Part 2

Ordinary steam power plants depend on fossil fuels--coal, oil, or gas--to make heat. It has been figured out that if only coal were used for fuel, the world's supply would be used up in 350 years. Oil and gas would last for 40 years. But there are enough nuclear fuels to last for at least 8,500 years!

There are several kinds of atomic power plants, but the best known is the Pressurized Water Reactor. This long name is usually abbreviated to PWR.

The PWR isn't really very different from Fermi's pile in Chicago. There is the same big stack of atomic fuel--usually uranium--with control rods sticking out of holes in the fuel bars. Just like Fermi's pile, when the control rods are pushed in they soak up the flying neutrons and there is no reaction. When the control rods are pulled out, the chain reaction takes place.

One of the curious things about a chain reaction is that it won't work if the neutrons are flying too fast. They hit the new atoms at such great speed that they just bounce off and keep going. In order for the neutrons to do their splitting job, they have to be slowed down. Fermi used graphite bricks for this purpose. The PWR uses water, which works very well. And the water also serves another purpose. It absorbs the great heat which is formed in the reactor.

Now, everyone knows that when water is heated to a high temperature, it boils. But _this_ water must not boil. To prevent its boiling, the water is kept under very high pressure, and that is how the Pressurized Water Reactor got its name.

The water is sealed in special tubes and reaches a temperature of about 600° F. The tubes then heat _other_ water which turns into steam.

A simpler kind of atomic power plant is the Boiling Water Reactor, or BWR. The BWR is just a tank which holds a reactor and water. In this case, the water is _not_ under pressure and the heat released by the chain reaction makes it boil. The steam which comes from the boiling water goes directly to the turbine.

Whether they use PWRs or BWRs, atomic power plants don't look very much like ordinary plants. There is no smoke, no dirt, and no fire. Everything is controlled by automatic switches and there may be no more than two or three men in sight.

The first atomic power plant in the world was built in the U.S.S.R. and went into service in 1954. There are now a number of such plants in the United States. Two of the largest are the Duquesne Light Company at Shippingport, Pennsylvania, near Pittsburgh, and Consolidated Edison's Indian Point Plant, in New York State.

Important as atomic power is to cities, it is of even greater importance to faraway places where fuel is hard to get. For example, at the U.S. Army's Camp Century in Greenland, far above the Arctic Circle, obtaining power had always been a problem. The cost of shipping coal or oil to such a place was so high that it was impractical. People had to get along with very little heat or power. But not any more.

Camp Century's new atomic power plant supplies heat and electricity for all. In a whole year the plant uses only 40 pounds of atomic fuel. If it ran on diesel fuel, it would need 850,000 gallons a year!

One of the strangest things about some atomic reactors (called _breeder reactors_), is that they make new fuel as they go along. If the fuel is uranium, it is usually a mixture of uranium-235 and uranium-238. Only the U-235 can be used for the chain reaction. But when the flying neutrons from the U-235 strike the U-238, it turns into a new element, _plutonium_. Plutonium is a fine atomic fuel, just like U-235. In some atomic furnaces there is more fuel at the end of the reaction than the furnace had to start with!

Just look at all the advantages of the atomic power plant: It solves the problem of the disappearing fossil fuels. The plant is almost completely automatic and can be run by just a few men. It saves the cost of shipping heavy fuels to distant places. Some atomic plants make new fuel as they run. Also, the ashes of an atomic furnace are highly valuable for a number of purposes, as you will soon see.

With so many advantages, there is no question that the coal or oil power plant will soon be a thing of the past. It may be that during your lifetime, most of the world's power will come from atomic reactors.

8

ATOMS FOR TRANSPORT

In the year 1819, the world was agog because a steamship had crossed the Atlantic Ocean. How wonderful it seemed! The ship was called the _Savannah_. She carried wood and coal for her steam boilers, but the ship wasn't large enough to carry fuel for the 30-day trip. There was steam for the first seven days, and then the _Savannah_ continued under sails.

Today, there is a new Savannah which can travel for three and one half years on one load of fuel! She is called the Nuclear Ship _Savannah_ and her fuel is uranium. Instead of a steam boiler she has a Pressurized Water Reactor.

The _Savannah_ is a beautiful white ship nearly 600 feet long. But when you look at her, there seems to be something missing. There aren't any smokestacks! Of course there aren't any smokestacks, because there isn't any smoke!

The N.S. _Savannah_ has a speed of 21 knots. She can carry 9,400 tons of cargo, 60 passengers, and a crew of 110. On only 700 pounds of fuel, she can take this heavy load around the world 12 times!

