They were exposed to radioactive fallout during nuclear weapons tests.

他们在核武器试验过程中暴露于放射性核辐射。

《柯林斯英汉双解大词典》

The phenomenon is called radioactive fallout.

这一现象即称之为放射性尘降。

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On the other hand, the radioactive fallout at the plant keeps mounting.

另一方面，核电厂的放射性沉降物不断聚集。

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The biggest hazard of atmospheric tests was that radioactive fallout would get into the human food chain.

CNN: ASIANOW - Asiaweek

This could trigger a full-scale war, with missile attacks, radioactive fallout, economic turmoil and massive refugee flows.

CNN: North Korea: What are the options?

The UK charity Chernobyl Children's Life Line helps families in Ukraine and neighbouring Belarus affected by harmful radioactive fallout.

BBC: Inverness and Nairn charities host Chernobyl events