Atomic bomb number

The rapid fission of a mass of or another heavy nucleus is the principle of the atomic bomb, the energy liberated being the destructive power. For useful energy the reaction has to be moderated this is done in a reactor where moderators such as water, heavy water, graphite, beryllium, etc., reduce the number of neutrons and slow those present to the most useful energies. The heat produced in a reactor is removed by normal heat-exchange methods. The neutrons in a reactor may be used for the formation of new isotopes, e.g. the transuranic elements, further fissile materials ( °Pu from or of the... 

This is a technique developed during World War II for simulating stochastic physical processes, specifically, neutron transport in atomic bomb design. Its name comes from its resemblance to gambling. Each of the random variables in a relationship is represented by a distribution (Section 2.5). A random number generator picks a number from the distribution with a probability proportional to the pdf. After physical weighting the random numbers for each of the stochastic variables, the relationship is calculated to find the value of the independent variable (top event if a fault tree) for this particular combination of dependent variables (e.g.. components). 

The British aircraft industry appeared to be backward compared with its American and Soviet counterparts, but this was mainly because the expectation that the maximum danger of war lay in the future, about 1957, led to a gap in British development and production of a number of important weapons systems. The timing of up-to-date strategic bombers was linked to the development of the British atomic bomb, which, although first tested in October 1952, would not be ready for operational use until about 1956. Meanwhile Britain was wholly dependent on the United States for nuclear deterrence. 

It can be seen that the mass numbers on either side of the equation add up to the same number, 238, and that 92 protons are accounted for in the equation s product and reactant sides. This is a balanced nuclear equation. Actually, some mass is converted into energy, but the amount of mass is very small. From Albert Einstein s equation, E = me2, very little mass, m, is needed to produce a tremendous amount of energy, E, because c is the speed of light, 3 x 108 m/sec. This energy was evidenced when an atomic bomb was exploded over Hiroshima, Japan, during World War II. The fuel for that bomb was uranium-235. 

In addition to the huge amount of energy released by nuclear fission reactions, another important result of such reactions is that more neutrons are produced than the number of neutrons used to bombard. The produced neutrons may also strike other 235(J isotopes and causes new fissions. The new nuclear fission reactions also produce neutrons with huge amounts of energy, and so on. This continuous process is said to be the atomic bomb, and is the basic principle of nuclear reactors. 

The second atomic bomb was dropped on Nagasaki on August 9, 1945. In this occasion, the number of dead was not so high as in Hiroshima because the people in Nagasaki had been warned previously. However, diseases and deaths from nuclear radiation have continued ever since August 15, 1945. 

The lanthanide and actinide elements are located at the bottom of the periodic table in two rows separate from the rest of the elements. By atomic number, they should be located in Periods 6 and 7, but they have special properties that distinguish them from elements in those periods. Lanthanides are very similar to each other and have some industrial uses. Many of the actinides were discovered as part of the first atomic bomb experiments. They are highly radioactive and have few uses. The transuranium elements were mostly created in the laboratory and are very short-lived. 

When a neutron enters a sample of 92U, it may collide with the nucleus of one of the atoms, producing a reaction in which two or three new neutrons are produced. Each of these may react with another nucleus, producing more reactions and an increased number of neutrons (Figure 21.5). Such reactions, all started by a single neutron, can continue until the entire sample of has reacted. The sequence of reactions is called a chain reaction and is the source of energy by which nuclear power plants operate. The atomic bomb, which should more accurately be called the nuclear bomb, also uses a chain reaction. 

This reaction is an example of a nuclear chain reaction, in which the products of the reaction cause more of the same reaction to proceed. The three neutrons can, if they do not escape from the sample first, cause three more such reactions. The nine neutrons produced from these reactions can cause nine more such reactions, and so forth. Soon, a huge number of nuclei are converted, and simultaneously a small amount of matter is converted to a great deal of energy. Atomic bombs and nuclear energy plants both run on this principle. 

Through fission, neutrons of low energy can trigger off a very large energy release. With the imminent threat of war in 1939, a number of scientists began to consider the possibility that a new and very powerful atomic bomb could be built from uranium. Also, they speculat-... 

In 1940, American physicists Edwin McMillan (1907—1991) and Philip Abelson (1913—2004) discovered the first transuranium element, neptunium (atomic number 93). The neptunium they produced was radioactive. They predicted it would break down to form a new element, atomic number 94. But McMillan and Abelson were called away to do research on the atomic bomb. They suggested to a colleague, Glenn Seaborg (1912-1999), that he continue their research on neptunium. 

Each fission of uranium-235 releases additional neutrons. If one fission reaction produces two neutrons, these two neutrons can cause two additional fissions. If those two fissions release four neutrons, those four neutrons could then produce four more fissions, and so on, as shown in Figure 25-17. This self-sustaining process in which one reaction initiates the next is called a chain reaction. As you can imagine, the number of fissions and the amount of energy released can increase extremely rapidly. The explosion from an atomic bomb is an example of an uncontrolled chain reaction. 

---