CHAPTER ONE TWO BIG BANGS EVERYTHING OLD IS NEW AGAIN That saying is especially true when it comes to nuclear energy Of all the types of energy that people use today nuclear is both the oldest and the newest The first nuclear reactions likely happened billions of years ago when many scientists think the universe was created in a hot dense state of expansion called the Big Bang But it’s been less than a century since the second big bang when people learned how to generate nuclear energy on their own According to the Big Bang theory the universe burst into particles of energy from a single point in space 6
In the 1800s scientists were studying the idea that all matter consisted of tiny particles called atoms They started to research these atoms how they combined with other atoms and how they moved Some atoms it turned out were more energetic than others Marie Curie was a French-Polish chemist and physicist who noticed that when atoms of elements such as uranium and thorium decayed they changed into other elements and gave off tiny particles of energy in a process called radiation In Britain nuclear physicist Ernest Rutherford speculated that if that energy could be harnessed Some fool in a laboratory might blow up the universe unawares Scientists made great strides toward understanding nuclear energy during the 1920s and 1930s They worked to figure out how to split atoms on purpose This is called fission The nucleus or center of an atom contains protons and neutrons In a fission reaction with a radioactive substance such as uranium extra neutrons bombard the nuclei of its atoms The nuclei become too heavy and unstable and they break apart When these atoms split it frees up the neutrons that were bound inside the nuclei These neutrons then collide with the surrounding uranium atoms in a chain reaction This releases a tremendous amount of energy in the form of heat One atom’s splitting doesn’t provide much energy but many splitting at the same time do Nuclear energy actually comes from billions of fission reactions that happen within a fraction of a second The number of fissions that occur during the explosion of a nuclear bomb numbers more than all the grains of sand in the world Marie Curie’s discoveries made her a pioneer for women in science 7
A cartoon of Leo Szilard demonstrates the tremendous power nuclear scientists were developing Hungarian-American physicist Leo Szilard came up with the concept of a nuclear chain reaction in 1933 According to legend the idea occurred to him as he began walking across a street and he’d figured it out by the time he reached the other side Szilard began experimenting to test his hypothesis What kind of element would work best to achieve a chain reaction He needed one that would be likely to free up neutrons and release energy and thought indium or beryllium might be the answer Neither worked After several attempts Szilard got discouraged and gave up But other scientists believed there was something to Szilard’s idea German chemist Otto Hahn and Austrian physicist Lise Meitner tried their luck with uranium In 1938 Hahn and another German chemist Fritz Strassman showed that the nucleus of a uranium atom would split when bombarded with a neutron and sustain a chain reaction Uranium is incredibly energy-dense A pound of uranium produces almost 4 million times as much energy as the same amount of coal Uranium is a fairly common element It’s found worldwide in mineral deposits and in the ocean Although there’s a lot of uranium it isn’t all useful An isotope is a variation of an element containing a different number of neutrons Uranium-238 8
is a common isotope but it won’t work in nuclear reactions because it is not fissile Fissile means that something breaks apart easily and can sustain a fission chain reaction Uranium-235 is a different story It is fissile But it is also rarer It makes up less than 1 percent of a natural uranium sample Before it can be used as fuel in nuclear reactors uranium must be enriched to increase the amount of U-235 it contains If nuclear energy had been developed 30 years earlier or 30 years later people might use it much differently today But in the heyday of nuclear development the 1930s and 1940s much of the world was engulfed in World War II German scientists had greatly advanced the understanding of nuclear energy and government officials in the United States worried that such knowledge might be used against the Allies In 1942 the U S secretly launched the Manhattan Project with the goal of building a nuclear bomb Within only a few months Italian physicist Enrico Fermi had built the first nuclear reactor in Chicago By 1945 a team of scientists including Fermi and American physicist J Robert Oppenheimer had successfully completed the J Robert Oppenheimer strove to educate others on scientific problems 9
