Bunkers being fixed locations means they could be targeted for attack. If it serves military purposes, there is a good chance it'll be targeted. If the sole pur

Bunkers being fixed locations means they could be targeted for attack. If it serves military purposes, there is a good chance it'll be targeted. If the sole purpose is as an embryo bank, it'd be useless if there is no trained staff to use it after the disaster, and keeping people there 24/7 would be unreasonable if it doesn't serve other purposes. A submarine has a much higher chance of survival, and is already being manned 24/7 for deterrence purposes.