Continuing the comic from the first image: Calculus: Restricted by the graphite that surrounds them, they continue through the pile, and end up by hitting one of the rare atoms of U.235. These in turn split and release two or three neutrons again...You see? Haddock: Of course! It's child's play... Calculus: But this process has to be controlled. Thanks to the cadmium rods which absorb a proportion of the neutrons, we can regulate the working of the pile as we wish.
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