How do you write a topic sentence that supports nuclear energy?

In order to write a good topic sentence, the first thing
you need to know is what you are going to say on the topic.  You have to do this first
-- you can't write a good topic sentence if you don't know what your argument will
be.

So, imagine that you are going to say that nuclear
energy is a good idea for economic reasons.  Your topic sentence could say "With the
rising price of oil, there is a need for more economical sources of energy such as
nuclear power."

Now imagine that you want to promote
nuclear energy for environmental reasons.  You could then say "Although many people fear
nuclear energy, it is much better for our environment than fossil fuels
are."

Or if you intend to talk about both reason, you could
say "Nuclear energy is superior to fossil fuels because it can save our economy money
while reducing emissions of greenhouse gases that cause global
warming."

In all of these cases, you are telling the basic
idea of what you are going to argue.  That is the main thing that you must do in a topic
sentence.