In modern nuclear power plants, what process is primarily used to generate energy?

In modern nuclear power plants, the process used to generate energy is primarily fission. This involves the splitting of heavy atomic nuclei, such as uranium-235 or plutonium-239, into smaller, lighter nuclei when they are bombarded with neutrons. This splitting releases a significant amount of energy in the form of heat, which is then used to produce steam that drives a turbine to generate electricity.

Fission is the dominant process in nuclear reactors because it can produce a large amount of energy from a relatively small amount of fuel. Unlike fusion, which requires extremely high temperatures and pressures and is not yet feasible for practical energy generation in current nuclear technology, fission can be controlled and sustained in a reactor environment.

In contrast, electrolysis involves splitting water into hydrogen and oxygen using electricity, and photovoltaics convert sunlight directly into electricity. While these methods contribute to energy production, they do not relate to the operations of nuclear power plants. Hence, fission appropriately describes the fundamental process that underpins energy generation in modern reactors.