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Nothing Magical about Nuclear

May 31, 2011

There’s nothing magical about nuclear power. Nuclear is just another way to boil water to produce steam.

From the beginnings of the industrial revolution, steam has been the substance that powered engines. Later, combustible-fuels were used to power internal combustion engines.

Watt’s steam engine injected steam above a piston so that it would force the piston down as the steam expanded. (Earlier designs relied on a vacuum to pull the piston down.) The depleted steam would be removed, using a vacuum, and the piston would be returned to its starting position. Steam would again be injected above the piston and the cycle would be repeated.

Further development used a slide valve that would allow steam to be injected above the piston, and then below the piston after it reached the bottom of the cylinder. The used steam in the top of the cylinder would be evacuated from the top as steam entered the bottom of the cylinder and forced the piston upward. These actions would be repeated, sequentially so that the piston would move in both directions. (The motion could be sideways, as well as up and down.)

Another approach was to build a series of pistons and cylinders so that steam from the first piston would be used to drive the second piston and then the exhaust steam from the second would be used to drive the third piston. Each piston would become progressively larger as the steam expanded. This was referred to as a triple expansion steam engine and it was still being used during the Second World War to power Liberty Ships.

The first Edison power plants used reciprocating steam engines that would be connected, through a crank shaft that converted the reciprocating motion to rotary motion, to a generator to generate electricity.

Along the way, steam was used to drive turbines. The steam would be injected into a row of buckets mounted on a shaft which would impart a rotary motion to the shaft. As the steam expanded it would be introduced sequentially into multiple rows of buckets. Each row of buckets would use the expanding steam to extract energy from the steam and impart additional force to the rotating shaft. Each row of buckets would become larger as the steam expanded. As the steam left the last stage of buckets, it would enter a condenser under vacuum.

The internal combustion engine worked the same way as the reciprocating steam engine, except a fuel would be ignited in the cylinder above the piston, where the exploding fuel would expand and force the piston down. The spent fuel would be removed through an exhaust and the cycle would be repeated. Multiple pistons would be used to drive a crankshaft that converted reciprocating motion to rotary motion.

The gas turbine uses natural gas, or other volatile fuels, which are ignited in combustion chambers where the expanding gas is injected into a row of buckets, in the same manner that steam is injected into a steam turbine. As the gas expands, it flows through multiple rows of buckets, much the same way steam flows through a steam turbine.

Both the internal combustion engine (ICE) and gas turbine require a source of air which must enter the cylinder of the ICE or the combustion chamber of a gas turbine. A turbo-charger can force extra air into the ICE’s cylinders while a compressor mounted on the shaft of a gas turbine forces air into the combustion chambers.

In a coal-fired power plant, coal is burned in a boiler to produce steam that is then injected into a steam turbine. The higher the temperature and pressure of the steam, the more efficient the coal-fired power plant will be.

A nuclear power plant uses the nuclear reactor to produce steam. The steam is then used to drive a steam turbine generator.

The nuclear reactor could use a fluid other than water and convert it to a vapor that would drive a turbine the same as would steam. (This shouldn’t be confused with a gas turbine where the gas is ignited in combustion chambers.)

This brings us to concentrating solar power where, using mirrors, sunlight is focused on a heat exchanger that converts a fluid to a vapor that then drives a turbine.

In a similar manner, a geothermal power plant uses the heat from the geothermal area to produce a vapor that drives a turbine to generate electricity.

These describe the fundamental ways in which electricity is generated, other than PV-Solar, Wind or Hydro. In each of the methods described above, heat is converted to mechanical energy to drive a generator.

When viewed this way, nuclear is merely another way to boil water.

Assuming each method is safe, the issue remains: Which method produces electricity at the lowest cost?

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 Additional TSAugust web sites:

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 [To find earlier articles, click on the name of the preceding month below the calendar to display a list of articles published in that month. Continue clicking on the name of the preceding month to display articles published in prior months.]


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