If I recall correctly, the scientist in question was actually the head of an independent East German effort to design and construct a nuclear weapon which the Soviets shut down after the found out (understandably so). As the head of the program and obsessed with nuclear weapon technology, it is not surprising that he had a good grasp on all of the general areas of the design of a nuclear weapon, which in concept is not that complex. However, I would have to agree that it is unlikely that a single scientist or engineer would possess sufficient expertise in all of the required areas to perform the detail engineering by himself, and it would certainly take longer than just the few months in the timeline of the book even with the assistance of another engineer and some technicians to develop all of the engineering documentation and processes to construct a weapon. There is far more to any complex engineered device than just mechanical drawings (i.e. ‘blueprints’, which by the way is a term no one in engineering practice uses as the nasty-smelling blueprint machines and smearing blueline copies have essentially disappeared as soon as CAD data storage became practical) that are necessary to build and test a complex engineered system.
It is not infeasible, however, that an experienced weapon designer could train engineers in the various areas to be able to develop a portable-sized weapon as described given the basic nuclear materials available from a discarded weapon. The basic simulation techniques and machining equipment that was once highly specialized is now available at commodity prices and useable by anyone with basic engineering and mathematical computing knowledge, and the components necessary for critical timing are found in photocopiers and specialty high speed photography equipment. Given a group of bright and motivated high school students you could probably train and direct them to build a weapon inside of a year. It’s not easy in the sense that building IEDs is “easy”, but all of the basic technologies, other than producing fissile material, are readily available to anyone sufficiently determined to apply them.
I don’t think the Soviets had CAD systems in common use even near the end of the 80s and the fall. I’d love to be corrected on that, but I read articles talking about them having to steal microprocessors, and early personal computers - 1988 era - didn’t have much RAM or disk space or high monitor resolution.
This brings up a personal story. Many years ago while looking for something at our lab’s library (NASA), I spotted the DuPont Blasters Handbook. Looked like fun reading so I checked it out. This was back when we still used library cards and I could see I was the first person to check it out in like 20 years. Many years later I went to look through it and discovered it had been removed from the catalog. Not surprising in itself given the increasing trend for security. But then I thought, I’m like the only person to have read this damn thing, I’m not just on some watch list, I am the list!
But here is what I was trying to refresh my memory about. There was a frontispiece about the largest man-made explosion. It was the clearing of some underwater obstruction like a small mountain in the harbor of a northwestern state. Puget Sound comes to mind. It detailed how they tunneled into the mountain and stacked the boxes of TNT, and how high the water spray went.
But I cannot find any mention of this act. Has anyone heard of it? I just looked for the handbook and found a copy to download, but it does not have that cover story.