The Power of the Atom

Nuclear Power's Remarkable Energy

Nuclear energy may be the greatest scientific discovery of the 20th century. It is based on physics of the atom, which is the reason a large portion of the public does not yet understand it. It is difficult to grasp how an energy source can be so powerful and still have so little impact on the environment. Yet if we were to describe the ideal energy source - low fuel requirements, no carbon emissions or other pollution, little land requirements, low cost, and large amounts of power - it would be nuclear energy.


Splitting a uranium atom yields two million times as much energy as breaking the carbon-hydrogen bond in coal. That means a few uranium fuel rods can produce the same amount of power as whole trainloads of coal. In fact, the traces of uranium in coal is about 0.03 percent of its weight which actually contoin more potential energy than the coal itself. Instead of burning coal, it would be much better to mine it for uranium.


Low energy density is an even bigger problem when we come to renewable resources. What we are calling renewables are actually energy flows in nature, with far lower density than fossil fuels. Biofuels, for example, have about 1/4 to 1/10 the density of coal because they are young coal that has not compacted and ages in the earth for millions of years. Wind and solar are limited by the density of air and energy content of sunlight, which are sunstantial over vast areas, but are relatively weak on the scales of traditional energy sources. Only geothermal energy has a high sensity and that is because it is actually nuclear power emanating from deep within the Earth. The breakdown of uranium and thorium deep in the Earth, combined with the pressure of gravity, raises the temperature at the center of the Earth to 7000 degrees Celcius, hotter than the surface of the sun. When we build a nuclear plant, we are simply borrowing some of the Earth'd natural heat and putting it in the controlles environment of a reactor. Nuclear power and geothermal power are essentially the same thing.


Energy density becomes hugely important when it comes to mining and transporting these fuels and disposing of their waste. A 1000 megawatt coal plant is fed by a 110 car freight train arriving every 30 hours, 300 times a year. In one year the plant will throw 10 million tons of carbon dioxide into the atmosphere. Whole mountainsare being decapitated and mile wide holes dug in the ground in Wyoming or Montana to mine this coal. When sulfur and ash are removed by scrubbing, large reservoirs of sludge are produces that are a disposal problem in themselves. Yet this effort to clean coal of its pollutants will pale beside any attempt to capture carbon dioxide, the prime waste product and store it in underground caverns. Carbon capture and sequestration will be the biggest engineering job ever attempted on the planet.



 Now compare this to nuclear technology. A nuclear reactor is refueled when a half dozen tractor trailers arrive at the plant carrying new fuel rods once every 18-24 months. The rods are only mildly radioactive and can be safely handled with gloves. They will sit in the reactor for five years, producing no pollution or carbon emissions. When removed five years later, they will look exactly the same, just like a bundle of metal pipes except now they are radioactive. A few feet of lead or water blocks all radiation, however, so they can be stored safely in pools or lead lined casks. Within three years they will lose half their radioactivity. After that, nuclear reprocessing can recycle mosy of the soent fuel rod into new fuel. Only 3 percent of the energy potential of a fuel rod is used in its first run-through.


It is this off the scale energy potential thats makes nuclear energy so hard ti understand and the subjects of so much fearful speculation. When the uranium atom splits in 2, about one billionth of its mass is completely transformed into energy. Yet because of Einstein's famous equation, E = mc², this tiny amount of matter converts into one quadrillion times as much enegy. A uranium fuel pellet the size of a thimble contains the energy equivalent of 1780 pounds of coal, 149 gallons of oil, or 17000 cubic feet of natural gas. After a fuel assembly completes its five year cycle, only six ounces of the mass will have been completely converted into energy. Yet this energy will be enough to power a city teh size of San Franvisco for those five years.

Comparison to Fossil Fuels and Renewables 

Wind, solar and other renewables have energy densities that are incomparably smaller. Therefore their land requirements are stupendously larger. While a 1000 megawatt nuclear reactor is powered by a fuel assembly that would fit into an average sized living room, a 1000 megawatt hydroelectric plant requires a reservoir 250 miles square. This is the reason environmentalists began opposing dam construction in the 1960s because they took up so much space. Wind has less density and wind farms will have to cover 270 square miles to generate the same 1000 MW of reliable electricity. Burning biomass to generate electricity will require about 800000 acres of continuosly farmed grassland or forest to generate 1000MW. And any effort to harness the tides or ocean currents will face the same limitations. About 25 miles of coastline will be required to produce 1000MW.

 Solar energy radiates from nuclear reactions in the Sun, but they occur 90 million miles away and are very dilute by the time they reach the Earth. Solar energy gives us about 400 watts per square meter. Since the best technologies can convert only 25% of this to electricity, solar can give us one 100 watt bulb per average card table. This is a significant amont of energy. We should do everything we can to take advatage of it. Covering every square inch of the rooftop in the country with solar collectors could probably provide enough power to run our indoor lighting and some household appliances during daylight hours.


Solar electricity's great advantages is that it peaks during the hottest hours of the day and on summer afternoons, when customers are running their air conditioning and utility companies are straining to meet peak demand for power. Solar electricity would be ideal for meeting peak demand, now handled mostly by expensive gas turbines.


The problem arise when overenthusiastic supporters of solar and wind energy argue it can be used to meet nase loads. Solar and wind electricity is ill suited to provide base load power, which must run uninterrupted night and day as electricity from solar and wind can't be stored still. Without some way to stored large amounts of electricity, there's no way to have more than 25% of our electricity being provided by solar and wind.


For all these reasons, reducing carbon emissions will mean building nuclear plants to provide base load electricity until carbon capture and sequestration, or some other technology can be developed to capture emissions from coal plants or until some unforeseen technological development makes it possible to use sun and wind for base load. Right now these alternatives are too uncertain and expensive. Only nuclear power offers the potential for reducing our impact on the environment, resolving the problem of climate cahnge while producing large amounts of cheap, clean and reliable electricity. The potential is there. We only have to address the inreasonable fears surrounding nuclear energy.