I don't think airliners use PRIST.
Bulk fuel freezing is not the problem...the bulk fuel is not allowed to get that cold ( -40 for normal jet A). Fuel recirculation and/or dumping heat from other systems keeps it well above that.
But on long, high-altitude flights fuel can get cold enough to freeze water. Like somebody mentioned, there is always some trace amount of water...unless the fuel is allowed to sit undisturbed for an extended period (days?) the water will not seperate out.
The real issue appears to be a combination of a very long, unusually cold flight, and some design feature of the 777 fuel system which can allow the build-up of suspended ice crystals at a flow-restriction point under certain circumstances.
It's also possible they got fuel with higher-than-normal water content which would have aggravated the siuation.
The 777 has been flying for well over a decade now...I suspect it would take a very precise combination of circumstances to repeat this incident.