Yes, I forgot about CANDU. To fully describe the insanity of the Chernobyl design, we could add no secondary containment, graphite moderator but water coolant, poorly designed shutdown system, bad control rod design, and probably others I've forgotten. CANDU does not share any of those other insane features.
you may want to speak to the Canadians, as their reactor design also has a positive void coefficient
(admittedly a small one)