From the BBC:
“Ukraine
nuclear plant: How risky is stand-off over Zaporizhzhia?”
The rhetoric
surrounding Europe's biggest nuclear power plant - close to the front line in
Ukraine - is becoming increasingly alarming, with international figures warning
of the risk of a major accident. UN Secretary General António Guterres believes
potential damage to the Zaporizhzhia plant could be "suicide" and
Turkey's president has said no-one wants another Chernobyl - the world's worst
nuclear accident, when Ukraine was under Soviet rule. Russia seized the site on
the left bank of the River Dnieper at the start of its war but this month the
two sides have accused each other of repeatedly shelling it. Each claims the
other is planning a provocation. Ukraine says a Russian film crew has already
staged an attack to blame on Kyiv. Russian defence officials have produced a
map showing how a radioactive cloud might spread from the plant from Ukraine to
neighbouring countries, including Hungary, Poland and Slovakia.
What, then, is
the risk to this nuclear plant which houses six reactors - and is Europe facing
a Fukushima-type meltdown? "I wouldn't be too worried," says Mark
Wenman, head of the Centre for Doctoral Training in Nuclear Energy Futures. "Zaporizhzhia
was built in the 1980s, which is relatively modern. It has a solid containment
building. It's 1.75m [5.75ft] thick, of heavily reinforced concrete on a
seismic bed [to withstand earthquakes]... and it takes a hell of a lot to
breach that." He rejects comparisons with either Chernobyl in 1986 or
Fukushima in 2011. Chernobyl had serious design flaws, he explains, while at
Fukushima the diesel generators were flooded, which he believes would not
happen in Ukraine as the generators are inside the containment building. Much
of the anxiety has been about the plant coming under fire from artillery shells
or rockets. Ukraine has accused Russian forces of using it as a shield from
which to fire on nearby cities. Russia denies that is the case.
That may not
be the biggest risk. After 9/11, nuclear plants were tested for potential
attacks involving large airliners and found to be largely safe. A potentially
more serious hazard could come if the power supply to the nuclear reactors and
back-up generators was lost and led to a loss of coolant. With no electricity
to power the pumps around the hot reactor core, the fuel would start to melt. Lt
Gen Igor Kirillov, who heads Russia's nuclear protection corps, said the
plant's support systems had already been damaged by shelling, and that kind of
pump and generator failure could lead to the reactor core overheating and the
plant's facilities being destroyed. "That wouldn't be as serious as
Chernobyl, but it could still lead to a release of radioactivity and that
depends which way the wind's blowing," says Claire Corkhill, professor of
nuclear material degradation at the University of Sheffield. For her, the risk
of something going wrong is genuine - and Russia would be just as much at risk
as Central Europe.
The UN's
atomic energy authority, the IAEA, warns of a "very real risk of nuclear
disaster" and has asked to be allowed access to the site as soon as
possible. The UN secretary general has called on Russia to pull its troops out
and demilitarise the area with a "safe perimeter". Russia has
refused, arguing that would make the plant more vulnerable. Ukraine's nuclear
agency says three of the four power transmission lines linking the plant to
Ukraine have already been damaged by rocket fire. If the last source of power
is also broken, the agency believes nuclear fuel will begin melting
"resulting in a release of radioactive substances to the
environment", and diesel generators will not provide a long-term solution.
But Prof Iztok
Tiselj, chair of nuclear engineering at the University of Ljubljana in
Slovenia, believes the risk of a major radioactive incident is minimal as only
two of the six reactors are now operating. "From the standpoint of
European citizens there's no reason to worry," he says. The other four are
in a state of cold shutdown, so the amount of power needed to cool the reactors
is smaller. Mark Wenman is full of praise for the Ukrainian staff at the plant
who reduced the number of reactors in operation. That means that even though
the radioactive products continue to be radioactive, the so-called "decay
heat" after a shutdown decays exponentially with time. "Provided the
diesel generators are in good shape, even if they lost electricity from the
grid they should be able to cool the reactor," he says. Another major
safety fear could come from the spent fuel at Zaporizhzhia. Once the fuel is
finished the waste is cooled in spent fuel pools and then moved to dry cask
storage. "If these were to be damaged there would be a release of
radioactivity but it wouldn't be anywhere near as serious as the loss of
coolant," says Prof Corkhill. And Iztok Tiselj believes any release of
would be so small as to be negligible.
At the heart
of this crisis are the plant's original staff, working under Russian occupation
and quite probably under a great deal of stress. They have complained of the
plant coming under continuous attack but warn the real threat of disaster would
emerge if Russia shut the whole plant down, so it could disconnect the supply
from Ukraine and reconnect it instead to Russian-occupied Crimea. Dr Wenman
believes it is the human factor that represents the biggest risk of a nuclear
accident, whether because of chronic fatigue or stress: "And that violates
all the safety principles." If something were to go wrong, they would need
to be on top form, and one can imagine they are not, says Claire Corkhill.
The head of
the IAEA, Rafael Grossi, appealed for the staff to be left to carry out their
duties "without threats or pressure". A letter signed by dozens of
employees at the plant on Thursday called on the international community to
stop and think: "We can professionally control nuclear fission," it
said, "but we are helpless in the face of people's irresponsibility and
madness."
^ No Nuclear
Power Plant in Ukraine or anywhere in the World should be used as a Military
Base or attacked with Missiles, Bombs, etc. ^
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