Posts
Rise
in wildfires may resurrect Chernobyl’s radiation
9
February, 2015
Fallout
from the world’s worst nuclear accident just won’t go away.
Radioactive clouds may once again spread over Europe, as rising fires
release radiation locked up in the upper layers of soil in the dense
forests near Chernobyl in Ukraine and Belarus
Forest
fires there have already been re-distributing that radioactivity over
Europe. But the situation is set to worsen with climate change,
political instability – and a bizarre effect of radiation on dead
leaves.
After
a reactor at the Chernobyl nuclear plant exploded
in 1986,
people were evacuated from 4800 square kilometres of the most heavily
contaminated areas in Ukraine and neighbouring Belarus. This
“exclusion zone” became a haven
for wildlife and
a dense boreal forest.
Nikolaos
Evangeliou at
the Norwegian
Institute for Air Research and
colleagues have analysed the impact of forest fires in the region,
and calculated their future frequency and intensity. To do so they
fed satellite images of real fires in 2002, 2008 and 2010, and
measurements of radioactive caesium-137 deposited on the area, to
models of air movements and fires.
They
estimate that of the 85 petabecquerels of radioactive caesium
released by the Chernobyl accident, between 2 and 8 PBq still lurk in
the upper layer of soil in the exclusion zone. In another ecosystem
this might gradually fall with erosion or the removal of vegetation.
But in these abandoned forests, says Evangeliou, “trees pick up the
radioactive ions, then dead leaves return it to the soil”.
Radioactive smoke
The
team calculates that the three fires released from 2 to 8 per cent of
the caesium, some 0.5 PBq, in smoke. This was distributed over
eastern Europe, and detected as far south as Turkey and as far west
as Italy and Scandinavia.
“The
simulation probably underestimates the potential risks,” says Ian
Fairlie,
former head of the UK government’s radiation risk committee, who
has studied the health
impacts of Chernobyl.
That’s because the estimate depends on the half-life the team
assumed for Cs-137, he says, and some investigators believe it is
longer.
The
team’s calculated release would have given people in the nearby
Ukrainian capital, Kiev, an average dose of 10 microsieverts of
radiation – 1 per cent of the permitted yearly dose. “This is
very small,” says Tim
Mousseau of
the University of South Carolina at Columbia, a co-author of the
study. “But these fires serve as a warning of where these
contaminants can go. Should there be a larger fire, quite a bit more
could end up on populated areas.”
And
the average dose isn’t the problem. Some people will get much more,
as fires dump radioactive strontium, plutonium and americium as well
as caesium unevenly, and as some foods concentrate these heavy
metals, for example caesium in mushrooms. “The internal dose from
ingestion can be significant,” says Mousseau. The resulting cancers
might be hard to spot among many other less-exposed people. “But
they will be very significant for those who experience them.”
Increased
forest fires seem likely. The area is due to get drier, according to
the Intergovernmental Panel on Climate Change. The team found
that droughts
are already worsening forest fires in
both area and intensity, and those are predicted to worsen.
This
may be down to a range of factors, including lack of management of
the forests. Most forests are managed by removing dead trees,
clearing roads or cutting fire breaks but this isn’t being done
here. Moreover, dead vegetation that fuels fires is accumulating at a
rate that has doubled since 1986, the team says.
Insect killer?
This
is partly because the radiation itself seems to inhibit the decay of
leaf litter, perhaps because it kills key insects or microorganisms.
“We brought litter from an uncontaminated zone into a contaminated
area and found it decayed only half as fast,” says Evangeliou.
The
models predict peaks of forest fires between 2023 and 2036. By 2060,
fires might continue, but much of the radioactive fallout will have
decayed away.
To
cap it all, once a fire starts, local fire-fighters in Ukraine have
seven times fewer crews and equipment per 1000 hectares than
elsewhere in the country – a situation unlikely to improve given
the ongoing conflict. The UN Environment Programme is installing
video surveillance for fires, but much of the forest is inaccessible
or slow to reach due to blocked roads. “It’s like a jungle in
there,” says Evangeliou.
