how can splitting a tiny piece of an even tinier atom create such a vast explosion?

Question

how can splitting a tiny piece of an even tinier atom create such a vast explosion?

In: Physics

Answer 1

If you have a small piece of uranium, it decays by itself and releases small bursts of energy. That energy is powerful for its size, but it’s not explosive and would not really hurt you unless you spend time with the uranium. And even then, it is cell damage and cancer risk that will hurt you, not an explosion.

When you get to a nuclear reactor, you have a lot of radioactive material with the impurities reduced. The energy released from one of the radioactive atoms causes the atom near it to release its energy. If one atom causes one other atom to release it’s energy, you have a sustained reaction. And one of the side effects is decay heat, which can be harnessed for energy.

Now a reactor can become explosive when one atom sets off more than 1 other atom. Those atoms set off multiple other atoms and now, you have a dramatic increase in heat. Heat causes liquids to turn to gas and causes gases to expand which can cause an explosion. But even then, it’s not really a nuclear explosion per se… It’s an explosion caused by heat build up. (The heat can also set things on fire but those also aren’t really nuclear explosions either. Additionally, nuclear reactors can trigger chemical explosions, like splitting water into hydrogen, which goes boom, but that’s not a nuclear explosion either.)

An intentional nuclear blast is an even more extreme version of this. It requires momentarily packing so many radioactive atoms next to each other in a high energy environment that many of the atoms release their energy all at once: that is, the chain reaction of atoms starts with many atoms going off and they set off many other atoms all at once (like the run away reactor but with a huge starting number of atoms and huge number of nearby atoms set-off by each atom.)

But the main point is the power of a single atom is not explosive per se. Nuclear bombs can only become explosive because many atoms are releasing their bonding energy at once in a chain reaction.