 In this video, I'm going to use a FET simulation to show you the difference between nuclear fission in a power plant and in a nuclear bomb. First of all, let's quickly review what fission is. In fission, large nucleus splits into smaller ones. In the example here, from the simulation, we have a uranium-235 nucleus that is going to be hit by a neutron at just the right speed to then split up into two smaller nuclei and three neutrons. So we're going to repeat this once more so you can see it again. So the neutron hits the uranium-235, which then becomes unstable, splits into two and releases, upon others, three more neutrons. Now, if that isotope was all alone, not much will happen. However, if we add many more of these isotopes around, what could happen is that one of these neutrons that gets released from the first fission reaction will hit another one and we get what we call a chain reaction. Now, even if you have a couple of them around, chances that the released neutrons hit another one are pretty low. However, if we go above what we call the critical mass, then we will have a chain reaction and all the nuclei will eventually split in a very short time frame and release a lot of energy. So how is this used in a nuclear bomb? Basically, you put more than the critical mass inside the bomb, ideally not at once because otherwise it could go off any moment that there is a neutron at the right speed flying in. So you have to keep them separated somehow initially, but then once you're ready to get up, you put the critical mass together. You make sure there's a neutron going in at the right speed and you have your chain reaction, which will lead to a very violent explosion. Now, it actually sounds quite simple to build the bomb, but it is not as easy as it might sound. First of all, you probably won't find enough isotopes that can be used to be split. The uranium that you would need or the plutonium is not the one that is the most abundant in nature. So if you're mining for uranium, you will actually end up having to enrich uranium to sort out the isotopes that you can actually use for the bomb or the nuclear power plant. This is what we call enrichment. So you maybe have heard in politics people talking about keeping other countries from enriching uranium. This is precisely to prevent them from getting enough material to build the bomb or fuel up a nuclear power plant. The nuclear power plant, the principle is a bit the same. We also want the neutrons from one isotope that splits to hit another one and cause kind of a chain reaction. Unlike the bomb, we don't want everything to go off at once. So we have these control rods here that we can insert in the reactor to keep the neutrons from hitting other isotopes. So the main challenge with the nuclear power plant is to actually keep these control rods at the right position so that we have a reaction continuously going on. But at the same time, the reaction does not go out of control, transforming the reactor basically in a nuclear bomb. So as you see the underlying efficient principle is kind of the same. You start with one isotope that gets hit by a neutron at the right speed. That isotope splits and it's other neutrons, those neutrons hit yet other isotopes. So if you actually can build a nuclear reactor, you probably have the materials that you need to build the atomic bomb. Which is why certain countries do not want some other countries to have access to any form of nuclear technology. Because if you have enough materials to build the nuclear power plant, you probably have enough materials or you can get enough materials to eventually also build the atomic bomb.