Abstract
A number of controllable and uncontrollable factors can act to thwart efforts to make nuclear weapons or to secure fissile material. This chapter analyses three of the most serious of these. First, the reactors used to synthesize plutonium during the Manhattan Project used graphite as a moderating agent to slow neutrons. However, if the graphite is contaminated with even a small fraction of a neutron-absorbing element such as boron, the presence of such a contaminant can effectively poison the operation of the reactor. This chapter examines how much contaminant is tolerable. Second, within a bomb core itself, the fissile material will inevitably suffer some level of spontaneous fissions, which, if too great, can cause a predetonation. This problem led to the immensely difficult engineering challenge of implosion during the Manhattan Project. This chapter presents a detailed analysis of the spontaneous fission issue and how one can estimate the probability that a bomb will function correctly in the face of this problem. Finally, the presence of even a small amount of light-element contaminants within the core can lead to predetonation via what are called “α-n” reactions; this possibility sets stringent limits on the purity of the core material. Estimates of the tolerable levels of light-element impurities are developed.
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© 2011 Springer-Verlag Berlin Heidelberg
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Reed, B.C. (2011). Complicating Factors. In: The Physics of the Manhattan Project. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-14709-8_4
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DOI: https://doi.org/10.1007/978-3-642-14709-8_4
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