Chernobyl disaster - 20 years look back

At 1:23 minutes on April 26, 1986 at the Chernobyl Nuclear Power Plant, in the Republic of Ukraine of the former Soviet Union, there was a unique accident in the history of the world atomic energy industry.

Dr. El Baradei, Director of the International Atomic Energy Agency (IAEA), called it a "disaster but an important turning point for the IAEA." It shakes the world's belief in the safety of atomic energy, the huge source of clean energy that humanity hopes that humanity will never have to worry about the energy shortage again. .

The area affected by the chernobyl disaster, the horizontal lines are high radioactive contamination.( Photo: Ki4u.com )

Before 1986 few ordinary people thought that nuclear power incidents could occur. People believe in science, believe in the literal sense and the perfect sense of responsibility of these super science experts. But today Chernobyl became a word of mouth. Newspapers write about it much and contradictively, creating a heavy psychological pressure on the people who lived near the accident, on residents of other countries with nuclear power plants, and on planners. energy policy of nations. The situation was so serious that in 2004, 18 years after the accident, the United Nations had to organize an international workshop with the participation of the IAEA and all relevant agencies of this organization, together with other countries. Russia, Ukraine, Belarus to screen all the news, distinguish right from wrong, give a summation to the General Assembly. This international forum has "provided honestly responsible information about the post-Chernobyl reality situation", that is to make it possible to distinguish fabricated news that much in the boom of information today. like mushrooms after rain. But actually, even among professionals, the assessment of the extent of the impact and the extent of the disaster are also very different.

How did the accident take place?

It is difficult to write and even more difficult to read, although it is very difficult to write and describe the events and causes of Chernobyl accident. It involves many concepts and terms that many people do not know. This is how it is. The Chernobyl nuclear power plant is equipped with the first designed reactor in the Soviet Union, on the basis of developing plutonium-producing furnaces used for former military purposes. The design of this type of furnace is potentially dangerous. There is an easy way to compare. The marbles at the bottom of a deep pit are called in a stable equilibrium, because if there is an impact that causes movement, it will roll back to its original position. Nuclear reactors in western countries are designed so that adjustments to safety status can take place on their own, just like a self-rolling marbles on a deep pit, if any impact makes it was teleported out of that state. That design principle creates the intrinsic safety factor of the reactor. Since the beginning of the 1970s, many experts have pointed out that the Chernobyl reactor type does not have that important factor. But the Soviet Union's Nuclear Safety Rules do not guarantee that the built reactors must have intrinsic safety factors, must be stable in different capacity areas, must respect the principle. " deep defense "to prevent accidents.

The worst thing was that in Chernobyl there was no protective kiln system (containment), the deciding factor of the "deep defense" strategy, so that when the reactor broke, radioactive material was confined to it. Do not escape.

But design mistakes only play a potential risk. It is the habit of disregarding human laws to turn those risks into reality. After the Chernobyl disaster, the term "safety culture" was born and the construction of that culture was considered by IAEA to be an especially important work of nations that have or will have nuclear power. .

At that time, people wanted to do an experiment when the furnace ran at a very low capacity (compared to the rated capacity). Because the furnace operates unstable at low power areas, the automatic furnace shutdown system will work to avoid malfunction. In order to be able to conduct experiments, people have made a deadly decision, regardless of safety culture, to lock the automatic furnace signal system. Therefore, when the furnace capacity increases rapidly, due to instability in low capacity areas, it is impossible to bring the furnace to a safe state. The power increased rapidly to the level of water as the thermal load was not enough to cool but evaporated violently. A large explosion broke the dome weighing about 1,000 tons of the reactor and part of the kiln. At high temperatures steam decomposes or is deoxidized to form hydrogen gas. Because there is no reactor protecting the reactor, the extremely important protective barrier of the nuclear reactor, the air from the outside spills into a hydrogen explosion and burns thousands of tons of graphite retardants throughout 10 terrible day and night, temperatures up to 2000 ^o C. Not a nuclear explosion, merely a vapor explosion, a chemical explosion, but without a protective furnace, the amount of radiation is about 100 to 400 times that of the atomic bomb that Americans dropped on Hirosima, chemical explosions and graphite burns thousands of meters high. This cloud of death dust was carried away by the wind, to the north as far as 500km, leaving consequences until now.

How many people died in the Chernobyl disaster?

Only 31 people died, according to data from the International Atomic Energy Agency (IAEA). The death toll is not much different from a car crash, but the terrible consequences of disaster are elsewhere. The Chernobyl nuclear power plant, although bearing the name of this small town of 12 500 people, is still 15km away from it. Close to the Factory, only 3km, is Pripyat town where the Pripyat river flows smoothly to pour into Kiev reservoir. All 49,360 inhabitants of the beautiful and unfortunate town must leave their homes, their properties, within 36 hours of the accident. Within a few months, an additional 67,000 people had to relocate to a new government arrangement, bringing the number of residents to 116,360. If even people who leave their neighborhoods by fear of radioactive effects, it is estimated that the total number of divorcees can reach about 200,000.

Not over yet. By 2004, at least 1,800 cases of children aged 0 to 14 years were reported when accidents occurred, with thyroid cancer. A significantly higher rate than normal, because the thyroid gland of children is susceptible to radioactive iodine, a cancer stimulant. Luckily, there has been no increase in other types of cancer, even in the team of people who work to solve the consequences of accidents.

How wide is the radiation area?

