Steam generator (nuclear power)

This article is about nuclear power plant equipment. For other uses, see Steam generator (disambiguation).
The inverted U-tube bundle of a Combustion Engineering steam generator.

A steam generator (aka nuclear steam raising plant ('NSRP')) is a heat exchanger used to convert water into steam from heat produced in a nuclear reactor core. It is used in pressurized water reactors (PWRs), between the primary and secondary coolant loops. It is also used in liquid metal cooled reactors (LMRs), pressurized heavy-water reactors (PHWRs), and gas-cooled reactors (GCRs).

In typical PWR designs, the primary coolant is high-purity water, kept under high pressure so it cannot boil. This primary coolant is pumped through the reactor core where it absorbs heat from the fuel rods. It then passes through the steam generator, where it transfers its heat (via conduction through metal) to lower-pressure water which is allowed to boil.