A surprising application

A recent discussion involved the point that modern physics is very far removed from real-world applications. Here's an example of a possible application of some physics that I would not have anticipated (despite knowing enough to do so).

A novel way of spying on rogue nuclear activity

Interesting. I'm kind of surprised though. I thought we already had technology that worked as well as that. I thought we could detect such things with current technologies. 

I understand the usual way is with photographs. Surely only light and neutrinos go far enough for remote detection?