Nuclear Chain Reaction


  1. This simulation is intended to understand the principle of 'nuclear chain reaction'.
  2. The percentage of models presented may not match the actual.
  3. The nucleus was exaggerated.
  4. The electrons around the nucleus are not represented.

Principles of exponential explosion

When one uranium nucleus is cleaved by a neutron, it produces energy of 2 × 10 8 eV. One TNT molecule produces only 30 eV of energy. It is about 6,600,000 times smaller then uranium nucleus.
After fission, the mass of the byproduct and the mass of the neutron are smaller than the original uranium mass.

Mass before cleavage> Mass after cleavage

The mass is slightly reduced, but it produces enormous energy. This is due to Einstein's famous formula E = mc 2. Some of the energy is used to generate neutrons, and the rest is gamma rays (r-ray).

Scientists have been shocked by this fission. This is because not only does it produce enormous energy but also neutrons. Usually, when one neutron fissures, about two or three neutrons are emitted. If a newly released neutron causes nuclear fission in another nucleus, it will produce 8 to 27 neutrons again, which can cause fission in a chain. That is, a chain reaction occurs at an accelerated rate.

Does fission often occur in nature?

Nuclear fission does not occur in nature. In fact, the chain reaction is only possible in the rare isotope of uranium, 235 U, because only 0.7% of the uranium metal is present. 238 U, which accounts for most of the uranium metal, absorbs neutrons. This makes the chain reaction impossible.

Critical mass

If the fission chain reaction occurs in a small sized mass, the chain reaction will not continue because many neutrons run away from the surface. This is because a small object has a larger surface area than a volume.
There is a minimum size that can cause a chain reaction, which is called the 'critical size', and this mass is called the 'critical mass'.

Atomic bombs use nuclear fission. If it is smaller than the critical mass, it will not explode. To unleash a bomb, you suddenly merge several chunks of 235 U. Then the whole mass explodes suddenly because it is above the critical mass.
(Chemistry - The Central Science)

Nuclear power plants control fission to occur slowly.