Two types of nuclear reactors

U.S. Nuclear Regulatory Commission
 

Pressurized Water Reactors

Pressurized Water Reactors are known as “PWRs.” They keep water under pressure so that it heats but does not boil. Water from the reactor and the water that is turned into steam are in separate pipes and never mix.

 

 

Boiling Water Reactors

Boiling Water Reactors are known as “BWRs.” In BWRs, the water heated by fission actually boils and turns into steam to turn the generator. In both types of plants, the steam is turned back into water and can be used again in the process.