Clean future in nuclear power
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Barry Brook and Martin Nicholson
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From:
The Australian
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December 04, 2009
12:00AM
WE may not be getting an emissions trading scheme any time soon but the
climate and energy crises still need fixing with real urgency.
For
climate, the issue is excess greenhouse gases from burning fossil
fuels. For energy, the crisis is dwindling supplies of those fuels and
air pollution from coal combustion.
Replacement energy sources
need to be reliable, plentiful and economic to deploy. They need to be
low-carbon to minimise global warming. Business-as-usual or half
measures risks saddling future generations with a climatically hostile
planet and energy scarcity.
Nuclear power is one obvious replacement source, but typically raises five objections.
First,
readily available uranium supplies are limited. If the world was wholly
powered by present-style nuclear reactors there would be at most a few
decades of energy before cheap uranium was exhausted.
Second, nuclear accidents have happened in the past, suggesting this technology is dangerous.
Third, expansion of nuclear power would risk the proliferation of nuclear weapons.
Fourth, we would leave future generations with the legacy of long-lived nuclear waste.
Fifth,
large amounts of energy (and possibly greenhouse gases) would be
required to mine, mill and enrich uranium and to build and later
decommission nuclear power stations.
All the above points have
merit, although their relative importance comparedwith climate change
and critical energy shortages is debatable. But there is little point
in debating these objections because none will apply to future nuclear
energy generation.
Almost all today's nuclear power stations are
thermal reactors. These use water to slow the neutrons that cause
uranium atoms to split (fission) and to carry the heat generated in
this reaction to a steam turbine to generate electricity.
Because
of the gradual build-up of fission products (neutron poisons) through
time, we end up getting less than 1 per cent of the useable energy out
of the uranium. The rest is thrown out as that long-lived waste.
In
contrast, newer fast reactors are able to use almost all of the energy
in uranium. There is enough energy in already mined uranium and stored
plutonium from existing stockpiles to supply all the world's power
needs for more than three centuries before we need to mine any more
uranium.
Fast reactors can be used to burn all existing reserves
of plutonium and the nuclear waste from the past and present generation
of thermal reactors. With additional uranium mining, there is enough
energy in proven deposits to supply the entire world for many thousands
of years. This deals with the first objection.
As to the second
objection, modern reactors use passive safety systems requiring no
operator intervention to shut down the reaction. This makes them safe.
So safe that a certification assessment for Westinghouse's AP-1000
reactor put the risk of a core meltdown such as the one that occurred
at in the US in 1979 at Three Mile Island at once every 24 million
reactor years.
Comparing the flawed Chernobyl design to today's
reactors is like saying modern aviation is too dangerous because the
Hindenburg airship exploded in 1937.
On the third objection,
proliferation, the nuclear fuel used by fast reactors is initially very
radioactive, making it impossible to divert to a nuclear weapons
program without an expensive, heavily shielded, off-site reprocessing
facility that would be readily detected.
In fact, the only
nuclear waste materials that will ever leave an Integral Fast Reactor
complex (which has on-site recycling) are fission products, which decay
to background levels of radiation within a few hundred years.
Unlike
conventional nuclear waste, which can last for hundreds of thousands of
years (the fourth objection), the waste from IFRs can be more readily
stored because of its small volume (150 times less than used nuclear
fuel from thermal reactors) and short storage times.
The fifth
objection, concerning greenhouse gases generated in building nuclear
power plants, has never stood up to detailed life-cycle analysis.
Renewable
energy sources (such as wind and solar) use significantly more raw
materials per unit of energy generated than even present-generation
nuclear power stations and the full life-cycle emissions, including
nuclear fuel production, are similar from both sources. When energy
storage and fossil-fuel back-up are included, wind and solar emissions
are much higher.
A possible sixth objection could be that we
don't need nuclear power when we can use renewable energy. This is a
valid objection for countries with abundant hydropower, conventional
geothermal power or biomass, the only three renewable sources of proven
reliable power that can deliver energy 24 hours a day at an acceptable
cost. Solar and wind sources, however, still rely heavily on fossil
fuels to deliver reliable, continuous energy.
At today's pace of
commercial development we won't see many fast nuclear reactors
delivering power to the grid before 2020. This will seem too late for
some, but at the present pace, non-hydro renewables will only meet 2
per cent of global energy use.
Either option, therefore, requires
radically accelerated research, development and deployment if it is to
make a difference to climate change and energy supply. What's required
is a project of Manhattan-style proportions or the audacity of the
moon-shot vision.
Let's be clear. We have the means to fix the
climate and energy crises, or at least avert the worst consequences.
New generation nuclear power, supported by an expansion of the thermal
reactor fleet, is one possible path to success and one that all nations
should support. Rationally considering energy planning requires letting
go of old-school thinking about exciting new technologies.
Martin
Nicholson is the author of Energy in a Changing Climate. Barry Brook is
professor of climate change at the University of Adelaide's Environment
Institute.
