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Review
Deep underground in Chernobyl, the memory of a nuclear catastrophe that time cannot erase is hidden. This underground bizarre, a melted furnace core shaped like a giant elephant's foot, has once again attracted the attention of scientists after many years.
It is not only a remnant of the Chernobyl nuclear accident, but also a mysterious interpretation, why the imprint of the nuclear disaster has not faded as the years go by? Digging deeper into this mysterious phenomenon may reveal deeper secrets in the field of nuclear energy safety.
Chernobyl disaster
On April 26, 1986, the Chernobyl nuclear power plant suffered the worst nuclear accident in human history. The plant's No. 4 reactor went out of control during a safety test to test whether the reactor could rely on turbine inertia to keep the emergency cooling system running in the event of a power outage.
However, due to the wrong operation of the inspectors and the design problems themselves, serious accidents occurred during the test. The reactor's power soared to more than 100 times its normal operation, causing the internal fuel rods to begin to melt, producing large amounts of hydrogen and steam. Then, two violent explosions occurred, blasting open the roof and roof of the reactor, creating huge holes.
As many as 520 radioactive materials enter the air along with the shock, some of which have half-lives of hundreds of years. The spread of these materials to the western part of the Soviet Union, Eastern Europe, Northern Europe, and even some parts of North America with wind direction and rainfall caused widespread nuclear contamination and ecological damage.
The accident caused more than 400 times more radiation damage than when Japan was bombed, which is equivalent to exposing everyone in the world to a radioactive nuclear bomb.
The impact of this nuclear disaster was far-reaching, not only having a huge impact on the Soviet Union at that time, but also bringing great difficulties to the safety of nuclear energy and environmental protection around the world.
It is estimated that the disaster caused about $200 billion in economic damage, making it the most costly catastrophic event in recent history.
After the Chernobyl nuclear accident, the Soviet government quickly organized large-scale operations to extinguish fires, stabilize reactors and clean up the surrounding area. The disaster mobilized 600,000 people, but many developed cancer and other diseases from excessive radiation.
Nearby towns, such as the city of Pripyat, were urgently evacuated and cordoned off, turning into an abandoned ghost town. The Soviet government covered up and misrepresented the truth of the accident until a few days later, triggering global shock and accusations. The accident also indirectly contributed to their political reform, disintegration, and international cooperation on nuclear safety.
Even decades later, the Chernobyl nuclear power plant site remains a dangerous place that requires constant monitoring and maintenance. This is a profound lesson for all of humanity and reminds us that we must be cautious and take nuclear energy seriously.
Rekindled core
The Chernobyl nuclear accident was one of the worst nuclear disasters in human history, resulting in thousands of deaths, millions of radiation exposure, and enormous environmental damage.
After the accident, the core of the No. 4 reactor of the nuclear power plant melted due to the explosion and high temperatures, forming a highly radioactive substance known as Corium.
This substance, which resembles lava, flows and penetrates the structure of the reactor, solidifying into blocks of different shapes in the ground. One of the most famous of these is known as the "Elephant's Foot", which is shaped like an elephant's foot.
The "elephant's foot" was only seen six months later, and it was later taken by a team that went to the site of the incident to investigate it and took pictures of it with remote-controlled video equipment.
The radiation intensity of this melted furnace core was extremely high, reaching 12,000 roentgeniums per hour, which was enough to kill in a matter of minutes. Rescuers can only hit it with a gun, retrieve some fragments for analysis and study.
The fragments showed that the internal temperature of the melted furnace core was still unusually high, reaching 300 degrees Celsius, indicating that the nuclear fission reaction was still underway, albeit at a slower rate. This is where the core is still generating heat.
There can be two main reasons for core re-ignition.
- The first is changes in the environment and materials, which can lead to the leakage and exposure of more radioactive materials.
- The second is the thermodynamic properties of nuclear reactions, which may maintain self-heating and chain reactions.
The first reason has to do with the cooling of the furnace core. After the accident, in order to prevent the furnace core from penetrating the foundation and polluting the groundwater, rescuers built a cooling layer under the furnace core, using water and boric acid to absorb heat and neutrons.
However, the cooling layer is not perfect, and there may be water infiltration or evaporation. Water has a twofold effect on nuclear reactions: it accelerates nuclear reactions, but it also absorbs neutrons and inhibits nuclear reactions. This balance causes the core to re-ignite, which is affected by water flow and changes.
The second reason is related to the nature of nuclear reactions. The nuclear reaction releases a large amount of heat energy, which increases the temperature of the furnace core, resulting in thermal expansion and volume increase.
Thermal expansion reduces the core density, making it easier for neutrons to escape, reducing the rate of nuclear reactions, and forming a self-regulating mechanism. The higher the core temperature, the lower the reaction rate, and vice versa, which remains relatively stable.
There are two major hazards associated with core reignition. The first is radiation pollution, which releases large amounts of radioactive materials and has an impact on the environment and biological health. Second, it may cause a secondary explosion.
Although not as violent as the initial explosion, it is still threatening. Evaporation or contact with other combustible materials can increase pressure and cause an explosion, causing greater physical damage and the release of radioactive material.
epilogue
For humans, the resurgence of the "elephant's foot" meltdown is a stark reminder that we must always be vigilant and constantly improve our safety measures while using nuclear energy.
This historic event has awakened deep concerns about the environment, human health and nuclear safety, and has inspired the international community to work more closely together in the field of nuclear safety.
Years later, the resurgence of the "elephant's foot" meltdown core remains a scientific mystery, but it has also prompted a deeper exploration of the importance of nuclear safety.
For the future, we need to continue to accumulate lessons and continue to pay attention to and strengthen the prevention, response and monitoring of nuclear energy accidents to ensure the safety of people and the environment, and maintain our common home.
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