Some elements such as uranium, commonly used as fuel in nuclear power plants, are always radioactive; there is no nonradioactive form of them that naturally occurs in nature.

一些如铀一般的元素，通常在核电厂用作核燃料，都是有放射性的；这些元素由于自身的性质是没有无放射性状态的。

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The moon contains large concentrations of helium-3, a nonradioactive isotope that's rare on Earth but could be an incredibly valuable fuel for nuclear fusion.

FORBES: Magazine Article

Magnetic, nonradioactive nanoparticles (a tiny fraction of the thickness of a human hair and invisible to the human eye) are injected into the subject, where they bind only to known breast cancer cells within the body.

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