Graphite-moderated nuclear reactor

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A graphite-moderated nuclear reactor is a nuclear reactor in which graphite is used as a moderator . The heat can be dissipated either by gas or by water.

The first Chicago Pile 1 reactor built by Enrico Fermi was a graphite-moderated reactor.

Graphite-moderated reactors can be built in such a way that operation with natural uranium is possible. A disadvantage of the graphite-moderated reactor is the flammability of the graphite, which also intensified the effects of the Chernobyl disaster . Graphite-moderated reactors with water cooling like the RBMK have a positive vapor bubble coefficient . This means that if vapor bubbles form in the cooling water, the output increases. As a result, an increase in performance can intensify itself, which can lead to disaster in the event of a fault. Helium-cooled, graphite-moderated nuclear reactors such as the high-temperature reactor are not affected by this risk because of the gaseous coolant.

The graphite-moderated reactors include:

Graphite-moderated reactors are typically larger than light-water reactors because the moderating property of graphite is less pronounced than that of hydrogen.

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