i tried to start watching it but stopped

and yeah, the immediate toxicity is primarily from iodine 131, and to a lesser extent from caesium 137 but both of those are all decayed to much less toxic things within weeks

that is not to say that the fine dusty uranium that boils out and recondenses and blows around is not toxic, just that its effects are slow, it doesn't absorb easily except into the lungs and doesn't pass from there easily into the blood, but the cancer rates are way above what they would have been since 1986 for decades afterwards

but yeah, plutonium reaction is not a meltdown, it's so hot it explodes with more force than any chemical, hydrogen/oxygen/nitrogen based explosives, and mostly the atoms are shattered into subatomic high energy particles and electrons, so there is not a lot of this splitting into other elements like the iodine and cesium