These blackouts are expected to continue for several weeks, agency boss Tetsuhiro Hosono said.

BBC: Japan quake: Nuclear closures to cause power shortages

Government spokesman Goshi Hosono said the latest setback would not affect the deadline.

BBC: Japan nuclear: Tepco halts Fukushima cooling plan

That won't work in Japan, where land is scarce and attachments to it are strong, says Mr. Hosono, the nuclear-crisis minister.

WSJ: Japan to Take 40 Years to Dismantle Fukushima Nuclear Plant