Huh. OP seems to feel concerned about one instance in over 200,000 successful tests. Most under water.
Here's a secret newb. Despite what is spilling into water and food table the situation @ Chernobyl is still worse long term. The ability of a runaway core to destabilize the subatomic nature of even lead (thermium IIRC) is somewhat mitigated by a crystallization process in water.
One day, millennia from now thecore@Chernobyl (meaning wild wormwood

) will breach the containment and hit the water table. Before that it will essentially destabilize all matter around it permanently. After... well at least by then our children's childrens' children's children's bastard mutants will all be dead.
HI NIGEL!! GLAD TO SEE YOU BROUGHT THE DICKS!!!