Which type of reactors are commonly used in U.S. nuclear facilities?

Boiling water and pressurized water reactors are indeed the most commonly used types of reactors in U.S. nuclear facilities. These reactor designs are favored due to their well-established technology, reliability, and efficiency in generating electricity for the power grid.

Boiling water reactors (BWR) utilize water as both a coolant and a heat transfer medium, boiling it to generate steam directly in the reactor core, which then drives a turbine to produce electricity. On the other hand, pressurized water reactors (PWR) keep water under pressure to prevent it from boiling, transferring heat to a secondary system where steam is generated to drive the turbine.

Both reactor types have been extensively tested and have significant operational experience, contributing to their safety and effectiveness. Their widespread adoption in the U.S. nuclear power industry highlights their foundational role in the country's approach to nuclear energy generation, leading to a majority of the nuclear plants operating today being either BWRs or PWRs. This preference is very much in line with the regulatory framework, safety standards, and industrial practices established in the U.S. nuclear sector.