“This
is clearly an important problem and one that applies also to
Fukushima, where a significant amount of forest land has been
contaminated,” says Keith
Baverstock of
the University of Eastern Finland in Kuopio, formerly head of
radiation protection at the World Health Organization’s European
office. “They have a very valid point. The lack of management of
forests, the apparently slower decay of vegetation exposed to
radiation, climate change leading to drought and the expansion of
forested areas all contribute to increasing the risk of forest fire
and therefore further dispersal of long-lived radioactive nuclides.”
The
actual amount of radioactivity redistributed by the recent fires is
about a tenth of what was deposited on Europe in 1986, and its health
effects are still a matter of debate among epidemiologists. But
long-lived emitters of radioactivity persist and accumulate, so any
dose is bad news, says Mousseau. “A growing body of information
supports the idea that there is no threshold below which they have no
effect.”
Journal
reference: Ecological
Monographs, DOI: 10.1890/14-1227.1
Fukushima a “ticking time bomb”
- Fires
now “raging” near nuclear plant
- Blaze
doubles in size; “Smoke rising from wide areas”
- Concern
over fallout of highly radioactive material; Officials closely
watching radiation levels (VIDEO)
1
May, 2017
NHK
World,
May 1, 2017 (emphasis added): Wildfire
continues in Fukushima —
A wildfire has been raging
for more than 2 days near the damaged Fukushima Daiichi nuclear power
plant…
The area is part of a zone designated as “no-entry” due to high
radiation levels…
Fukushima and Miyagi prefectures and the Self-Defense Forces are
using helicopters to fight the blaze. They are also looking
at the possibility of using ground crews.
Footage from an NHK helicopter on Monday morning showed smoke
rising from wide areas and fires burning in several locations…
Mainichi,
May 1, 2017: Wildfire
rages in highly radioactive Fukushima mountain
forest —
A fire broke out in a mountain forest near the crippled Fukushima No.
1 Nuclear Power Plant on the evening of April 29, consuming an area
approximately 20 hectares in size, according to prefectural
authorities… As the fire
continued to spread,
however, helicopters from the GSDF, Fukushima Prefecture and other
parties on May 1 resumed fire extinguishing operations from around 5
a.m. … As of May 1, there were no majorchanges
to radiation levels in
the heart of Namie and other areas near the fire scene, according to
the Ministry of the Environment. “We
will continue to closely watch changes in radiation doses in
the surrounding areas,” said a ministry official.
Common
Dreams,
May 1, 2017: Sparking
Fears of Airborne Radiation, Wildfire Burns in Fukushima ‘No-Go
Zone’; Contaminated forests such as those outside fallout sites
like Fukushima and Chernobyl ‘are ticking time bombs’ —
A wildfire broke out in the highly radioactive “no-go zone” near
the crippled Fukushima nuclear power plant over the weekend,
reviving concerns
over potential airborne radiation…
Local officials were forced to call in the Japanese military… In a
blog post last year, Anton Beneslavsky, a member of Greenpeace
Russia’s firefighting group who has been deployed to fight blazes
in nuclear Chernobyl, outlined the specific dangers of wildfires in
contaminated areas. “During a fire, radionuclides like caesium-137,
strontium-90 and plutonium rise into the air and travel with the
wind,” Beneslavsky wrote. “This is a health concern because when
these unstable atoms are inhaled, people become internally exposed to
radiation.” Contaminated forests such as those outside fallout
sites like Fukushima and Chernobyl “are ticking time
bombs,” scientist
and former regional government official Ludmila Komogortseva told
Beneslavsky. “Woods and peat accumulate radiation,” she explained
“and every moment, every grass burning, every dropped cigarette or
camp fire can spark
a new disaster.”
Sputnik
News,
May 1, 2017: Japanese
Authorities Fighting Wildfire in Evacuation Zone Near Fukushima NPP…
There were no
reports either about the wind direction or the changes in the
background radiation level in
relation to the fire.
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