Yes security is a key challenge. And not only do the reactors need security. Also the nuclear waste needs to be carefully protected. Any form of explosive plus

Yes security is a key challenge. And not only do the reactors need security. Also the nuclear waste needs to be carefully protected. Any form of explosive plus even a tiny amount of radioactive waste is basically a dirty bomb waiting to happen. So, there is simply no way that you could feasibly deploy small reactors anywhere else than basically highly secure places. Likewise for the storage. Likewise for transport of waste and reactors. That's one of the things that makes nuclear expensive. A thousand years of security cost for a few decades of not particularly cheap energy (before you consider centuries/milennia of storing the waste). Or 30000 if unlike this person seems to want we might not opt to build some more expensive nuclear plants to consume the waste of other ones that are already costing us too much per GWH.