radiation 14 years after the Chernobyl accident.”

    Also, from the Nuclear Energy Agency’s 2002 Update to Chernobyl: Ten Years On,

    “There have been many reports of an increase in the incidence of some diseases as a result of the Chernobyl accident. In fact, the accident has, according to present knowledge, given rise to an increase in the incidence of thyroid cancers. Also, it has had negative social and psychological consequences. As far as other diseases are concerned, as yet the scientific community has not been able to relate those to the effects of ionising radiation. However, large research projects have been conducted and are under way to further study the matter…”

    More information is available from the UN Scientific Committee on the Effects of Atomic Radiation and from the World Health Organization.

  7. The argument has been made that the “health science” industry is not capable of making these kinds of assessments because the techniques are not developed and because of the political bias against them. Note that many of your sources are the nuclear industry itself.

  8. >The argument has been made that the “health science” industry is not capable of>making these kinds of assessments because the techniques are not developed and>because of the political bias against them.Even if this were true, the fact remains there is not yet a demonstrable link between Chernobyl and diseases in the regional population other than thyroid cancers.> Note that many of your sources are the nuclear industry itself.I quote only one industry source, NEA. Besides, I figured since the Robert Knoth collection included Greenpeace as a reference, then the Nuclear Energy Agency would be fair game. The NEA’s results are consistent with the other references, which are international organizations.

  9. I should note that the photo essay linked to here is about Soviet/Russian nuclear projects in general and is not confined to Chernobyl.By the way, something like 200 thousand fetuses were aborted in the weeks/months after Chernobyl by mothers who feared negative consequences.

  10. > By the way, something like 200 thousand fetuses were> aborted in the weeks/months after Chernobyl by mothers> who feared negative consequences.Yes, I’ve heard that too; it’s interesting.I’m a PhD candidate in a nuclear engineering department, and other students and faculty occasionally mention that casually in the hallway, though I have never been able to confirm it independently. I would be interested if anyone knew of a reference.

  11. Ketchum, L.E. 1987. ?Lessons of Chernobyl: SNM members try to decontaminate the world threatened by fallout. Experts face challenge of educating public about risk and radiation.?

  12. Aye – no doubt some fuel at Chernobyl melted, the reactor had a positive void coefficient which meant that a positive feedback loop got started and it ran away with itself.But if the fuel at Chernobyl did meltdown at all, nobody was particularly bothered by it at the time. The people on site and at Pripyat etc, were mostly concerned about the significant amount of radioactive material in the atmosphere, rather than whatever amount had managed to melt through the shielding into the ground. (well the people on site were mostly (fatally) concerned about the chemical fire…)I mention it because when deciding on nuclear energy policy, and an expert says that the worst case scenario is a meltdown – it is detrimental to the decision making process (and the public understanding of science) if people automatically associate ‘meltdown’ with ‘Chernobyl’ rather than ‘Three Mile Island’.There are risks with modern reactors, but we should try and ‘frame’ them in a more accurate fashion so that we can make informed choice about our future relationship with energy production. :-p

  13. One thing I see no one has mentioned is the fact that Chernobyl had no containment building, something that is required on all US nuclear plants. All containment buildings are to be at least 3-4 feet thick of concrete and most contain steel rebar cables, and what was the major reason that Three Mile Island didn’t release any radiation outright.The Soviets apparently thought that their plants were perfect and didn’t need a containment shelter. Then they had to concoct one above a very dangerous steam-explosion fire that was emitting lethal amounts of radiation, and now have to construct a much-better containment to replace the sarcophagus that is starting to fall apart.

  14. In all the discussion of the technical aspects of what happened at Chernobyl No. 4, I think one critical bit of information is missing here.The Chernobyl reactor was [u]graphite-moderated[/u], a design that I’m certain the NRC would never permit for power generation in the U.S., due to the inherent hazards of that design. It is difficult to persuade graphite, a crystalline form of carbon, to burn, but once you get it started it is an exceedingly difficult fire to put out. The graphite fire at Chernobyl was the reason it took so long to get the whole mess under control.U.S. power reactors are moderated with water, of one type or another (heavy or regular), at various temperatures and pressures, depending on the design. One of the primary safety features of American reactors (and others outside the former Soviet Union) is this water moderator: If reactor-core temperature goes wildly out of control, the moderator will at some point boil away, stopping the reaction (well, pretty much, depending on severity of the accident and what configuration the core melts down into).The moderator is necessary to slow down neutrons so that they can be absorbed by the fuel (uranium, plutonium, thorium, or a mixture of these) and keep the chain reaction going. Without a moderator, the reaction simply will not start or proceed. Moreover, water is nonflammable, and so will not cause a fire that, in the absence of containment, would create an updraft that would carry radioactive death far and wide through the atmosphere — as is the case with graphite.A common misconception is that a nuclear reactor used to generate power could become a “nuclear bomb” in case of an accident. That is, a reactor gone wild could create a Hiroshima- or Nagasaki-type mushroom-cloud explosion. Not so. If that were true, it wouldn’t be such a difficult proposition for nations to develop nuclear weapons. The technicalities required to build a working nuclear weapon are so picky that it is a very difficult thing to achieve.By the way, I think the Soviets chose their design, and not to provide containment, simply because they were strapped for funds. They built Chernobyl “on the cheap,” crossed their fingers, and hoped for the best, in my opinion.

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