Kyoto – A Perspective (Part 17)

Posted on Sun 04/27/2008 by



Just how then does a Nuclear power plant generate electricity?
This explanation is highly simplified, and for this example, I’ll just deal with the light water reactors.
Remember the picture in the last post showing the blue water inside the reactor. You would have seen some long rods. These rods have the enriched material in them and are bundled together in assemblies and these assemblies are placed inside the Reactor vessel. These rods are in holders and for the reaction, the rods are moved from the holders, this process either removing from or inserting into the core of the reactor, allowing neutrons to be released from the rods to split further atoms of uranium. This process generates extreme heat. This heat then boils water to turn it into steam to drive the turbine which in turn drives the generator.

In simplified form here are the two main types of plants in operation. These diagrams are illustrated on the Nuclear Regulatory Commission’s (NRC) website. You can see there the Pressurised Water Reactor (PWR), and the Boiling Water Reactor (BWR). Under each diagram is a tab that will animate the process when you press on it. You can see from this that the PWR would seem the better option because the Reactor is not open to all of the external water.

Remember how I mentioned an obscure fact that will become important as we discuss other methods. That obscure fact is the efficiency percentage. It may not mean much and detractors will tend to play it down, but it is a really important thing. Why it is important is the fact that a percentage efficiency factor dramatically effects whether or not a method of power production can be used as a base load form of power, and that comes down to the reliability factor, in other words, can the plant produce the power that is needed on a continuous basis to the consumers. The higher the efficiency, the higher the reliability, the better it can be used as base load power.
Where this comes into play is in respect of Wind Power, and Solar power. Let’s use just these three for now, Nuclear, Solar, and Wind methods, all having a maximum power rating of say 500 MW.
With respect to the wind power, the efficiency rating declines somewhat because the wind sometimes does not blow or blows at a variable rate. With respect to Solar power the sun goes down at night for an average of half the time, there are clouds, there’s the cold of winter when the Sun may only be up for limited hours. So at times when the wind is not blowing or the Sun is shining then Maximum power is not being produced. Whereas with nuclear, (along with coal, gas turbines and hydro as well) then the power is always there as long as the fuel source is there.
You might have methods of power that theoretically have the same end figure as maximum power, but if the efficiency factor is low, then it only stands to reason that it cannot be used as base load power.
The efficiency factor for Nuclear power generation approaches 90%, and what that means is that the plant can provide a CONSTANT supply of almost 90% of its maximum rated power all the time, so as a base load supply, it is eminently suitable, so much so that it is the highest efficiency of all methods of power production.

In the last piece I mentioned that there are 104 nuclear Power Plants in the US, but really, only 65 of these are large plants supplying base load electricity on a constant basis. This makes up nearly 20% of the total power generated within the US.

The NRC has safety regulations that make these plants safer than any other of the major plants that generate electricity. That combined with the fact that these plants are clean when they are up and running, and are known to have a long and relatively trouble free life, makes them a viable option, especially in the US.
Something not really mentioned, (an inconvenient truth for those who resist Nuclear Power) is that more radiation is released from coal fired power plants than from Nuclear power plants. You might think this would surely be marginal, if at all, but the ratio is such that coal releases more than 100 times more radiation than an equivalent rated nuclear plant releases.
In the year 1982 when the Three Mile Island incident occurred and radiation was released into the atmosphere, coal fired plants across the US released 150 times that amount into the atmosphere. So even in event of an accident, more radiation is released from coal fired plants overall.

This is a photograph of the Beaver Valley Nuclear Power Plant at Shippingport PA.

The most visible thing at a nuclear power plant are the large cooling towers. Sometimes emotive photographs are shown of these plants with white stuff pouring out the top of these funnels. When you see structures like this you think of chimneys and how smoke comes out of chimneys, and how smoke contains nasty pollution. The white stuff pouring out the top of these structures is nothing more than harmless, and non radioactive, water vapour. When you looked at the interactive pictures above of the two plant types, you would have seen that the turbine is driven by steam boiled by the reaction inside the containment vessel itself. The steam then goes to cooling ponds under these towers. As the steam cools back into water some vapour is given of and in the cool of winter, this vapour is even more visible. So it’s nothing more untoward than a convenient psychological play on your mind.
In the middle of the photograph, you’ll see two small, domed, reinforced concrete structures. These are where the containment vessels for each of the two large turbine/generators are situated, the reactor itself.

These plants are so regulated that safety is of utmost importance.
Besides that, they produce cheap power, and produce no greenhouse gases.

Pennsylvania itself produces around 35% of its total power from nuclear sources, well ahead of the National average of around 20%. Only Illinois produces a greater percentage of power from nuclear sources.
This link shows the Nuclear Power Plants currently in operation in Pennsylvania.

For so long nuclear power has suffered because of that one word, NUCLEAR. In the main people who haven’t bothered to check out just how reliable and how safe it really is have used scare tactics of perceived near misses for an agenda that is not supported by the facts themselves.

For such a technologically advanced Country as the US is, then this option is one that needs to be seriously considered.