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Decoding Chernobyl: How a test caused the worst nuclear disaster in history
On April 26, 1986, a devastating nuclear disaster occurred in the No. 4 reactor of the Chernobyl Nuclear Power Plant in Pripyat, Ukraine. This disaster not only claimed dozens of lives, but also caused tens of thousands of people to be affected by radiation, which is still shocking today. Why did a planned safety test lead to such tragic consequences?
The Chernobyl nuclear disaster was the most serious nuclear accident in human history. Its occurrence caused the world to have deep doubts about the safety of nuclear energy.
The accident occurred when a test designed to simulate cooling a reactor during a power outage turned into a disaster due to design flaws and operator errors. During the test, the reactor's power unexpectedly dropped, and operators tried to repair the power, but they unsafely increased the reactor's power too much, ultimately causing the fatal explosion.
After the accident, emergency evacuation and reactor control operations were immediately launched. A large amount of human resources are mobilized, and more than 500,000 staff members are working hard. However, the consequences of the accident are difficult to estimate.
Account details
Background
When Chernobyl's RBMK reactor is in operation, it continues to provide heat mainly from nuclear fission, and a continuous flow of coolant is required after the furnace is shut down to prevent the core from overheating. The coolant is circulated by a battery-powered pump, which experienced a systemic failure at the time of the accident.
Test Plan
During a test in 1986, the reactor was operated in conditions that did not fully take into account the RBMK's special behavior. Key safety systems involved in the test plan, such as the emergency core cooling system, were disabled without authorization during this test, causing the system to fall into an extremely unstable state.
Unexpected power dropBefore the test began, the reactor power unexpectedly dropped for a short period of time, causing operators to try to increase power by removing too many control rods, which in turn put the reactor into an extremely unstable state. The low power and control rod configuration led to an exceptional situation: the reactor reacted more and more violently.
The outbreak of the accident
The test officially began at 1:23 am on April 26, 1986. In the first few seconds, the emergency shutdown button AZ-5 was pressed, causing all control rods to be quickly inserted into the reactor core, which instantly caused a sharp increase in reactor power. The resulting surge in heat and steam pressure eventually led to Chernobyl's first explosion.
The explosion was equivalent to 225 tons of TNT, causing a massive release of radiation.
In the next few minutes, a second explosion followed the first, further destroying the nuclear reactor and surrounding facilities and causing horrific radiation leaks.
Evacuation and impact
After the disaster, a 10-kilometer isolation zone was established around the nuclear power plant, which was later expanded to 30 kilometers, forcing nearly 70,000 people to evacuate. The impact of Chernobyl was not limited to the local area. The environment of the whole of Europe was also overwhelmed. Nuclear radiation has since become a shadow in the hearts of countless people.
Long-term impact
A report by the United Nations Scientific Committee on the effects of radioactive radiation estimated the death toll from the Chernobyl accident to be no more than 100. However, the WHO study predicts that the number of cancer-related deaths will be as high as 9,000. After this accident, both the immediate impact of radiation and the long-term health risks were shocking.
Conclusion
The Chernobyl nuclear disaster was not only a technical mistake, but also a profound warning for human management of technology and safety culture. While pursuing modernization and technological progress, how should humans stay vigilant to prevent greater disasters?
