On the other hand, analyses of 85 Kr, a fission product of uranium-235 and plutonium-239, can serve as a means to help verify compliance with the Nuclear Non-Proliferation Treaty.

另一方面，氪-85是铀-235和钋-239的核裂变产物。 对氪-85的同位素含量测定可以用于监督国际核公约的执行情况。

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Nuclear plants use Plutonium-239, which has a chemical half-life of 24, 000 years, meaning anything leaked from Fukushima today will still affect the area for thousands of years to come.

核电站使用的钚239半衰期长达2万4千年，这也就意味着今天从福岛泄漏的物质将在今后几千年内对当地造成影响.

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Nuclear fission can only occur in some types of heavy and unstable nuclei such as in the uranium -235 and plutonium -239.

核裂变只能在某种类型的重核及不稳定核素内发生，如铀- 235及钚- 239。

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In one significant respect U-233 is better than uranium-235 and plutonium-239, because of its higher neutron yield per neutron absorbed.

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From a public health perspective, the most important isotopes are short-lived isotopes of iodine (like Iodine-131), Cesium-137, Strontium-90, and possibly Plutonium-239.

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Each fission reaction splits the nucleus of an atom of uranium-235 or plutonium-239 into two smaller atoms and releases a great deal of energy.

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