Critical Mass and Efficiency

  • B. Cameron ReedEmail author


This chapter forms the heart of this book. After deriving the properties of neutron travel through materials, a detailed analysis is presented of how the critical mass of a fissile material, in both “bare” and “tampered” configurations, can be calculated. The calculations are applied to both uranium-235 and plutonium-239. Analytic expressions are developed for estimating bomb energy yield and efficiency. A numerical simulation is developed to analyze conditions of pressure, fission rate, expansion, and energy yield within a fissioning bomb core, and is applied to the Hiroshima Little Boy bomb. Spreadsheets for performing the calculations are made available to interested users through a supporting website.


Outer Radius Nuclear Weapon Critical Mass Critical Radius Spontaneous Fission 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Department of PhysicsAlma CollegeAlmaUSA

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