The report doesn’t share your analysis. This is all conjecture.
You’d expect a spike in radiation if the containment were compromised, which hasn’t occurred.
Two, the core is subcritical now, which means that even if it were exposed, it wouldn’t be able to go critical as what happened in chernobyl.
Breaking: Dai-ichi Unit 2: Ability to cool unit has been lost. Fuel rods have been fully exposed, at least twice. An attempt to channel seawater into the reactor failed due to stuck rod.