Electrical Engineering/BWR help

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Question
QUESTION: I do a lot of reading about how BWR work and I do understand a lot.

But just two things I do not understand when I see pictures.

The Core that has the Rods are in Watter and it Heats up I get this.

Now if you look at a Picture of this say on google you see a Pipe going into and going out of the bottom of the Core.

This is the Cooling Watter Pipe.

But am I right that the way this works is when they want to Cool Down the Core the bring Cold Watter into the Pipe and it never leaves the Pipe it just goes into the Core and then Turns around and goes back out?

And it is the Watter making the Pipe cold that cools the Core down?

ANSWER: The core must be kept from overheating. But the purpose of the core is to produce heat; the heat produces steam in the circulating pipes.  The steam is used to run the steam driven electricity generators.  The heat is drawn out of the steam to produce the electric production and cools down the temperature which will become hot again as it circulates through the core.

You can think of the steam pipes as a carrier of the hot energy to the steam generators.

See the following wiki discussion to learn more deeply explained technology:

http://en.wikipedia.org/wiki/Boiling_water_reactor_safety_systems

Hope this will help.



---------- FOLLOW-UP ----------

QUESTION: I tryed to upload a phtot to show you but it say the file may not be the right format or may have the rong charictors.

But I think I have it.


After the water gets Heated the steam goes up and out the top Pipe to get Pumppt to the Turbine to spin and make Electric.

After the steam turns the turbine it gets Conanced and back into water.

Then the cold water pipe you see coming from the cold watter tower goes into the condanced water VAT and loops back out and the pipe has the cold water in it.

And because the pipe is fild with cold water it cols the condanced watter down before it gets pomppt back into the core.

Am  I right?

Answer
Yes, the explanations you will find on the Internet and in text books is an over simplification to describe the basic principles.

In the BWR systems it is necessary to bring out the heat from the nuclear reactor cores.  In so doing the basic principle is to draw off the superheated steam to the steam generators and recycle the steam or condensed steam (water) into the heat core.  But, if the generator is not running at full capacity the draw off may not be sufficient to reduce the temperature sufficiently and the reheating may allow too much heat to get recycled causing temperature run away and even melt down under severe conditions.  Therefore, there are automatic temperature and pressure monitoring systems at work which cool down the vapor or water to the allowable lever before going into the heating core again.  Also, there is always loss of steam or water due to leakage or other conditions that may exist.  The automatic controls inject water back into the system to keep the water/steam level at the ambient conditions necessary for continuous operation.  So, also, it may be necessary to have an auxiliary cooling system to force down the temperature of the steam exiting the generator; these are auxiliary piping of cold water around the steam jackets to keep the temperature down to the correct level to be reheated.

I think the link I sent you explains this process well.

http://en.wikipedia.org/wiki/Boiling_water_reactor_safety_systems

Have a wonderful day.  

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