In the fission reactions that nuclear power generation relies on today, heavy elements such as uranium break into smaller ones, while in nuclear fusion small elements such as hydrogen stick together and form heavier elements (helium). Both fission and fusion produce a lot of energy.
在我们今天用来产生核能的核裂变反应中，是把铀这样的重元素裂变成小的元素，而核聚变是把像氢这样的小元素结合在一起形成重元素（氦）。核裂变和核聚变都能产生巨大的能量。