How Does Nuclear Power Work - Part 2

In the United States, we have two basic kinds of reactors.  These are Pressureized Water Reactors (PWR) and Boiling Water Reactors (BWR).  In a PWR, the reactor is cooled by water that is kept under high pressure to keep it from boiling.  The water is pumped to a steam generator, which is basically as very large heat exchanger.  The primary coolant flows through little tubes which are completely covered by what is typically called the feedwater.  This feed water then gets hot and turns to steam which then makes it way to the turbine.  The turbine blades spin a shaft that is connected to a generator at the other end, providing relative motion between a current carrying conductor and a magnetic field which generates the electricity that powers this laptop.  The steam goes from the turbine to a condenser and is then pumped back to the steam generator.  There are losses along the way which are replenished by water from a nearby water source, either a lake, a river or even a man-made pond.

BWRs differ primarily in the fact that the water boils in the core and the steam goes directly from there to the turbine.  Otherwise the process is the same. 

That one difference leads to others though, such as the fact that BWRs are potentially contaminated throughout the whole system with the entire plant being what is called a radiologically controlled area (RCA).  In a PWR then, there is an extra layer of separation between the fission products in the core and the rest of the world.  Naturally, this is something of an advantage is certain circumstances.  BWRs have the advantage of being cheaper and easier to run due to the fewer number of systems that need to be maintained.

Now, what I said about BWRs sounds bad from a radiation standpoint.  In our next installment we’ll take a quick