Atomic reactors are already in use on ships and submarines and they may soon be used for other types of transportation. Experiments have been made on atomic tractors which would pull long trains of sleds in the Arctic. And there has been some interest among railroad people in atomic locomotives.

The most serious experiments, so far, with atomic locomotives, have been made in the U.S.S.R. That country, because of its vast size, has an unusual amount of freight traffic. Trains now use up one quarter of all the coal and oil produced there. The Russians have completed the design for an atomic locomotive that will have a speed of 75 miles an hour while pulling a load of 4,000 tons. It will travel for almost a year without new fuel, and will go from Moscow to Riga and back (about 1,000 miles) on a piece of uranium the size of a marble!

Designers here and abroad have also started to think about atomic airplanes. One type of design would use a reactor similar to the power plant reactor. It would make steam, the steam would drive a turbine, and the turbine would turn the propellers.

Another design would work on the turbojet principle and wouldn't need steam. Air would be scooped in and heated by the reactor, then shot out of the rear jets, driving the plane ahead.

However, there are serious problems in designing an atomic plane. One of the hardest to solve is the radioactive exhaust that would come from the reactor. All of the waste products of an atomic furnace are highly radioactive and very dangerous to humans. They can cause serious injury or death. People have to be protected from radioactive materials by heavy shielding of concrete or lead. On a plane, of course, the weight of such a heavy shield would create a difficult problem. The shield would weigh more than the gasoline the atomic fuel replaced.

In time, however, there will probably be a solution to the problem, and atomic planes will be made. There will be no worry about running out of fuel. Such things as head winds, long flights across water, and fuel leaks will no longer be threats to the safety of plane passengers. And when the shielding, problem is solved, instead of carrying 50 tons of gasoline, a big plane will be able to carry 50 tons more of people or cargo.

All of these possibilities are just ideas now. But someday, perhaps, you will chuckle over the old-fashioned days before A-trains and A-planes--or, even A-cars!

9

ATOMS THAT TRACE

Do you remember what isotopes are? They are atoms of the same element, which have different numbers of neutrons in their _nuclei_ (NEWK-lee-eye), the plural of nucleus. Some isotopes, when struck by flying neutrons in a reactor, begin to give off rays, like radium. These isotopes are called _radioisotopes_.

Some radioisotopes are made on purpose by putting certain elements into a reactor. But many radioisotopes are made in all atomic reactors as a natural product of the chain reaction. After the fuel has been used, the radioisotopes are removed from the ashes.

Most elements have at least one radioisotope and many have several. They have thousands of important uses and new ones are found every day.

There are a few properties of radioisotopes which make them useful. One of them is the fact that they give off radiation and so they can always be found with a Geiger (GUY-ger) counter. This is an instrument which ticks when it is struck by an atomic ray. With the help of a counter, radioisotopes can be used as tracers, or tags.

Tracers are used in dozens of interesting ways. One is to find leaks in pipes. Sometimes there is a leaky pipe buried in the floors or walls of a building. How can you find out where the leak is without tearing the building apart? It is very simple. Just add a tiny bit of a radioisotope to the water in the pipe. Then move a Geiger counter along the floor or wall in which the pipe is enclosed. When the ticks stop--or continue, but spread out over a large area--you have found the leak.

A similar trick is often used in the oil industry. Sometimes the same pipeline is used for oil and for gasoline. A worker at the far end of the pipeline has the job of turning off a valve when the oil stops coming through, and turning on a different valve to send the gasoline to the proper tank. But how does he know when the oil is finished and the gasoline is about to start? There's nothing to it. A dash of radioisotope is mixed with the last gallon of oil. The worker keeps his Geiger counter on the pipe. When it begins to tick, it's time to make the change.

If you had a tire factory, how would you find out which kind of rubber gave the best wear? You could make four different kinds of tires and add a bit of radioisotope to the rubber of each. With the tires on a car, instead of driving thousands of miles, as in the past, you could drive just a short distance. As the tires turned, tiny bits of rubber would wear off. A Geiger counter moved over the tire tracks would tell you right away which tire lost the least rubber. Tire companies use this test widely.

Radioisotopes mixed with wax or polish tell how much is left on a car after washing. Radioactive dirt smeared on cloth tells which detergent does the best washing job. If radioisotopes are mixed with the liquid in a tank, a Geiger counter on the outside of the tank can tell where the top of the liquid is. This is much easier than sending a man all the way to the top of the tank to measure the contents with a dip stick.

