> that's close to 1 neutron per second.

> They are getting 10 per second. They are nuclear engineers and I'm just a guy who knows how to multiply and how to read wikipedia. Most likely their number is correct.

Nicely done! It gets complicated, well beyond my current understanding. However, U238's first decay product is Thorium234, which has a half life of 24 days. Thorium234 in turn decays into Proactinium, which has a half life of 1.17 minutes. There are 16 more decays until finally arriving at Pb206 (lead), which is stable.

These decays must give room for lots more neutrons to emerge.