I severely doubt this is any safer from the meltdown problem than other designs.
Since the "primer source" is nothing but some highly radioactive material all that has to happen for a meltdown scenario is that the mechanism regulating the link between it and the reactor to lock up. It's exactly the same problem.
True although stopping active fission is relatively easy. The harder to solve problem is decay heat. Modern reactor designs employ passively safe measures which are designed to keep reactor cool (dissipate decay heat) without the need for pumps and/or electrical power.