Explosion at the Chernobyl Power Plant: What Happened and Why It is Still Unsafe

Author: Silvia DiPaola

Editors: Galiba Anjum and Liane Xu

Artist: Nicole Tseng

When the word “Chernobyl” is heard, one might think of a nuclear power plant in flames as dangerous radiation envelops the area, or perhaps a large-scale explosion accompanied by a movie-styled mushroom cloud. No matter what scenario comes to mind, the cold hard truth about the site of the Chernobyl Accident of April 1986 in Ukraine will remain the same. The site is still unsafe and will continue to remain unsafe for another 20,000 years.

The Chernobyl Nuclear Power Plant in Ukraine exploded on April 26, 1986, causing a fallout of 100,000 km² of land surrounding that area. The causes of the explosion are debated to this day, but the general consensus is that the first explosion was caused by an excess of steam inside a reactor. Water was used in the reactor as a coolant to prevent the core from overheating by removing excess heat and steam from the reactor. However, the poorly designed RBMK-1000 reactors used graphite, which exacerbated the heating process by producing more steam instead of mitigating it, causing the core to overheat. The excess steam building up in the cooling pipes caused a power surge that the operators could not shut down. After the explosion occurred, Reactor 4 was destroyed and a vigorous fire was produced, which ended up spreading to the surrounding buildings. Radioactive debris from the fuel and the components of the reactor rained down over the area and were carried to neighboring countries by the wind.

Most of the radiation produced by the reactor explosion was from the fission products Iodine-131, Cesium-134, and Cesium-137. Isotope Iodine-131 in particular builds up in the thyroid gland and can spread rapidly through the air. Oddly enough, that same isotope is used in thyroid cancer treatment, but it can also cause cancer in the thyroid. However, it has a relatively short half-life, how much time it takes for half of an isotope’s atoms to disintegrate, of 8 days. The cesium isotopes, however, have a longer half-life of 30 years, which makes them more dangerous compared to Iodine when emitted into the environment. There were around 30,000 people near Chernobyl on that day, and they were exposed to around 45 rem of radiation. While this did not cause them to have radiation sickness, it did increase their risks of acquiring cancer by 1.8%.

Heroic workers had stayed behind at Chernobyl after the explosion to try and contain the radiation leaks as much as they could. As a result, the building of a sarcophagus around reactor 4 commenced. It was completed in 2017 and ended up being a staggering 843 feet wide, 531 feet long, and 356 feet tall. It was designed to completely envelop reactor 4 for at least another 100 years while it will remain radioactive. However, the area, commonly referred to as the Exclusion Zone, still harbors radiation that will remain radioactive for another 3000 years. The reactor itself will remain for at least 20,000 years due to the long half-lives of some of the isotopes emitted in the explosion.

Now for the overarching question—why does the site of Chernobyl have restricted access after all this time, but areas like Hiroshima are safe? It is partly due to the differences in each atomic explosion. The Chernobyl reactor used a lot more nuclear fuel than the bomb dropped on Hiroshima, and the explosion occurred at ground level as opposed to in the air in Hiroshima. Chernobyl had 180 tons of nuclear fuel and seven tons of that escaped into the atmosphere, as compared to the two pounds that reacted in the Hiroshima explosion. Some of the isotopes released in the air at Chernobyl, as aforementioned, have a long half-life and will remain radioactive for many years. Thus, although Chernobyl resulted in 31 deaths and the explosion at Hiroshima resulted in over 70,000, the area around Chernobyl is more dangerous.

The Exclusion Zone is illegal to inhabit, but it does not stop people from doing so. Around 130-150 people still live in that area. However, the radiation levels in this area’s atmosphere do not pose a risk to these people. In reality, it is the soil contamination that could pose a threat to their health. Grass can be contaminated with the radioactive isotopes and then be eaten by cows, causing the milk to be contaminated as well. If the people living there ingest it, it could result in major problems for them. In large enough quantities, these isotopes can damage human cells and lead to thyroid cancer.

Although it may be unsafe for someone to live there, people still have the option of visiting. It is open to visitors, but it is important to abide by the rules of the area to limit radiation exposure as much as possible. It is dangerous to go in the woods near Chernobyl, as there is more radiation emanating from the soil and trees. It is best to stick to the trails and be on the lookout for signs guarding areas with high radiation levels. It’s also important for people to bring their own Geiger counter so they can measure the amount of ionizing radiation where they are, thus if levels are too high they know to leave. It generally is not recommended to visit the area where a nuclear reactor exploded and emitted tons of radioactive isotopes and radiation into the atmosphere, but if someone is feeling a bit rebellious, they are more than welcome to visit!


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