Kevytvesireaktorien

Kevytvesireaktorit, often abbreviated as LWRs, represent the most common type of nuclear reactor used worldwide for electricity generation. They utilize ordinary water, also known as light water, as both a neutron moderator and a coolant. This design choice makes them simpler and more cost-effective compared to reactors employing heavy water or other exotic coolants.

There are two primary types of light water reactors: the Pressurized Water Reactor (PWR) and the Boiling Water Reactor (BWR). In a PWR, the water coolant is kept under high pressure to prevent it from boiling within the reactor core. This superheated water then flows to a steam generator, where it transfers its heat to a separate loop of water, producing steam to drive a turbine. In contrast, a BWR allows the coolant water to boil directly within the reactor core. The steam generated then flows directly to the turbine.

LWRs typically use enriched uranium as fuel, where the concentration of the fissile isotope uranium-235 is increased above its natural abundance. The fission process within the fuel rods generates heat, which is then transferred by the light water coolant. The control rods, typically made of neutron-absorbing materials like cadmium or boron, are used to regulate the nuclear reaction rate by being inserted or withdrawn from the core.

Safety features are a paramount concern in LWR design. Multiple redundant safety systems, including emergency core cooling systems, are incorporated to manage potential accidents and ensure the integrity of the reactor core. The extensive operating experience and established safety record have contributed to the widespread adoption of light water reactors in the global nuclear energy landscape.