The confusing part about the article was that it initially stated that they were very small, and then went on to speak about billiard ball size. Does that mean that the protective coating is very thick, or that there’s a range of sizes for the actual uranium mass?

I remember reading in one of Feyman’s biographies about how he visited an early fuel plant, and was horrified to see them storing what amounted to a near a critical mass in barrels, in long rows. we’ve come some way since.