This first atomic pile, built in a squash court at the University of Chicago, used carbon blocks to thermalize neutrons. The first major step was made by Enrico Fermi and his group in December 1942, when they achieved the first self-sustained nuclear reactor. Robert Oppenheimer (1904–1967), whose talent and ambitions made him ideal, was chosen to head the project. It was carried out in remote locations, such as Los Alamos, New Mexico, whenever possible, and eventually came to cost billions of dollars and employ the efforts of more than 100,000 people. The top secret Manhattan Project was a crash program aimed at beating the Germans. It was not until December 6, 1941, the day before the Japanese attack on Pearl Harbor, that the United States made a massive commitment to building a nuclear bomb. It was sent in August of 1939, just before the German invasion of Poland that marked the start of World War II. The letter was for President Franklin Roosevelt, warning of the German potential to build extremely powerful bombs of a new type. Leo Szilard, an escaped Hungarian physicist, took a draft of a letter to Einstein, who, although pacifistic, signed the final version. It was felt that his help was needed to get the American government to make a serious effort at nuclear weapons as a matter of survival. None was more famous or revered than Einstein. It seemed that the military value of uranium had been recognized in Nazi Germany, and that a serious effort to build a nuclear bomb had begun.Īlarmed scientists, many of them who fled Nazi Germany, decided to take action. Within months after the announcement of the discovery of fission, Adolf Hitler banned the export of uranium from newly occupied Czechoslovakia. The enormous energy known to be in nuclei, but considered inaccessible, now seemed to be available on a large scale. The possibility of a self-sustained chain reaction was immediately recognized by leading scientists the world over. Fermi, among others, soon found that not only did neutrons induce fission more neutrons were produced during fission. The discovery of fission, made by two German physicists, Otto Hahn and Fritz Strassman, was quickly verified by two Jewish refugees from Nazi Germany, Lise Meitner and her nephew Otto Frisch. The world was in turmoil when fission was discovered in 1938. Explain the dangers and health impacts of nuclear explosions.Discuss different types of fission and thermonuclear bombs.By the end of this section, you will be able to do the following:
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