As heroic workers and soldiers strive to save stricken Japan
from a new horror—radioactive fallout—some truths known for 40
years bear repeating. An earthquake-and-tsunami zone crowded
with 127 million people is an unwise place for 54 reactors. The
1960s design of five Fukushima-I reactors has the smallest
safety margin and probably can't contain 90 percent of
meltdowns. The U.S. has six identical and 17 very similar
plants. Every currently operating light-water reactor, if
deprived of power and cooling water, can melt down. Fukushima
had eight-hour battery reserves, but fuel has melted in three
reactors. Most U.S. reactors get in trouble after four hours.
Some have had shorter blackouts. Much longer ones could happen.
Overheated fuel risks hydrogen or steam explosions that damage
equipment and contaminate the whole site--so clustering many
reactors together (to save money) can make failure at one
reactor cascade to the rest. Nuclear power is uniquely
unforgiving: as Swedish Nobel physicist Hannes Alfvén said