I was asked: "According to the international nuclear incident classification table, the Chernobyl nuclear power plant accident in the former Soviet Union on April 26, 1986, and the Fukushima Daiichi nuclear power plant accident in Japan on March 11, 2011, are the only two seventh-degree nuclear accidents in human history. So, is the harm of the nuclear accident in Fukushima, Japan, more serious than that of Chernobyl? ”
On this issue, I would like to briefly explain. Whether nuclear weapons or nuclear power plants, their energy comes from radiation energy, and the key lies in using artificial technology to control the radiation rate of atoms. Uranium is a radioactive atom whose isotope uranium 235 can produce a chain reaction, which can produce enormous amounts of energy. Uranium-235, with a neutron count of 143, is the only isotope in nature that can undergo controlled fission, can be used for nuclear fuel in nuclear reactors, and is one of the main raw materials for making nuclear weapons. The fukushima nuclear power plant's energy source is this uranium-235.
Fukushima nuclear accident in Japan
The chain reaction is a violent atomic fission, in which a nucleus of uranium-235 splits in half, releasing enormous amounts of energy and two or three neutrons. The neutron then continues to crash into another nucleus of uranium-235, which in turn continues to split. As a result, a large amount of energy was emitted, which can be described as a shot that could not be contained. It turns out that a small atomic nucleus also contains huge energy.
But chain reactions do not occur casually and require certain physical conditions. The volume of the neutron is small relative to the volume of the entire atom, assuming that the atom is the size of a football field, and the neutron is at the position of the nucleus, its volume is equivalent to a grain of rice. For neutrons, the inside of the atom appears empty. A neutron that wants to collide with a neutron from another nucleus, creating a chain reaction, requires a high concentration of uranium-235. However, the content of uranium 235 in nature is extremely low, and the ore in nature mainly contains uranium 238, but uranium 238 does not fission, so it needs to be refined to produce uranium 235, and it is a high concentration of uranium 235. Therefore, the refining of uranium-235 is a key step.
We need to note that for nuclear weapons, a chain reaction is required in order to obtain a huge nuclear explosion. And the nuclear power plant does not need such a violent explosion, so much energy has to be used slowly, can generate electricity. Therefore, nuclear power plants do not need such a violent chain reaction of atomic nuclei, mainly by technical means to control the output efficiency of radioactive energy. So, how to control the chain reaction without happening? It should be known that nuclear weapons explode because of the use of high concentrations of uranium-235, several large pieces are squeezed together by death, neutrons are easily chained with other uranium-235 nuclei, and nuclear power plants deliberately reduce the concentration of uranium-235 in nuclear fuel. As long as the concentration of uranium-235 is very low, there will be no chain reaction, and it will be safe. In general, engineers set the concentration of uranium-235 in nuclear power plants at 4 to 5%, which is safer and will not explode like nuclear weapons.
Engineers can pack small pieces of uranium-235 into a sleeve and turn it into something like a sugar gourd. This is the nuclear fuel rod of the nuclear power plant. A nuclear reactor would require hundreds of sugar gourds, erected like a forest of sugar gourds. Thus, assuming that some neutrons continue to escape from a sugar gourd, we can insert some carbon rods in the sugar gourd's forest that can absorb neutrons. When a neutron hits a carbon rod, it produces thermal energy. We let the water flow through them again, and we take the heat away. This heat energy is the energy emitted by the nuclear power plant.
Generally speaking, as long as there is no chain reaction, although the uranium of nuclear fuel is radioactive, its half-life is hundreds of millions of years, and the half-decay is so slow, indicating that its radioactivity is extremely weak. Sure, you're going to be unlucky to eat it, but occasional exposure won't be a big deal. The point is that the products of nuclear fission cause heat that melts these nuclear fuel rods. Therefore, even if the nuclear reactor stops working, it must continue to be cooled with cold water, otherwise the nuclear fuel rod will melt away. The accident at the Fukushima nuclear power plant in Japan means just that.
However, the pollution caused by the Fukushima nuclear power plant in Japan will not affect our country, and we do not have to worry too much.
