core

The nether core reactor has been removed and no longer has a pattern in newer versions.

The core of the reactor contains the nuclear fuel. Having a moderator in place within the core ensures that the nuclear fuel is processed at an accurate time duration. This can prevent serious problems from occurring within the entire nuclear reactor.

Hot gas in a reactor is usually cooled in a heat exchanger adjacent to the core. In gas-cooled reactors, the circulated gas acts as the coolant, and it must be circulated through the core and then out and through an adjacent heat exchanger before being recirculated. In this way, the heat generated by the core can be used in secondary systems and the core can be kept cool. The heat might be for, say, the generation of steam to drive a steam turbine which generates electricity via an attached generator. Gas-cooled reactors were among the original designs offered for reactors, but are still being refined. Use the link below to the Wikipedia post on the advanced gas-cooled reactor and look at the diagram. You'll see the heat exchangers where useful energy can be collected from the circulating main coolant, which is a gas like carbon dioxide or helium.