how engineers control power station?

how engineers control powerstations and nuclear reactors ? what kinds of control systems are used in nuclear reactors?

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hemin wrote:

See <http://www.howstuffworks.com/nuclear-power.htm .
That covers the basics. To answer your second point, There are a range of different types of control systems including relay based, PID control, PLC's, DCS and embedded control systems, not to mention the procedural controls as well. As you should appreciate, any nuclear power plant is going to be a very large and complex entity. For any of us to do justice to any of your inquisitive instincts you will need to be asking more specific questions.
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to
Dear Hemin
When you consider the system itself
Its just a heater attached to a steam turbine system
The steam turbine and added generator is a well proven system and there is probably much written on this on the web.
I'd imagine that a very high percentage of the reactor and control rods module is the biggest cost in the system.
Real time control of such a safety critical system is a long winded, expensive process.
I remember being told by my software professor - that no RTsoftware system can be guaranteed as fully safe. Which is a worry.
Multiple sensors measuring the same variable is probably normal - with a layer that identifies the state of the sensor.
Condition monitoring of the system would also probably be normal - Past information with regard to certain failures allows a maintenance schedule that prevents breakdown....minimises downtime.
Much of the control systems for hazardous areas like reactors or oil rigs have standards for every part of the process
There was a situation here in the UK some years ago - when the control system Human Interface on an oil rig gave so many different and varied warnings - that the confused operator was unable to find the problem - Disaster struck.
So the GUI for the system must be easy to understand - this introduces a layer of complex safety considerations
Moving from automatic mode to operator mode is also a big consideration As Paul has said this is a huge area and covers probably every known area of control engineering - so you should be more specific with your questions?
Incidentally
I wonder what standards the Iranian engineers are following?
Setanta
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As you should appreciate, any nuclear power plant is

Complex yes. Large no.
Peter Nachtwey
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On Thu, 11 Jan 2007 22:51:08 -0800, "Peter Nachtwey"

And at it's core is a simplicity necessary for safety. Failsafe taken to it's highest. When this is not true we have disaster.
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Peter Nachtwey wrote:

Are any rated in kilowatts?
Jerry
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Jerry Avins wrote:

The smallest I know of was rated at 6MW (there were four of them on the Sellafield site for a total of 24MW). These are no longer in use. I believe all of the rest are much higher outputs with the most recent installation in the UK being more than 600MW each reactor. Let us also not forget that a power station includes not only the heat source but also a significant turbine driven generator as well. This would make any power station site of this power range seem quite large.
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Paul E. Bennett wrote:

I have been inside one of the Ravenswood alternators when the rotor had been removed. We drove in in a small truck equipped with a bucket lift used to inspect the hydrogen-cooled windings. The plant capacity is now rated over 2,000 MW, but was about 1750 MW when I visited. I assumed than many nuclear plants were of a similar scale.
Jerry
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proclaimed to the world:

The Cassini spacecraft has a reactor.
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Paul M wrote:

Is it a reactor, or a radioactive heat source powering a thermopile?
Jerry
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proclaimed to the world:

Three Radioisotope Thermoelectric Generators -- commonly referred to as RTGs -- provide power for the spacecraft, including the instruments, computers, and radio transmitters on board, attitude thrusters, and reaction wheels.
http://saturn.jpl.nasa.gov/spacecraft/index.cfm
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Paul M wrote:

That's along the lines that I seemed to remember. I won't argue that they aren't reactors of sorts, but I wouldn't refer to them that way.
Jerry
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proclaimed to the world:

Well they don't have a steam cycle.
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Paul M wrote:

A reactor can be many things. You can find things of that name in oil refineries. I think of a *nuclear* reactor as having a moderator and delivering its heat with a circulating fluid, and as "reactor" in this context as meaning "nuclear reactor". I don't know how RTGs work, but those features would surprise me. So I wouldn't call the heat source a reactor despite the reaction evidently going on.
Jerry
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proclaimed to the world:

Hmm. I would define a nuclear reactor as a nuclear reaction harnessed to generate power in whatever form. I have followed Cassni closely. I got involved in sending some letters of support when it was threatened by people worried about the possibility of a launch disaster spreading radiation. I followed it ever since. NASA has been good about disseminating information, even to laymen like myself. Mailing lists are wonderful things. Spam is the scourge of the 21st century. Bah!
Anyway, your definition might be more in line with the actual. Perhaps it should be said that Cassni has a nuclear power plant.
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The following quote are from the howstuffworks article. "The process of capturing the neutron and splitting happens very quickly, on the order of picoseconds (1x10E-12 seconds)."
"When an operator wants the uranium core to produce more heat, the rods are raised out of the uranium bundle. To create less heat, the rods are lowered into the uranium bundle."
Doesn't it bother any body that the reactions happens so quickly and yet the heat is controlled by physically moving rods up and down. This doesn't sound correct. Hmmm.
Peter Nachtwey
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Peter Nachtwey wrote:

There's a lot of thermal mass. That allows one to keep control if there are no lapses and makes it unlikely to regain control if there are.
Jerry
P.S. I had a one-semester course in nuclear engineering in 1960. The only thing I remember from it is that I calculated the minimum diameter of a sphere that would create a thermonuclear bomb from the cross section of fissionable Uranium, using one notebook page. The class met once a week, and I handed the paper to the instructor to ask him where I had gone wrong in making it seem so simple. The following week, he told me that he was not permitted to return my paper because of rules he couldn't talk about. I never learned if he was kidding or serious.
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proclaimed to the world:

Also you can engineer the response by how much carbon is in the reaction material. I can't think of the term for this type of material off the top of my head. Now it is going to bug me.
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<PaulMatWiredogdotcom> says...

It's a "moderator". Soviet reactors like Chernobyl use bricks of graphite as the moderator. US reactors use water.
--Gene
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Gene S. Berkowitz wrote:

So what does the moderator do? So what is the advantage of using wanter?
Peter Nachtwey
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