Here is an improved version of the introduction section for your Fission page, fixing minor typos and grammatical errors (such as "As well producing", "can be under uncontrolled", and "then the discussing physics principles") to make the writing smooth and polished:

When thinking about nuclear processes, we have primarily focused on radioactive decay—namely alpha, beta, and gamma decay.

Along with producing decay products, these reactions release energy. However, other nuclear processes also release significant amounts of energy without involving spontaneous radioactive decay:

• Fission: A process in which a heavy nucleus splits into two smaller, lighter nuclei, releasing energy in the process.
• Fusion: A process where two light nuclei combine to form a heavier nucleus, also releasing excess energy.

In both cases, reactions can occur in an uncontrolled manner, releasing energy almost instantaneously, or in a controlled manner, allowing energy to be harvested progressively over time.

Understanding Nuclear Fission

We will start with fission, which generates energy when a large, heavy nucleus splits into two smaller daughter nuclei. The combined mass of the resulting fragments is slightly less than the initial mass of the parent nucleus; this mass defect is directly converted into energy via E =Δmc^2.

The video below examines fission from both a historical perspective and through core physics principles. (Note: Make sure you have a solid understanding of mass defect and binding energy before watching.)

How a nuclear reactor works

How a Nuclear Reactor Works

At its core, a nuclear reactor harnesses nuclear fission by maintaining a controlled chain reaction. Because the fission rate depends directly on the number and kinetic energy (speed) of available neutrons, a reactor regulates power output by controlling both neutron population and neutron velocity.

Although modern nuclear reactors are complex engineering systems, they all operate on the same fundamental physics principles. The video below breaks down the key components of a typical nuclear reactor, including fuel rods, moderators, control rods, and coolant systems.