In addition, the modular design could make it more difficult to inspect and maintain key components, many of which would be located within the pressure vessel at the heart of the reactor, he said.

CNN: U.S. backs project for small nuclear reactors

The drywell is a large steel pressure vessel that looks like a giant upside-down pear and holds the reactor and primary pumps, and the wetwell is a large toroidal vessel that looks like a donut.

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