Scientists have made great use of the radioisotope carbon-14. Carbon-14 occurs naturally in the air and is taken in by all living plants. It is also taken in by all people or animals who eat plants. Once a living thing dies, however, it does not take in any more carbon-14. Now it happens that carbon-14 has a very long half-life--about 5,000 years. So even if a plant or an animal has been dead for 25,000 years, there are still slight traces of carbon-14 left. By measuring the quantity with a counter and comparing it to the quantity in a living plant or animal of the same kind, scientists can tell the age of very old things.

When ancient writings about Biblical times, called the Dead Sea Scrolls, were found, they were wrapped in linen. The linen, made from the fibers of the flax plant, was tested for carbon-14. It was found to be about 2,000 years old. The same method has been used to find the age of ancient wood, leather, cloth, bones--and even mummies!

Radioisotope tracers have been of great benefit to farmers. Mixed with fertilizers, they can be followed with a Geiger counter to see just how the plant uses the fertilizer and how fast. Tracers have shown how certain feeds make animals grow fatter. They help in the study of milk production by cows, egg production by chickens, and growth of wool on sheep.

Perhaps the most important of all tracer uses is in medicine. Radioactive iodine, or iodine-131, is used to find diseases of the thyroid gland. The patient swallows a small dose of the tracer and a counter shows how fast it is taken in by the thyroid gland. This shows how active the gland is. Tracers also help to find brain tumors. And they can be used to follow the circulation of the blood. If an artery is blocked, a person may die because his blood can't circulate. A counter can find the trouble spot and help save a life.

Radioisotopes which are used as medical tracers are not harmful to the body. They are carefully selected to have a very short half-life. Their radioactivity is gone before it can do damage. Also, they are used in tiny quantities.

While radioisotopes do wonderful jobs as tracers, they can do some other very interesting things, too. Let's see what some of them are.

10

ATOMS TO CHANGE ATOMS

When the rays of a radioactive substance strike the atoms of another substance, they may cause changes. We call the exposure to rays _irradiation_ (ir-rade-ee-AY-shun). One of the changes caused by irradiation is called ionization (eye-on-i-ZAY-shun).

Radioisotopes do many important jobs for us by irradiation. In industry, certain petroleum and other materials are changed by irradiation into special fuels, oils, and even synthetic rubber.

Irradiation is used to improve the quality of plastics and to vulcanize rubber. It used to take several hours to vulcanize with heat. A few minutes of irradiation does the same job.

The food industry has begun to experiment with irradiation as a new way to sterilize food. Items which normally spoil quickly, such as hamburger, sausage, cheese, and bread, are exposed to radiation. The rays destroy all of the bacteria that cause food to spoil. The food is immediately sealed in airtight plastic bags. It will remain perfectly fresh for months--or even years. This process may make the canning or freezing of food completely unnecessary.

Even foods which generally keep well, such as onions or potatoes, can be helped by irradiation. The treatment kills any insects that might be in the sack, and also keeps the vegetables from sprouting. A treated potato will keep for a very long time. A number of experiments have been done with potatoes. Before long you will probably see irradiated potatoes for sale in your market.

Irradiation can even improve food crops and other plants while they are still being grown. Changes caused by the rays have already created new and better varieties of corn, peanuts, and oats. The same dose of irradiation works in another way, too--it kills the insects which damage the crops.

Irradiation used in certain medicines can destroy a patient's diseased tissue. Many forms of cancer are treated by this method. In some cases, the patient is injected with a radioisotope. In other cases, he is just exposed to its rays, which are projected from a special machine. Sometimes, tiny bits of isotope, called _seeds_, are actually placed directly in the cancer. Other patients are asked to drink the isotope in a special preparation called a "radioactive cocktail."

Besides their many uses as tracers and irradiators, isotopes have great value as substitutes for expensive X-ray machines. The rays can pass through many materials and, by making a picture on a film underneath, can show differences in thickness or other flaws. Some of the materials that are inspected this way are sheet metal, paper, rubber, and plastics. Also, piston rings for auto engines, and airplane engine valves.

Doctors, too, can use radioisotopes instead of X rays. An X-ray machine is a huge piece of equipment which needs a special room and costs thousands of dollars. A radioisotope machine is about the size of a large can of fruit juice and weighs only ten pounds. It can be carried about easily and is most valuable in an emergency or at a place where there is no X ray available.

These are only some of the things that atoms can do for us. Atomic energy is still young. In the years to come, there will be many changes. During your lifetime, the peaceful atom should make the world an easier, healthier, happier place!

