It's because safety wasn't the obstacle to nuclear energy, cost was.
Also, I don't think passive safety of CANDU is what's meant by passive safety of HTGRs. The latter can survive losing cooling and everyone just walking away (in theory); I suspect the CANDU melts down in that situation, even if the chain reaction does stop.
Also, I don't think passive safety of CANDU is what's meant by passive safety of HTGRs. The latter can survive losing cooling and everyone just walking away (in theory); I suspect the CANDU melts down in that situation, even if the chain reaction does stop.