Despite the fact that it likely contains water and a rocky core, that water is almost certainly in the form of steam or a supercritical fluid.

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The water leak occurred in thousands of tubes that carry heated water from the reactor core through the plant's steam generators.

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Balance is a crucial skill for surfers and one reason that many people who surf do exercises that strengthen the core in their out-of-water workouts.

WSJ: For the Love of Surfing and Wine Country

The enormous heat generated by the radioactive fuel in the reactor core needs a constant flow of cold water.

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These core uses (what they refer to as direct water and steam services in the commercial, residential, industrial and power sectors) eat up 12.3 quadrillion BTU per year.

FORBES: To Conserve Energy - Conserve Water

New rules imposed by the NRC require plant operators to install or improve venting systems to limit core damage in a serious accident and set up sophisticated equipment to monitor water levels in pools of spent nuclear fuel.

NPR: Nuclear Chief: US Plants Safer After Japan Crisis

At Purdue University in Indiana, scientists are working on a reactor-like device that uses water circulated by gravity to keep the core cool.

CNN: Today/Tomorrow - Helping nuclear plants keep their cool