Shaped charges are used to penetrate Russian tank hulls in Ukraine, and work by using explosives shaped in a very specific way to invert a copper cone and turn

Shaped charges are used to penetrate Russian tank hulls in Ukraine, and work by using explosives shaped in a very specific way to invert a copper cone and turn it into a hypersonic jet of hot goo. A nuclear device is an spherical array of them, all focused inward. If any of them goes first, it pushes things out of the way, and you get a "fizzle" You also have to shower things with a neutron pulse at just the right time to kick off the chain reaction.... while all the inbound hypersonic jets of goo are in flight. I'm amazed they were ever able to pull it off, let alone make them reliable.