[ RadSafe ] Fukushima contamination is 'chronic' - World News | IOL News | IOL.co.za

[Roger Helbig]

Please, take a look at the comment by frequent poster David Ludlow and
feel free to correct it.   Thanks

Roger Helbig

http://www.iol.co.za/news/world/fukushima-contamination-is-chronic-1.1244964


Fukushima contamination is ‘chronic’

February 29 2012 at 01:07am
By Laurent Banguet

Paris - Radioactive contamination levels from Japan's crippled
Fukushima nuclear plant have fallen sharply since the accident but
will be “chronic and lasting” for many years, a French watchdog said
on Tuesday.

“The initial contamination linked to the accident has greatly
declined,” Didier Champion, crisis manager at the Institute for
Radiological Protection and Nuclear Safety (IRSN), told reporters
almost a year after the disaster.

“That doesn't mean that there won't be any more, far from it. Today,
and for many years to come, we will have a situation of chronic and
lasting contamination of the environment.”

It was essential for Japan to maintain vigilant monitoring of fruit,
milk, mushrooms, game and fish, Champion said.

“There are risks of chronic exposure at low dosage, and without care
this can build up over time,” he warned.

The March 11 catastrophe saw the plant swamped by a quake-generated
tsunami that knocked out coolant pumps, triggered hydrogen explosions
and caused three of its six reactors to suffer meltdowns of nuclear
fuel.

Radioactive elements were spewed into the air by the blast and into
the sea by cooling water that was pumped in as part of a desperate
attempt to keep the overheated reactors under control.

The IRSN said the main radioactivity leaks occurred between March
12-25 in about 15 incidents, “of which the biggest probably took place
before March 15”.

It gave a provisional estimate that 408 peta-becquerels, or 408
million billion becquerels, of radioactive iodine had been emitted
into the air.

This was 10 times lower than in the 1986 Chernobyl disaster in
Ukraine, the world's worst nuclear accident.

The iodine releases posed a sharp but temporary hazard as the element
quickly decays. A bigger problem, the IRSN said, was caesium-137, a
long-lasting element which takes around 30 years to decay to half its
level of radioactivity.

Caesium of all kinds released at Fukushima was estimated by the agency
at 58 peta-becquerels, or three times less than Chernobyl. Caesium 137
accounted for 21 peta-becquerels.

Of around 24 000 square kilometres of land contaminated by caesium
137, only 600 square kilometres breached a safety threshold of 600 000
becquerels per square metre, the IRSN said.

This, again, was only a fraction of the territory contaminated by
caesium after Chernobyl.

However, there remained “hot spots” of contamination, up to 250km
away, where radioactive particles had been deposited by the weather.

So far, no death or cases of sickness have been directly linked to the
disaster, IRSN said, stressing however that the impact on the civilian
population over the long term, and on emergency workers and plant
employees, remained unclear. - Sapa-AFP