Fisiune

Fisiune is a term used in Romanian to denote the process of division or splitting a system into smaller parts. It is commonly encountered in scientific contexts to describe a fragmentation event where a whole breaks into two or more pieces, often accompanied by energy release or subsequent reactions.

In physics, nuclear fission refers to the process by which a heavy atomic nucleus splits into lighter nuclei, usually after absorbing a neutron. This splitting releases energy and additional neutrons, which can induce further fissions in a chain reaction. Fissile materials such as uranium-235 and plutonium-239 readily undergo fission. In nuclear reactors, the chain reaction is controlled through moderators, control rods, and shielding to manage energy production and neutron economy. The energy released per fission is on the order of 200 MeV, and the fission fragments are typically radioactive, decaying over time into lighter isotopes.

The concept of fission also appears in other disciplines as a general metaphor for splitting. In biology, binary fission describes a simple reproductive method used by some unicellular organisms, where a single cell divides into two daughter cells. In chemistry and materials science, fission-like processes can occur under extreme conditions, leading to fragmentation of molecules or structural units.

Applications and implications of fission are most prominent in energy and security contexts. Nuclear fission powers many terrestrial reactors for electricity generation and has been central to the development of nuclear weapons. Safety, environmental impact, and nonproliferation concerns drive regulatory frameworks, waste management practices, and international oversight. See also: fusion, chain reaction, radioactive decay, nuclear reactor.