Yeah, I wondered about seacraft reactors myself. I think there are many safety allowances for DOD vs. DOE. The DOD reactors are not publicly accessible (you hope anyway), and the data centers will be in and near the public. There are also major security measures that have to be taken for reactor sites. You have armed personnel before you even get to the reactors, and then the entrances are sometimes close to one mile away from the reactor. Once there, the number of guards and bang-bags goes up. The modern sites kind of look like they have small henges around them (back to the neolithic!) :)