What makes an atom bomb so devastating

Big Bang 8, textbook

72 RG 8.1 / G 8.1 Competence area nuclear physics Summary Nuclear fusion can take place when light atomic nuclei have an extremely high kinetic energy. This is e.g. B. the case at high temperatures. The commercial use of nuclear fusion has so far failed due to technical problems. 46.3 The arsenal of horror nuclear weapons The enormous energy released by fusion or splitting of atomic nuclei can unfortunately also be used to build devastating weapons. Nuclear weapons, also known as nuclear weapons or somewhat sloppily as atomic weapons, get their incredible explosive energy from nuclear fission or nuclear fusion. The core forces play a role here. In conventional explosive weapons, chemical reactions take place in which the atomic nuclei remain unchanged. The electrical forces play a role here. Because these are much smaller, much less energy is released (F8). Fig. 46.18: The Trinity test on July 16, 1945 was the world's first test of a nuclear fission weapon. After 16 / 1000s the fire bubble was already 200m high! Let's start with nuclear fission weapons, that is, the “classic atomic bombs” (Fig. 46.18). They are based on a chain reaction. In principle, you trigger what you absolutely want to prevent in a nuclear power plant, namely an unstoppable nuclear fission reaction with a multiplication factor greater than 1. Take U-235. This releases an average of 2.4 neutrons during nuclear fission. With a small amount of uranium, most of the neutrons reach the outer surface before triggering another fission. The multiplication factor k is then less than 1. If you compare the amount of uranium Z What is the basic mechanism on which all nuclear weapons are based? Why is their effect so devastating compared to conventional explosives? What is the difference between an atomic bomb and a hydrogen bomb? F8 E1 F9 W1 increases, the path of the neutrons to the surface becomes longer. At some point the so-called critical mass is exceeded (Tab. 46.1). Then more than 42% of the neutrons produced trigger a new nuclear fission. Then k> 2.4 * 0.42 = 1, and a chain reaction takes place. This is shown in Fig. 46.3 (p. 67) for a factor k = 2. Isotopes critical mass neutrons are ... not reflected reflected on 30 cm of steel Uranium-235 was used in the Hiroshima bomb. 49.0 kg 17.2 kg plutonium-239 was used in the Nagasaki bomb. 10.0 kg 4.49 kg Table 46.1: Smallest critical masses with spherical shape: If this amount is exceeded, a chain reaction occurs. The construction methods of nuclear fission weapons are different, but the principle is always the same. The fissile material is divided in such a way that it has a subcritical mass (Fig. 46.19). Sure, otherwise the bomb would go off immediately. The parts are shot at one another using conventional explosive devices. The mass becomes supercritical and explodes in a chain reaction. Fig. 46.19: The two only nuclear weapons used in the event of war in comparison (see also Fig. 46.1, p. 67): 100,000 people died immediately as a result of the drops and an additional 130,000 within a few months. The bomb nicknames are therefore more than just cynical. TNT or trinitrotoluene is a common explosive and has been known since the 19th century. In order to be able to compare the explosive power of various bombs, one states how much TNT would have the same effect. One speaks of the TNT equivalent (Table 46.2). With nuclear bombs, incredible energy is released within a very short time. This leads to temperatures of over 100 million Kelvin. In addition, there is a strong pressure wave (Fig. 46.18), direct ionizing radiation and radioactive residues, the fallout. The latter is what makes nuclear weapons particularly dangerous, as this effect is not limited to the moment of the explosion, but can last for years or even thousands of years. For testing purposes only - property of the publisher öbv

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