Most famously, uranium-238 decays into lead-206 with a half life of 4.5 billion years, though radioactive rubidium and samarium are also useful for dating things billions of years old.

最为有名的就是铀- 238衰变为铅- 206的半衰期为45亿年，当然放射性铷和钐也同样对测算几十亿年前的物体的年龄很有用。

youdao

Now, as you recall from the uranium 238 slide, I think the next slide will show it.

现在，正如你们从铀 238 幻灯片中想起的，我想下一张幻灯片会展示它。

youdao

And if you keep these neutrons from escaping through leakage they then become available to become absorbed in uranium 238.

如果你阻止这些中子通过泄露逃跑，它们之后能够，变成在铀238里能吸收的。

youdao

Although uranium-238 cannot be made to undergo a continuous chain reaction, firing neutrons at it causes some atoms to split, producing a burst of heat.

ECONOMIST: Nuclear power

But fuel rods also contain uranium-238.

ECONOMIST: Nuclear power

The Russians perfected a far less energy-hogging method that uses centrifuges to spin the uranium hexafluoride at 50, 000rpm so that heavier u-238 separates from lighter u-235.

FORBES: Energy & Genius