Not atomic, but important.

Those of us who spent any time at all in or around the US Navy Nuclear Power Program are quite familiar with the concept that any or every piece of important equipment must have more than one source of supply in order that supply be guaranteed and that problems be minimized with one or another design and that competition exists and so on and so forth. In fact, often you'll find a given piece of equipment replaced with another that works differently, looks a little different but fits the same mounting, has identical connections, and is a "substitute" and not a "twin," per se. We all know this.

Now, if we look at this site, we'll see that the engine program for the next generation all-services fighter aircraft is, very surprisingly, NOT of this character. This site and topic need a lot more press.