Rabbit Holes

From inverse femtobarns, to the exploding bridge wire detonator, to the Power10 architecture. It’s really been a ride this evening.

Somehow I started to talk about Project Plowshare, the public works project with atomic bombs, with my co-worker tonight. For some reason I’ve always had a (unhealthy?) fascination with how nuclear devices work.

One of the components that you need to detonate an atomic bomb, an implosion device anyway, is to have an incredibly symetric compression of the core of your device. To do that you need to set off some conventional explosives around your pit. The thing is, you can’t just randomly blow things up. You need to be able to get a spherical shock wave to impinge on your core.

Working backwards, you need to have a really solid “tamper.” Usually this is made from depleted uranium, but there are some other options. You need to have an explosion outside of that that’s all simultanious. To get that, you use some novel explosive lenses that are made from different detonation speed explosives. That leads back to the source of the explosion. In the past that was done by the exploding wire detonators.

All they are is a wire that you… well… explode with hundreds of amps of current. That sets off the secondary explosive, which sets off the lenses, compressing the tamper, then boom!

So barns?

The cross-sectional area of the nuclei they were dealing with typically. I’m guessing the U-235 and Pu-239 variants.

This led to the slapper detonator, which was developed by the Lawrence Livermore National Lab.

Which is where the Sierra supercomputer lives.

That’s powered by the POWER9 CPU.

That brings us to 10.