Japan Says Fuel May Have Melted Through
Staff - Tuesday Jun. 7, 2011
admitted Tuesday that damage to the reactors at the
Fukushima nuclear plant was worse than previously thought,
as it conceded it was unprepared for the severity of the
In a report
being submitted to the International Atomic Energy Agency,
the UN's nuclear agency, the Japanese government said the
nuclear fuel in three reactors likely melted through the
inner containment vessels, not just the core. It said fuel
may have burned through the reactor pressure vessels of
Units 1, 2 and 3 and into their outer steel containment
report also acknowledges design flaws in its reactors. Among
the flaws was the location of spent fuel cooling pools high
in the buildings. That resulted in leaks of radioactive
water into lower levels, which hampered repair work.
As well, the venting system for the containment vessels
lacked filtering capability. Attempts by plant workers to
vent pressure to prevent the overheating containment vessels
from bursting repeatedly failed.
said the delay in venting was a primary cause of explosions
that further damaged the reactors and spewed huge amounts of
radiation into the air.
The report also acknowledges the need for greater
independence for the country's nuclear regulators.
"In light of
the lessons learned from the accident, Japan has recognized
that a fundamental revision of its nuclear safety
preparedness and response is inevitable," the report said.
apologized to the international community in the report,
expressing its "remorse that this accident has raised
concerns around the world about the safety of nuclear power
was released a day after Japan more than doubled its earlier
estimate of total radiation that was released into the air
in the first days of the disaster.
The country's Nuclear and Industrial Safety Agency (NISA)
now says it believes 770,000 terabecquerels escaped into the
atmosphere in the first six days – a figure much higher than
its earlier estimate of 370,000 terabecquerels.
The new estimate is closer to that of Japan's independent
Nuclear Safety Commission, which had initially estimated a
release at 630,000 terabecquerels in the first month.
Although the amount is just 15 per cent of the total
radiation released in the Chernobyl disaster in 1986, it
suggests the contamination of the area around the plant is
worse than first thought.
plant at Fukushima is still leaking radioactive material,
nearly three months after an earthquake and tsunami knocked
out the plant's cooling systems. But the government says it
is still on track to bring the reactors to a cold shutdown
More than 80,000 local residents living within a 20km radius
of the plant were evacuated after the March disaster and
still haven't returned to their homes.