There are reports that only about 18,000 km2 of cultivated land are allowed to be cultivated and about 35,000 km2 of forest are affected by radioactive material. But many environmental experts and organizations claim that there must be 150,000 square kilometers in Belarus, Russia and Ukraine, which is nearly half of our country, contaminated. The land lies within a distance of 30km from the Factory, calculated about 3 times the area of ​​Hanoi Capital, is considered a restricted area. Many mutations to plants and animals have occurred after the accident. Some plants change their appearance and many animals are born deformed.

How do people deal with the consequences of accidents?

There are no exact numbers on the force involved in solving the accident consequences. Russia offers a list of nearly 400,000 people involved in this hard work, along with nearly 600,000 people involved in those activities. They dismantled dilapidated areas, built waste storage, dams, water filtration systems, cleaned factories and surrounding areas . By 'long arm method' people built graves. giant, burying the whole number 4 reactor to prevent radioactive material from continuing to spread out. But today this huge concrete block has cracked, requiring treatment to avoid radioactive leaks and other events. Radioactive grave rushes when another accident is very far from the standards of burnt burnt fuel. The following fuel rods used, if not included in recycling, must be buried in waste warehouses located in the depth of hundreds of meters underground, in places with suitable stratigraphic structure, geological conditions and hydrology. , along with many sustainable protective barriers of ten thousand years.

The use of contaminated soil for cultivation requires a lot of international support. Scientists from advanced countries focus on the direction of planting plants that are more likely to concentrate radioactive material on the stem, branches, leaves, and shells, but the seeds do not contain radioactive material, so they are still valuable. sacrifice. For example, the World Food Organization (FAO) has provided the technique of separating cesi from milk and meat. FAO also helps Belarus choose the option of growing canola on contaminated soil. The radioactive material focuses on the stem and seed skin of this plant, not found in seeds, so canola oil can still be used as food.

But there is nothing that can cure the pain of the scent of tens of thousands of people who are forced to leave their familiar villages. No one has reassured millions of people, who have lived in the accident area or have taken part in the recovery, always thinking about some unfortunate day that illness will develop on their bodies or their descendants. Some people commit suicide because of despair. Many couples do not dare to give birth because they are afraid of a malformed child. And the human faith in nuclear energy is probably a long way from being recovered.

How is Chernobyl now?

The view of nuclear power plants after the disaster, 1986. ( chemcases )

During the disaster, in the No.4 reactor there were 200 tons of uranium fuel. People vary greatly in the amount of uranium released when a disaster strikes. The Ukrainian authorities asserted that their 15-year studies showed that 95% of uranium fuel remained in the reactor after the explosion. Many others estimate the amount of fuel released is between 3-20%. But in 2002, two well-known physicists, Konstantin Checherov of Moscow's Kurchatov Institute and Sebastian Pflugbeil, director of the Berlin Radiation Protection Agency, announced on the German National Television (ZDF) that most of the time. whether it has escaped the reactor, the remaining part is negligible.

No matter how evaluated, more than 100 radioactive elements were released into the atmosphere in quantities of about 1 percent to 1 per thousand of the fallout that the nuclear weapons tests in the 60s and 70s created. out. Most of these elements are short lived and quickly disappear. But stronti 90, cesium 137 has a 29-year and 30-year half-life, which means that after 29, 30 years their radiation has only been halved, still dangerous now and many decades later. . But today, despite high levels of radioactivity, many rare animals have returned to restricted areas in large numbers such as beavers, elk, wild boars, wolves, carnivorous animals and lots of birds. . The dams set up by the beaver families make the water level rise, widening the lagoon, enriching aquatic life. Forest encroached on pastures and old villages. Some residents, especially the elderly, could not bear the pain of divorce, missed their memories, returned to the forbidden zone on their own. But there is no school for children in this area to avoid the effects of radioactive substances on young people. Visitors were also allowed to visit the accident site.

Last words

In order to meet the rapidly increasing electricity demand during the industrialization process, in our country's conditions, nuclear power will probably be chosen as an inevitable. However, this technology is quite economical and low emission of greenhouse gases also makes many people afraid. There is room for lack of information and knowledge, but many places are reasonable. Nuclear experts claim that the technology has improved a lot over the past few decades, that the design of today's reactors ensures intrinsic safety, so that never will be. I can get a Chernobyl again. Many people believe and surely everyone expects that to be valid.

Some other scientists "wisely" advise policy makers that a "wait and see" strategy should be used, but its basic content has not yet made any specific conclusions about selection. Selecting future energy sources, pushing as far as possible the day to think about nuclear power, awaits the introduction of new reactor generations with new technological advances. The argument is also convincing.

But the main cause of the 1986 disaster did not seem to be the weak level of nuclear technology at the time but in law and people. It is thought that a strong rule of law needs three elements: The law must be affirmed in theory and proved by the fact that it is paramount; The law must be perfectly built, ie to be complete, accurate, feasible, non-contradictory and explicit; And people have a habit of obeying the law. Chernobyl happens because loose safety rules allow for unsafe designs to be allowed to be built, while operators are disregarding rules, which is the lack of at least two of the three. It should be added that, in 1983, that was only three years before the Chernobyl disaster, a similar incident, at a reactor of the same type as the Chernobyl reactor, happened in Lituania, but fortunately. not very big. Unfortunately, those responsible have not paid attention to this warning. Therefore, building a strong rule-of-law state is to create a protective layer that decides to prevent incidents like chernobyl, not just for the nuclear industry.

Do Quy Son ( Vietnam Atomic Energy Institute )