CHAPTER NINETEENFig. 77: 1945 Gun-Type Nuclear Device (“Little Boy”) Source: Credit: Howard Morland (Wikimedia GNU free documentation license version 1.2)Fig. 78: Plutonium Ratios in Used Fuel Source: https://beyondnerva.com/radioisotope-power-sources/%20radioisotope-selection-for-rhu-fuels/americium-241/Fig. 79: Fuel Pellet “Bambooing” Source: https://www.researchgate.net/figure/Illustration-of-fuel-swelling-and-clad-deformation-due-to-PCI-a-Fresh-fuel-before_fig7_342124328