Why Is Chernobyl Still Radioactive and Hiroshima Is Not?

If you think of the two most deadly nuclear accidents, you will definitely remember the bomb thrown at Japanese cities and the Chernobyl explosion. Both of these disasters have caused thousands of deaths. However, Hiroshima is populated now, while the Chernobyl exclusion zone is still dangerous for people to live in.

In the article, we will answer this question. You will learn about the difference between these two accidents and understand why one spot is safe and the other one is not.

Why Is Chernobyl Still Radioactive and Hiroshima Is Not?

To begin with, let’s look at both accidents and understand their reasons.

Chernobyl and Hiroshima: Accident in Japan

At the end of World War 2, the USA decided to bomb Japan with nuclear missiles. Their plans were realized on August 6 and 9, 1945. The aims were Hiroshima and Nagasaki cities. The bombs were named Little Boy and Fat Man for each city respectively.

The bomb that we are interested in is called Little Boy. It was a uranium-fueled bomb approximately 10 feet long and two feet across. Its weight was about 10,000 pounds. The nuclear power of the bomb was 140 pounds of uranium.


It exploded in the air, just 2000 feet above the ground. It is estimated that more than 70,000 people were killed on the day of the explosion, and almost 100,000 were injured. The whole city was destroyed. As the WHO believes, more than 2,000 people have died from cancers as a result of the catastrophe since 1945 till the present time.

Chernobyl and Hiroshima: Accident in Ukraine

1986 has seen another nuclear accident, that time in Ukraine. The reasons were completely different. Yes, it was also induced by humans, but the Ukrainian explosion could have been avoided if the decision-makers in the Soviet Union would have thought about people rather than performance.

Reactor Flaws

There was a built-in instability in the reactors on the nuclear power plant. It caused the vicious cycle on the night of the explosion: the coolant was decreasing, but the reaction went up, so with the coolant going down, the control over the reactor was lost.

Besides, the safest material for the construction of nuclear power plants is a steer liner plate, post-tensioning, and steel-reinforced concrete. The Soviet Union used only heavy concrete, which wasn’t able to contain the uranium.

Human Element

There was a system test on the power plant on the night of the explosion. The electricity inflow was low because of the breakage of the line, so it was advisable to reschedule the test. It wasn’t done. Many of the safety systems were disabled due to the test, leaving only 6 out of 205 control rods on.

When the situation went completely wrong, employers tried to stop the reactor, using the AZ-5 button. However, they didn’t know about the built-in instability, so pressing this stop button only raised the reaction. We know the result of this action.

Why Is Chernobyl Still Radioactive and Hiroshima Is Not?

Let’s now answer the question of the article. The reason people can live in just one of these two places is radiation contamination.

Firstly, the amount of radiation released is different. The Little Man bomb released 140 pounds of uranium, while reactor number four had almost 180 tons of uranium.

Secondly, the Little Man detonated in the air, far away from the land. The radioactivity was dispersed in the air, not in the ground. However, 80% of radioactive elements released from the rector went into the ground, where it stays till the current days.

These are the main reasons why people can live in Hiroshima and must avoid the Chernobyl exclusion zone.