Accident Avoided at Japanese Uranium Plant
of Japanese engineers successfully halted a fission chain-reaction inside
a uranium processing plant on Friday, a sign that Japan's worst nuclear
disaster was on the verge of coming to an end.
of residents were still being warned to remain inside their homes for
the remainder of the day, to avoid any possibility of exposure to harmful
radiation in the environment. Dozens, mostly workers from the plant, were
treated for contamination.
before dawn, engineers ordered workers to drain coolant water from a highly
radioactive tank at the JCO Co. plant in Tokaimura, approximately 120
km.(70 miles) northeast of Tokyo. The water magnifies a nuclear reaction
when it comes in contact with uranium. Engineers hoped that removing the
water would slow down or even suffocate the reaction.
containment levels immediately fell to a quarter of what they were before
the draining of the coolant water and were soon at a level officails said
were near normal.
Sato, chairman of the Nuclear Power Safety Committee, announced that the
reaction had ended at abot 9:30 a.m. Friday (0030 GMT). "For now,
the nuclear chain reaction has ended," he claimed in an interview
with reporters. "This is a very important first step in the process
of clearing up this accident."
fission reaction started when a worker skipped an integral step and mixed
too much uranium with nitric acid in a storage tank on Thursday, JCO Co.
officials stated Friday. They also stated that 16 kilograms (35 pounds)
instead of 2.4 kilograms (5 pounds), were used.
fission occurs when neutrons collide with uranium, causing atoms to split
and release huge amounts of energy and is the principle behind the atomic
bomb. Water stimulates the neutrons, spurring along the reaction.
to rescue workers, 55 people were suffering from radiation exposure, including
two workers who were in critical condition. Three paramedics who treated
the workers were hospitalized after they were contaminated.
officials stated that Thursday's accident released a gas containing alpha,
beta, and gamma radiation into the atmosphere. Levels of radiation reached
10,000 times the normal level shortly after the accident, officials said.
Resident within a 10-kilometer (6-mile) radius of the plant were told
to remain in their homes with windows and vents closed again on Friday.
Schools and transportation services were in the region were also halted,
affecting more than 300,000 people. Approximately 150 people were evacuated
from the plant's immediate vicinity.
governor of the local Ibaraki Prefecture, Masaru Hashimoto, said Friday
that authorities were considering enlarging the evacuation area from a
350-meter radius around the plant to a 500-meter radius.