First question I have about it: wouldn't it be an attractive target for bombing/terrorist attacks or would it be rock solid enough to withstand those?
The incidence rate of people inclined to terrorism is vanishingly low. And when you start talking about plots that require numerous people to cooperate, rather than a single lonewolf nut, there is even less to worry about. The more people a plot requires, the less likely it is to actually happen. Coordinated attacks against nuclear power plants or waste disposal facilities are fantasy.
There's some temporal sampling bias, here.
The threat of terrorism was huge and salient in 2002, and a lot of NRC regulations were updated at that time. It was less obvious in 2010. Here in 2021 it's hardly a threat at all. If we see another 9/11-scale attack this decade you can bet that will change.