APPENDIX

Some other important atomic pioneers:

Chadwick, James: Discovered the neutron in 1932.

Joliot-Curie, Irene and Frederic: Daughter of Marie and Pierre Curie, and her husband. Were the first to make artificial radioisotopes in 1933.

Rutherford, Ernest: Worked out the nature of radioactivity in 1902, discovered the nucleus of the atom in 1911, and split the first atom in 1919.

Soddy, Frederic: Discovered isotopes in 1910.

Urey, Harold: Discovered hydrogen's heavy isotope, deuterium, in 1932.

GLOSSARY

_AEC_ Atomic Energy Commission (U.S.) All atomic energy in the United States is under the control of the AEC. The Commission is in charge of the sources, manufacture, and uses of all fissionable materials. It has important programs of research, building, training, and information.

_artificial_ A chemical element that does not exist in _element_ nature but which can be made in an atomic reactor.

_atomic_ An atomic reactor. _furnace_

_canal_ A tank of water which is used to hold dangerously radioactive materials in order to protect workers.

_coffin_ A thick metal box which is used to hold very radioactive material.

_contaminated_ Anything that has accidentally become radioactive.

_cool off_ To stop being radioactive. Some materials have to cool off before they can be handled safely.

_critical size_ The smallest amount of atomic fuel that will allow a chain reaction to take place.

_curie_ The unit used to measure radiation. It is equal to the amount of radiation given off by one gram of radium in one second.

_Einstein_, (1879-1955), born in Germany, fled under _Albert_ Hitler, and became an American citizen in 1940. In 1955 he published a brilliant theory which became the basis for the discovery of atomic energy. The theory stated that neither matter nor energy can ever be destroyed, but that matter can be changed into energy. Einstein expressed this in the equation E = mc^2. It means that energy (E) is equal to mass (m) multiplied by the speed of light (c), multiplied by itself. Mass is the amount of material or matter in anything. The speed of light is 186,000 miles a second.

_emit_ To give off. Radioactive substances emit rays.

_enriched_ Ordinary uranium which has fissionable _uranium_ uranium added to it.

_fissionable_ Usable as an atomic fuel. A material whose atoms will split.

_fusion_ A source of atomic energy which is the opposite of fission. Instead of nuclei being split, they are forced together. The energy of the sun is released by fusion.

_hot_ Radioactive.

_moderator_ A material which is used in an atomic reactor to slow down the speed of the neutrons. Graphite and water are common moderators.

_nuclear_ The correct name for energy produced by _energy_ changes in atomic nuclei. _Atomic energy_ is the common name for nuclear energy.

_pig_ Heavy metal container for radioactive material. Similar to _coffin_.

_pitchblende_ The ore richest in uranium.

_remote_ A device that can handle radioactive materials _manipulator_ mechanically while the operator remains safe behind a shield. (Also called a _master slave manipulator_.)

_scram_ To stop an atomic reactor. An emergency stop is called a _fast scram_.

_transmute_ To change one kind of atom into another kind.

INDEX

alpha particle, 30 atomic energy, 8 atomic number, 27 atomic pile, 36 atomic power, 42 atomic theory, 15

Becquerel, Antoine Henri, 20 beta particles, 30 boiling water reactor, 44 breeder reactor, 46

cadmium, 38 carbon-14, 56 chain reaction, 35, 36, 44 chemical compound, 15 Compton. Arthur H., 40 Conant, James B., 40 control rod, 38 Curie, Marie, 22 Curie, Pierre, 22

Dalton, John, 15 Dead Sea Scrolls, 57 decay, 30 Democritus, 13

electron, 26, 29 element, 15 energy, 32

Fermi, Enrico, 36 fission, 34 fossil fuels, 9, 46

gamma rays, 30 Geiger counter, 53 graphite, 36, 44

half-life, 32 helium, 28

Iodine-131, 57 ionization, 60 irradiation, 60 isotopes, 28

neutron, 26, 28 nucleus, 27, 29

pitchblende, 23 plutonium, 46 power plant, 42 pressurized water reactor, 43 proton, 26

radioactivity, 22 radioactive cocktail, 64 radioactive iodine, 57 radioisotope, 52, 64 radium, 23, 30, 32

Roentgen, Wilhelm K., 18

_Savannah_, 48, 49

thorium, 23, 30 tracers, 53

uranium, 20, 29, 30, 32, 43

uranium-234, 29 uranium-235, 29, 46 uranium-238, 29, 46

X rays, 18, 64