> I get it, coolant system isn't functioning properly. Gotta vent steam. Just curious > why they aren't able to (or have decided to) scram it. Now they have a bigger issue.
Trouble is, it's a first-gen BWR - it was designed before the term SCRAM was coined. They've fully inserted all control rods (as you would in a SCRAM). This happened automatically when the vibration sensors were tripped. It can't generate any electrical power in this state, but the core still generates considerable heat. It needs external power to continue cooling the core. There are on-site diesel generators to supply this, but the earthquake damaged them. I think the USAF lent them some choppers to airlift in generators from elsewhere. Other aspects of the first-gen BWR design are also becoming problematic: low primary coolant capacity, hydrogen-generating reactions with control rods, and lack of secondary containment. Kind of sucks to be early adopters with this stuff.