[MertsA]

Sure, there was some details about the reactor design that were not disclosed because "state secrets" but the very glaring error occurred after the operator deliberately ignored the safety limits that were shared and knowingly exceeded that by withdrawing all of the control rods. I'm not saying the USSR didn't have any capable nuclear engineers, but that operator should never have even stepped foot in a control room with their lack of knowledge of nuclear physics and a blatant willingness to just push forward when they know they don't understand what the reactor was doing. Add on top of that management insisting that they push on and get the reactor up to power, to hell with the consequences. Xenon poisoning after high output operation was not some secret safeguarded knowledge. The reactor operating limits were known to the operator, he decided to blow past them anyways.

I'd call their behavior, both management and the operator, reckless and incompetent. Even in the original design to forego a full containment structure, that was predicated on making sure that the operating limits specified were never exceeded and no one bothered to check to see if the night shift guy was clueless or not. It'd be one thing if they followed up the design to forego the containment structure with rigorous controls around ensuring competent operators and hard physical limits on reactor operations but they didn't.