When there was an accident that year, there were rumors on the Internet that the salt in the East China Sea was polluted, so many big mothers went crazy to grab salt, and one person bought a few tons, and could not eat it for a lifetime. But in fact, the Fukushima nuclear power plant accident in Japan has a little pollution of the adjacent ocean, but it does not affect the extent to which we eat salt. In order to cool the reactor, Japanese engineers demanded that seawater be poured into it. Under normal circumstances, the water in the inner layer and the cooling water in the outer layer are isolated. Now the reactor is broken, the cooling water is highly polluted, and at first they are still discharging into the sea, so the whole world is protesting. In this way, the Japanese did not dare to do so, and the polluted seawater was first sealed and stored in large jars. This polluted water is not yet allowed to be discharged directly into the ocean. So, for the time being, there is not much of a problem. Moreover, according to measurements, the radioactivity in the seawater near the Fukushima nuclear power plant has indeed increased, about 1,000 times. This value may seem frightening, but it is enough to threaten the ecology of the entire ocean. The size of the ocean is so large that a little bit of radiant water is nothing at all. Even in the waters off Fukushima, there are now a large marine biota, and marine scientists have monitored their survival and found that they have not been affected.
Moreover, in the entire Fukushima accident, no one has died directly as a result of the nuclear accident so far. News reports say that the nuclear accident did not cause any deaths, but the accident caused panic, the hospital urgently transferred seriously ill patients, some patients who had been waiting for the operation to continue their lives, did not do it, and died on the road. Others were scared to death, couldn't think straight, suffered from depression, and swallowed medicine as a result. In this way, more than 1,000 people died one after another. None of these people were killed directly by the nuclear launch, either poorly cared for or scared to death. In fact, if they hadn't left at that time, but chose to stay, they would have been fine. The greatest damage caused to human society by the Fukushima accident is not the dead, but the discrimination against the residents of Fukushima. The vegetables and fruits produced in Fukushima are not wanted outside, although there is no radiation at all after testing. Residents of Fukushima traveled abroad, and the hotel refused to provide them with services. The people of Fukushima became "second-class citizens".
Workers at the Chernobyl nuclear power plant
As for the Che Nobel nuclear power plant accident, the damage was much greater than in Fukushima, Japan. After all, there were direct casualties in that accident, and because it was inland, the area affected was larger.
Some online articles say that up to 200,000 people died in the accident, but that claim is unfounded. In practice, 43 people were identified as a result of exposure to nuclear radiation. The reason for the large number of "killed" people is that someone has made all the locals get cancer. They believe that if you are exposed to radiation, you will definitely get cancer, and if you get cancer, you will die, and there are about 400,000 residents in the local area, and they say that it is estimated that everyone will get cancer, and then half of the people will die, that is, 200,000 people. This is how the 200,000 people are calculated. But this is a mess, and being exposed to radiation will of course increase the cancer rate, but it will definitely not kill half of the people. There is no clinical medical data to prove their point. The real damage caused by the Che Nobel nuclear power plant accident was to leave the surrounding cities barren. But in the whole nuclear contaminated area, it is not that there are no people, so far, there are still eight or nine thousand workers in the nuclear pollution area, and they have not evacuated. Within a kilometer of proximity to the nuclear power plant, there is lush vegetation and a large number of wild animals living there. Explorers have seen many hares and wild mice.
In short, the Chernobyl nuclear accident was more harmful than the Fukushima nuclear accident in Japan.
Academician He Zuoxiu
Academician He Zuoxiu, a nuclear physicist, has his own views on the safety of nuclear power plants. In November 2012, Academician He Zuoxiu issued a statement: "I oppose the construction of nuclear power plants inland, but I am not an anti-nuclear person." Why am I against building inland? Because once there is a big accident in the inland, it is terrible! I advocate that nuclear power plants be built to the seashore, and once there is a major accident, they can also be discharged into the sea, and the Damage to the Chinese people can be smaller. I am more advocating the use of nuclear technology on ships, nuclear submarines, nuclear aircraft carriers, and even destroyers and ocean-going merchant ships are all changed to nuclear power. ”
Author: Skeptical Explorer