This is an early designed (late 50’s design) plant, it doesn’t have a secondary containment dome. If they lose control and there is a steam explosion radiation will likely spread.
Fukushima I?
Supposedly it does.
Then there is this about reactor 1:
“Fukushima reactor pressure may have hit 2.1 times capacity -METI,” Maeda, Rita, Reuters wire service, quoting Japan Trade Ministry (20:30 GMT) 12 March 2011 (Tokyo time)
Reactor 2 is also experiencing cooling problems.
They are racing to get batteries there. The reactors will melt down without them.