CANDUs have some problems. They're big, they're expensive, they have reliability problems, they're slow, and they have a positive void coefficient (which scares

CANDUs have some problems. They're big, they're expensive, they have reliability problems, they're slow, and they have a positive void coefficient (which scares people off more than being an extreme safety issue). Overall, burning the very finite U235 supply at 50% or so better efficiency is worth it if you're going to have a nuclear program, but they don't achieve the primary/only goal of most civilian nuclear programs which is to subsidize infrastructure for a weapons program with public money and make it more palateable. As such noone really adopts them.