Reactors

A reactor is a device or system in which a process proceeds by controlled interactions. The term covers technologies in several fields, notably nuclear energy, chemical engineering, and biotechnology, all designed to drive transformations with managed inputs of energy, material, or radiation.

Nuclear reactors use controlled fission to heat a coolant, which transfers heat to a secondary loop that generates steam to drive a turbine and produce electricity. Core components include fuel assemblies, a moderator to slow neutrons, a coolant to remove heat, control rods to regulate the reaction, and a containment to limit releases. Most commercial reactors are light-water reactors, using ordinary water as both coolant and moderator; other designs include heavy-water reactors (using deuterium oxide), gas-cooled reactors, and fast reactors that operate without a moderator. Safety systems provide redundant cooling, shielding, and containment, with regulatory oversight and international guidelines.

Chemical reactors are vessels where chemical reactions occur under controlled temperature, pressure, and mixing. Common configurations include stirred-tank and plug-flow reactors. Bioreactors are used to grow cells or microorganisms for products such as medicines, fuels, or foods, and may control pH, oxygen, and temperature.

History and safety: The first sustained artificial reactor achieved chain reaction in 1942. Since then reactors have expanded for electricity, research, and propulsion. Nuclear safety emphasizes multiple barriers to radioactive release, robust cooling, and defense-in-depth; accidents such as Three Mile Island, Chernobyl, and Fukushima have shaped regulation and public perception.

Outlook: Developments include small modular reactors, advanced fuels, and fusion research. Waste management remains a long-term issue, with strategies such as dry storage and deep geological repositories. Across fields, reactors aim to improve efficiency, safety, and environmental impact.