Although not on the scale with Chernobyl, the Windscale release of iodine-131,
caesium-137 and xenon-133 are thought to have caused at least 200 cancer cases;
Although maybe they should have thought twice before double-heating the core on the 8th, or increasing the airflow on the 10th,
the factors that really caused the Windscale fire were those of policy,
made at a pay grade far above their heads by people who didn't really typically have the engineers' expertise on the subject.