FUKUSHIMA, Japan — Military fire trucks have been spraying the reactor units at a damaged Japanese nuclear plant for a second day.

Tons of water has been sprayed over the facility, as part of
the effort to keep reactor fuel from overheating and sending out
dangerous levels of radiation.
 

The head of the U.N.'s International Atomic Energy Agency, who's
visiting Japan, says crews are "racing against the clock."
 

The Japanese government is conceding it was unprepared for a
disaster of that scale and was slow to respond. The prime minister
is vowing to "rebuild Japan from scratch." He says the disasters
have brought a "great test for the Japanese people."

The government is now welcoming U.S. help as it tries to
stabilize its overheated, radiation-leaking nuclear complex. It's
also raised the severity classification for the nuclear crisis,
putting it on a par with the 1979 Three Mile Island accident.

Along the coastline today, sirens wailed to mark one week since
the disasters that triggered a nuclear emergency.