Ah, but this reactor's coolant is not sodium, but lead. Much more inert.
"Case in point is the pebble-bed reactor; it’s less dependent upon cooling loops and contains the fissile material in such a manner so as to minimize the chance for runaway reactions."
The PBR has not lived up to its hype. It turns out that examination of test reactors has revealed unexpected major instability in the fuel elements (pebbles). There was serious discussion of this problem on an earlier post some months back.
True that. I prefer Coors. But hey - it's pretty impressive that PBR can be used to generate nuclear power! Who knew?