Helium is the by product of millennia of radioactive decay from the elements thorium and uranium.

氦是钍和铀元素数千年放射性衰变的副产品。

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NUCLEAR power does not emit greenhouse gases, but the technology does have another rather nasty by-product: radioactive waste.

核能发电不会排放温室气体，然而这项技术的确存在另一个不好对付的副产品：放射性核废水。

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These teeth were then tested to determine their level of Strontium-90, a radioactive fission product that escapes in nuclear power plant emissions.

这些乳牙都要经过测试，以确定它们的锶- 90的积存程度。锶- 90是一种核裂变的产品，它们会从核电站的排放物中逃逸和扩散。

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The health ministry says no food or drink product will be permitted to be sold if it has radioactive cesium above the government-set limit.

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