By Earl Hunsinger
Nuclear power is considered by many to be complicated and dangerous. The use of radioactive materials certainly has the potential to be dangerous. The radioactive waste produced by this use is even more potentially dangerous, if only because of the need for safe, long term storage. However, as far as being complicated, nuclear power plants are only complicated because of the redundant safety measures used. Many people would probably be surprised to learn that in itself the generation of power from radioactive materials (uranium) is not complicated at all. In many ways it is simpler than burning coal. The very name given to the nuclear material used implies this simplicity. The uranium at the heart of the power plant, the nuclear reactor, is often called a nuclear pile. The history of the first nuclear pile illustrates why this is so, along with the simplicity of this most feared source of power.
On September 12, 1933, the famous physicist Lord Rutherford was quoted in The Times of London as saying that anyone that looked to the atom as a potential source of power was "talking moonshine." As the Hungarian theoretical physicist Leo Szilard later said, "Pronouncements of experts to the effect that something cannot be done have always irritated me." As a consequence, as Szilard stopped on a street corner in London’s Southampton Row waiting for the light to change, he was thinking of how Rutherford might be proved wrong. As the light changed to green and he began to walk across the street, he realized that the solution was to find an element that would be split when struck by neutrons and would release two neutrons for every neutron that it absorbed. With a large enough quantity of this element a chain reaction could be created, with two neutrons becoming four, four becoming eight, and so on. This simple, yet profound insight, would lead to nuclear power plants, and their more sinister cousins, atomic bombs.
Eventually, it was discovered that uranium could be used to sustain the type of chain reaction that Szilard had envisioned. By 1942, the world was engulfed in war and the Manhattan Project had begun. The scientists working on this top secret scientific project had been charged with the task of building the world’s first atomic bomb. As part of this work, the Italian immigrant and physicist Enrico Fermi was leading a group of scientists (including Leo Szilard) in the construction of the world’s first nuclear reactor. The site chosen for the experiment was a squash court under the football field at the University of Chicago. Blocks of graphite and uranium were laid in a circular pattern on the floor of the court. The plan was to stack these blocks so that they eventually formed a sphere (literally a pile) with a radius of approximately thirteen feet. Cadmium rods were added as the blocks were stacked. These would absorb neutrons and so stop the chain reaction.
According to the University of Chicago website, when the last of the cadmium coated rods was withdrawn at 3:25 pm on December 2, 1942, the world’s first self sustaining nuclear chain reaction was initiated.
The world’s first nuclear pile had very few safety devices. The book The Making of the Atomic Bomb, by Richard Rhodes, estimated that if the scientists present on that day had allowed the chain reaction to continue for an hour and a half, the reactor would have reached a million kilowatts. Long before that it would have killed them all and melted down. One of the only safety systems that they employed consisted of the spare cadmium rods suspended over the pile of uranium by a rope, with a man standing by the rope with an axe, ready to cut it if things got out of control. According to Paul W. Frame of the Oak Ridge Associated Universities, the nuclear safety term SCRAM, which refers to the sudden shutdown of a reactor, pays homage to this man. SCRAM is said to stand for "safety control rod axe man."
Present day nuclear reactors are much more than just a pile of nuclear and graphite bricks. Steam is produced from the heat generated by the chain reaction. This steam is used to turn turbines, which are used to generate electricity. Extensive shielding is built around the radioactive material and elaborate safety and control systems are installed. Still, as complicated as these systems are, the basic principle remains the same as it was way back then in that squash court. Uranium is stacked up to form a "nuclear pile."
For more technical information about the first chain reaction, please see the website Chemcases.com
Nuclear Weapons
Information on nuclear weapons design, production, materials, testing and effects both historic and current. Includes diagrams and explanations of the ...
Nuclear power is considered by many to be complicated and dangerous. The use of radioactive materials certainly has the potential to be dangerous. The radioactive waste produced by this use is even more potentially dangerous, if only because of the need for safe, long term storage. However, as far as being complicated, nuclear power plants are only complicated because of the redundant safety measures used. Many people would probably be surprised to learn that in itself the generation of power from radioactive materials (uranium) is not complicated at all. In many ways it is simpler than burning coal. The very name given to the nuclear material used implies this simplicity. The uranium at the heart of the power plant, the nuclear reactor, is often called a nuclear pile. The history of the first nuclear pile illustrates why this is so, along with the simplicity of this most feared source of power.
On September 12, 1933, the famous physicist Lord Rutherford was quoted in The Times of London as saying that anyone that looked to the atom as a potential source of power was "talking moonshine." As the Hungarian theoretical physicist Leo Szilard later said, "Pronouncements of experts to the effect that something cannot be done have always irritated me." As a consequence, as Szilard stopped on a street corner in London’s Southampton Row waiting for the light to change, he was thinking of how Rutherford might be proved wrong. As the light changed to green and he began to walk across the street, he realized that the solution was to find an element that would be split when struck by neutrons and would release two neutrons for every neutron that it absorbed. With a large enough quantity of this element a chain reaction could be created, with two neutrons becoming four, four becoming eight, and so on. This simple, yet profound insight, would lead to nuclear power plants, and their more sinister cousins, atomic bombs.
Eventually, it was discovered that uranium could be used to sustain the type of chain reaction that Szilard had envisioned. By 1942, the world was engulfed in war and the Manhattan Project had begun. The scientists working on this top secret scientific project had been charged with the task of building the world’s first atomic bomb. As part of this work, the Italian immigrant and physicist Enrico Fermi was leading a group of scientists (including Leo Szilard) in the construction of the world’s first nuclear reactor. The site chosen for the experiment was a squash court under the football field at the University of Chicago. Blocks of graphite and uranium were laid in a circular pattern on the floor of the court. The plan was to stack these blocks so that they eventually formed a sphere (literally a pile) with a radius of approximately thirteen feet. Cadmium rods were added as the blocks were stacked. These would absorb neutrons and so stop the chain reaction.
According to the University of Chicago website, when the last of the cadmium coated rods was withdrawn at 3:25 pm on December 2, 1942, the world’s first self sustaining nuclear chain reaction was initiated.
The world’s first nuclear pile had very few safety devices. The book The Making of the Atomic Bomb, by Richard Rhodes, estimated that if the scientists present on that day had allowed the chain reaction to continue for an hour and a half, the reactor would have reached a million kilowatts. Long before that it would have killed them all and melted down. One of the only safety systems that they employed consisted of the spare cadmium rods suspended over the pile of uranium by a rope, with a man standing by the rope with an axe, ready to cut it if things got out of control. According to Paul W. Frame of the Oak Ridge Associated Universities, the nuclear safety term SCRAM, which refers to the sudden shutdown of a reactor, pays homage to this man. SCRAM is said to stand for "safety control rod axe man."
Present day nuclear reactors are much more than just a pile of nuclear and graphite bricks. Steam is produced from the heat generated by the chain reaction. This steam is used to turn turbines, which are used to generate electricity. Extensive shielding is built around the radioactive material and elaborate safety and control systems are installed. Still, as complicated as these systems are, the basic principle remains the same as it was way back then in that squash court. Uranium is stacked up to form a "nuclear pile."
For more technical information about the first chain reaction, please see the website Chemcases.com
Nuclear Weapons
Information on nuclear weapons design, production, materials, testing and effects both historic and current. Includes diagrams and explanations of the ...
