Correct me if I'm wrong but isn't the idea of safe pool reactors that hydrogen-neutron heat transfer is more efficient than normal radioisotope-water heat transfer. If you shut down the pumps and heat increases, spectral hardening cools the reactor faster and disperses the energy into larger volume than convection using pumps.

Is that really true? My understanding is that ordinary boiling water reactors contain safety systems that work just by boiling. Reading the wikipedia article[1], the Isolation Condenser, the Automatic Depressurization System, and the Gravity-driven Cooling System all work just by water boiling and with natural convection in the water, without any active pumps, and they are supposedly enough to keep the core from melting.

[1] https://en.wikipedia.org/wiki/Boiling_water_reactor_safety_s...