The nuclear reaction can be controlled utilizing rods made of neutron-absorbing material, such as boron, essentially shutting down the fission process.

核反应可以通过使用由吸附中子的材料构成的棒条，比如硼，来减慢裂变过程，从而控制其反应。

youdao

Nuclear fuel "means any material which is capable of producing energy by a self-sustaining process of nuclear fission and which is used or intended for use in a nuclear ship."

“核燃料”，是指能够通过自身的核裂变过程产生能量，并且被用于或意图用于核动力船舶的任何物质。

youdao

Uranium enrichment is the process used to make fuel for nuclear power plants, but when extended it can also produce fissile material for an atomic bomb.

VOA: standard.2009.11.28

But, in effect, off-shore, outside of Iran, so that this would satisfy the concerns of others like the United States and the Europeans that Iran couldn't secretly use this process to create a stash of what's called fissile material for a nuclear weapon.

NPR: Iran's Response to International Pressure over Nukes