Detonating a nuclear weapon inside of a power plant isn't really practical. :-) Existing nuclear power plants don't get anywhere near the temperature and pressure needed to start nuclear fusion.
So, now we have the engineers trying all sorts of ways to get to the needed temperature and pressure without turning the plant into a smoking crater. That's where all the fancy lasers and magnetic pulses described in the article come in: They're trying to aim the heat source so they can superheat the fuel without melting the containment vessel.