The Hidden Horror and Potential of the Atom: Understanding the Nuclear Bomb in Simple Words...

An artistic view of "ATOM BOMB"

A "Nuclear Bomb" or an "Atom Bomb" is a weapon of unimaginable power, created through a process called nuclear fission, where the nucleus of a heavy atom like uranium-235 (²³⁵U) is split apart into fragments to release enormous energy. As a matter of fact, when a single nucleus of ²³⁵U undergoes fission, it produces about 200 Megaelectron Volts (MeV) of energy. This splitting releases more neutrons, which in turn strike nearby uranium nuclei, causing them to split too—creating a self-sustaining chain reaction that multiplies within microseconds.

However, uranium in its natural form mostly consists of uranium-238 (²³⁸U)—about 99.3%, while only 0.7% is uranium-235. This ²³⁵U is the isotope that is capable of sustaining a fast, explosive chain reaction. This is because ²³⁵U has a relatively low fission barrier of about 6.2 MeV, making it easy to split using slow (thermal) neutrons. Typically the thermal neutron have energy of 0.025 eV. In contrast, uranium-238 has a fission barrier of about 7.5 MeV and resists fission unless struck by high-energy neutrons—which are rather harder to maintain in a controlled way. Instead of fissioning, ²³⁸U often captures a neutron and later decays into plutonium-239, which is used in more advanced and dangerous nuclear bombs.

To make uranium useful in a nuclear bomb, it must be enriched to over 90% uranium-235, called weapons-grade uranium. But storing this material safely inside a bomb is tricky. The uranium is split into sub-critical masses, each too small to sustain a chain reaction. These two pieces are kept apart inside the weapon to prevent premature detonation.

When the bomb is triggered, conventional explosives are used to forcefully slam the sub-critical pieces of uranium-235 together. This creates a supercritical mass—a condition in which the amount of fissile material is enough for a rapid, uncontrolled chain reaction. However, for this chain reaction to start precisely at the right moment—neither too early (which would fizzle) nor too late (which would reduce efficiency)—a special device is used: the neutron initiator.

A neutron initiator is a small, specially designed device placed at the center of the fissile core. Its job is to inject a burst of neutrons exactly when the supercritical mass is formed, kickstarting the chain reaction. Without this sudden supply of neutrons, the reaction might begin too slowly, allowing the bomb material to blow apart before releasing its full energy.

In early nuclear weapons, one common type of neutron initiator was based on 210-Po (Polonium) and beryllium (Be). These materials are kept separated inside the device. When the conventional explosives compress the uranium core, they also crush the initiator, forcing polonium and beryllium to mix. Polonium is a strong alpha emitter, and when its alpha particles strike beryllium atoms, neutron emission occurs through the (α, n) reaction: 9Be+α→12C+n. This sudden burst of neutrons seeds the chain reaction at the perfect instant—just as the uranium core reaches supercriticality.

Thanks to the initiator, the reaction begins in a tightly packed, highly compressed core, ensuring that the uranium atoms split in a vast and rapid chain reaction before the core can expand. Within less than a microsecond, this reaction releases energy equal to thousands of tons of TNT, causing the devastating explosion associated with nuclear bombs.

Typically, only 50 to 60 kilograms of uranium-235 is needed for such a bomb—roughly the size of a small watermelon. But the total bomb, with casing (cover) and triggering mechanisms, may weigh to around 4 - 5 tons. For infromation, the “Little Boy” bomb dropped on Hiroshima in 1945 used 64 kilograms of uranium-235. The destruction was apocalyptic. A blinding fireball, hotter than the surface of the sun (over 300,000°C), erupted in the sky. The explosion released energy of around 15 kilotons of TNT. In less than a second, buildings were vaporized, and people closest to the epicenter were reduced to ash. The blast wave flattened structures within several kilometers, while the searing heat ignited fires across the city.

One of the survivors, Setsuko Thurlow, who was a 13-year-old schoolgirl at the time, recalled: “People were desperately crawling out from under collapsed buildings, skin hanging from their arms like rags. The city I knew was gone—turned into burning silence.”

Another, Shigeko Sasamori, said: “I looked at my hands and they were like melting wax. I couldn’t cry. Even the tears had disappeared.”

Over 70,000 people died instantly in Hiroshima, with tens of thousands more succumbing to radiation sickness, burns, and injuries in the weeks that followed. Many survivors lived with lifelong pain—blindness, cancers, deformed limbs, and the trauma of witnessing the unspeakable.

Why Not Use This Power for Good?

It is deeply disturbing that a force capable of such destruction comes from just a few dozen kilograms of metal. But this same atomic power, if harnessed for peacefull purposes, can provide electricity to entire cities. Todays advanced nuclear reactors generate electricity without emitting greenhouse gases, power submarines and spacecraft, and help treat cancer through radiation therapy. Nuclear techniques are used in agriculture, archaeology, water management, and even food preservation.

The atom does not choose its purpose—humans do.

Rather than designing bombs that destroy generations, humanity must focus on harnessing nuclear energy for societal benefits. With responsible policies, transparency, and international cooperation, nuclear science can become a tool for healing, growth, and progress, not horror.

Let Hiroshima and Nagasaki be remembered not just for what was lost, but as warnings of what must never be repeated. The future of nuclear power lies not in fear—but in wisdom, peace, and progress.

To protect humanity from another tragedy like Hiroshima or Nagasaki, we must change our thinking. Instead of using nuclear power for destruction, we should use it for development and peace. The first step is education. People need to learn not only how nuclear energy works, but also how it can be used for good. This includes students, teachers, and especially policymakers.

We should add nuclear education to school books, awareness campaigns, museums, and TV programmes. This will help everyone understand both the dangers and the benefits of atomic energy. If we do this, the public will support peaceful uses of nuclear science.

Nuclear energy can help us in many ways. It can treat cancer, produce clean electricity, power submarines and spacecraft, and help in farming and food preservation. It is a powerful tool—but it depends on how we use it. The atom has no purpose of its own. People must choose to use it for peace, not war.

Traditional universities (AMU, BHU, PU etc.) in India, especially those with long experience and having culture of nuclear science education, should lead this mission. These universities have been teaching and researching nuclear physics for over 70 years. They have trained many of our scientists and experts. Now they can help spread awareness across the country.

They should organize public talks, school programmes, teacher training, and exhibitions. These efforts will help connect scientific research with common people. They will build trust and understanding.

In this way, we can make sure that nuclear science is used for the benefit of all. We must use it to build a better future—not destroy it. Let us remember the past and choose a wiser path forward.

"So friends, nuclear radiation and nuclear energy are not just science—they are the future of sustainable development!"

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