Light Water Reactars (LWR) are nuclear reactors

The light-water reactor (LWR) is a type of thermal-neutron reactor that uses ordinary water, as opposed to heavy water, as both its coolant and neutron moderator.

Key Points

• The water serves the dual purpose of cooling the reactor core and slowing down the neutrons produced during nuclear fission reactions, making them more likely to induce further fission.
• This enables a self-sustaining chain reaction and helps regulate the nuclear reactions within the reactor core.
• The most common types of LWRs are Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR).

Thus, LWRs are a type of nuclear reactor that uses regular or ordinary water as both a coolant and a moderator.