MTBF analysis has yielded to prospective validation, which has become so good in some industries as to virtually preclude such events. Think "zero defects" programs such as at Toyota.
As for the security issue, you are dreaming if you think the NRC will allow any kind of nuclear plant to run without guards, razor wire fences, dogs, microwave intrusion alarms, CCTV cameras, etc.
Razor wire: sure.
Fences: absolutely.
Dogs: maybe, daily visit.
Microwave intrusion alarms: of course.
CCTV cameras, obviously.
Guards: on call.
How about a robotic defense capability?
It's all doable for less than the price of the staff.
I really don't think it impossible. Remember: it's small; it's encased in steel and concrete; there is no fuel or waste storage; there is nothing to be sabotaged without first breaching containment. As for the NRC, well, who the hell knows?
In this day and age we all know that would incite crowd to protest. I even remember a design for a nuclear watch battery clear back from the 60s.
Now if it even has the word "nuclear" in it, people seem to panic. For example, NMRs were renamed MRIs to alleviate patient fear of the word "nuclear".