Fears meltdown has begun as radiation spreads

[Guest guest]

http://www.abc.net.au/news/stories/2011/03/31/3178263.htm

Fears meltdown has begun as radiation spreads

Updated 1 hour 27 minutes ago

As dangerously high levels of radiation spread beyond the Fukushima exclusion

zone in Japan, there are fears the race to contain the nuclear crisis has been

lost and meltdown has already taken place.

Radiation measured at a village 40 kilometres from the Fukushima nuclear plant

now exceeds a criterion for evacuation, the UN nuclear watchdog said.

And a Japanese nuclear expert has warned crews may have to keep pouring cooling

water onto the stricken reactors for years.

The radiation finding increases pressure on Japan's government to extend the

exclusion zone beyond 20 kilometres around the plant, which was hit by a huge

earthquake and tsunami on March 11, knocking out the cooling system of the

plant's six reactors and setting off explosions and fires.

Prime minister Naoto Kan says he is considering enlarging the evacuation area to

force 130,000 people to move in addition to the 70,000 already displaced.

The indications are the most serious nuclear crisis in 25 years is getting

worse.

Lahey, head of safety research for this type of reactor at General

Electric, which installed the reactors at Fukushima in the 1970s, says workers

at the site appear to have lost the race to save the crippled No. 2 reactor.

The Guardian newspaper quotes him as saying he believes the reactor core has

melted through the bottom of the pressure vessel and at least some of it is down

on the concrete floor beneath.

This would mean in simple terms the accident is no longer a matter of melting

fuel rods, but of meltdown.

That situation is reminiscent of Chernobyl where the plant needed to be covered

with a concrete sarcophagus to seal it off.

However Dr Lahey says there is no danger of a Chernobyl-style catastrophe

because in that case the plant exploded releasing a massive amount of

radioactive steam.

The situation in Japan would still be immense environmental damage in the

localised area.

Hiroto Sakashita, a nuclear reactor thermal hydraulics professor at Hokkaido

University, says the other reactors and cooling ponds will take years to cool.

" They will just have to keep on pouring and pouring but contaminated water will

keep leaking out, " he told The New York Times.

Japan's Nuclear Safety Agency has confirmed radioactive iodine in the sea near

Fukushima at 3,355 times the normal level.

Workers at the nuclear plant are planning to spray the grounds with a special

resin designed to block radioactive materials from spreading into the soil, the

sea and into the air.

Officials at the stricken plant are also planning to cover three badly damaged

outer reactor buildings with special fabric caps and fit air filters to limit

the release of radiation.

Another plan is to anchor an empty tanker off the No. 2 reactor so workers can

pump huge volumes of radioactive water into its hull.

Japan, which has more than 50 reactors, has ordered an immediate check of them

all to ensure there can be no repeat of the Fukushima crisis.

Industry minister Banri Kaieda has written to the CEOs of every nuclear power

operator demanding they carry out drills to prepare staff for emergencies and

urging them to ensure their plants have reliable back-up power for their cooling

systems.

Meanwhile, IAEA head of nuclear safety and security Denis Flory says he has

heard there might be " recriticality " at the Fukushima plant, in which a nuclear

chain reaction would resume, even though the reactors were automatically shut

down at the time of the quake.

He says this could lead to more radiation releases but it would not be " the end

of the world " .

" Recriticality does not mean that the reactor is going to blow up, " he said.

" It may be something really local. We might not even see it if it happens. "

- ABC/Reuters