I would like to set up a perimeter for the map, so that the player does not wander off from a smaller area that is custom built. That area is not covering the entire map and is not square. KingGen seems to generate all maps as islands with water around them instead of radiation zones, which does not fit for the map I have in mind.
I was not aware that there were different types or levels of radiation. I would like to know more about this, but we might be getting off topic from the KingGen world generator.