unstable nuclear的意思|示意

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。

This causes a drop in pressure that makes the star unstable and causes it to contract under its own weight. Eventually the process ignites runaway nuclear reactions that rip the star apart.

这引会起压强的突降，使得恒星不稳定并在自己的重力下收缩。最终这个过程引发了雪崩式的核反应并将恒星斯裂开。

With Japan's reactors still unstable, it may be difficult to be rational about nuclear energy.

日本的反应堆还没有稳定，对核电很难理性地去评判。