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。

youdao

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。

youdao

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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