A UI is simply a piece of software that helps a user solve a problem—whether that problem is how to find a book from Amazon.com or how to control a nuclearreactor.
In order to control the nuclear chain reaction, the reactor operators use control rods.
为了控制原子能的连锁反应，反应器的操作人员用到了控制棒。
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In 2009 Mr Proglio suggested that EDF, which is Areva's biggest customer, should take control of the firm's reactor division, to create a fully integrated French nuclear-energy champion.