Disposable Reactors?

Posted by Jeffrey St. Clair on August 8th, 2008 | Link

ARE ‘DISPOSABLE’ REACTORS A SAFE ENERGY SOLUTION?

By Phil McKenna
The New Scientist

Under cover of night, a fleet of nondescript freighters sets sail
protected by a naval escort. The only cargo aboard each vessel is a
mysterious cylindrical capsule some 3 metres across and 12 metres
long. Ordinarily, there would be nothing unusual about shipping goods
from the US around the world, but these 500-tonne containers are no
ordinary freight. The ships are carrying a new generation of self-
contained nuclear power plants destined for countries such as Libya,
Namibia and Indonesia — nations that the US government would not
normally trust with the custody of nuclear material.

So far this scenario is fiction, but the US-sponsored plan to make it
happen, dubbed the Global Nuclear Energy Partnership (GNEP), is real
enough. For the past two years, the US has been promoting GNEP as a
way of meeting the developing world’s burgeoning appetite for energy.

Nuclear power, the Bush administration claims, is the best option for
cutting these countries’ dependence on fossil fuels — and thus their
carbon emissions — while maintaining a secure baseload electricity
supply.

Safety and security are the key selling points for this new generation
of nuclear generators. The idea is to ship out complete nuclear power
plants — including the reactor, cooling and heat-exchange systems –
in a sealed, tamper-proof capsule that will run maintenance-free for
30 years, matching the lifetime of conventional reactors. Unpack it,
plug it into a turbine and generator connected to the electricity grid
and you’re away.

An international race to be first to ship one of these “black box”
reactors has already begun. Russia and India both have advanced plans
to supply the hundreds of small nuclear reactors to developing
countries in the coming decades. However, advocates of GNEP say that
these rival approaches are neither safe nor secure.

In April 2007, the Russian state nuclear energy company RosEnergoAtom
began building the first of a batch of 35-megawatt nuclear reactors
designed to be mounted on barges, towed to where they are needed, and
hooked up to the local electricity grid. The units will first be
deployed to provide power for the towns and cities rapidly developing
along remote stretches of Russia’s Arctic coastline. Later, the
company plans to sell them to other coastal nations too. Critics of
this approach point to their vulnerability. In particular, standard
safeguards against attacks by terrorists, such as partially burying a
reactor underground and surrounding it with high-impact concrete
walls, aren’t an option for these floating units.

The Nuclear Power Corporation of India, based in Mumbai, has built a
number of Pressurised Heavy Water Reactors (PHWR), and hopes to export
a 220-megawatt version of the reactor soon. The design has attracted
criticism on security grounds. A country looking to get its hands on
material for a nuclear weapon would find a unit like this highly
desirable. As the reactor is a “heavy-water” type, it produces large
amounts of plutonium as it burns uranium. In addition, it can be
refuelled without being shut down, which might make it easier to
conceal illicit activity from international monitoring agencies. “You
could produce quite a bit of weapons-grade material in one year,
enough for 10 bombs anyway, while you continue to operate; you’re just
moving the fuel through,” says Tom Shea of the US Department of
Energy’s Pacific Northwest National Laboratory in Richland,
Washington.

Safeguards for spent fuelProjects like these helped spur the US to
launch GNEP. Under this scheme, states that relinquish any ambition to
build conventional nuclear stations will be given the opportunity to
buy the new secure reactors instead. The UK, France, Canada, China and
Japan are among the 20 nations — many of whom are developing similar
reactors — that have signed up to the project. Participants agree to
develop designs that safeguard against the possibility that reactor
fuel could be diverted to make nuclear weapons, and to supply fresh
fuel and collect spent fuel for reprocessing or storage in a way that
ensures that none can go missing. They also undertake to share safety
and security features in their designs. Participating nations that do
not already have nuclear capacity — a growing list including Jordan,
Kazakhstan and Senegal — agree not to develop uranium enrichment and
reprocessing plants that could be used to develop material for nuclear
weapons.

Over the coming months, the US Department of Energy will be inviting
bids from the nuclear industry for a preliminary design that could be
deployed within a decade. The winning bidder will be awarded $100
million, spread over five years, as they seek a licence for their
design from the Nuclear Regulatory Commission (NRC). The competition
is designed to jump-start the US nuclear industry, which has been at a
near standstill since the accident at Three Mile Island power plant in
Pennsylvania in 1979, when loss of coolant caused the reactor to
overheat, melting part of the core and its fuel. Construction of the
winning design could begin by 2015.

Other GNEP members are also hard at work. Argentina is planning to
build prototypes for a 27-megawatt water-coooled reactor that could be
ready for production within a decade, while South Korea has a 100-
megawatt design running to a similar schedule. France has mature
designs for a water-cooled reactor with an output in the range of 100
to 300 megawatts.

When it comes to safety, one of the key features is to build a reactor
in such a way that the coolant will keep the core’s temperature under
control in all conceivable circumstances. Failure could result in
meltdown of the core and a massive release of radioactivity. Most
existing reactors use water as a primary coolant, and are fitted with
back-up systems to minimise the chances of catastrophe even if there
is a failure such as a burst pipe, locked valve or loss of power. But
even with multiple back-ups, a run of bad luck could mean that they
all fail and an accident happens.

GNEP reactors follow a new approach. “Today’s reactors are not your
grandpa’s reactors,” says Michael Driscoll, a professor of nuclear
engineering at the Massachusetts Institute of Technology. Instead of
relying on electrical or mechanical devices, the cooling systems will
be “passive”, driven entirely by phenomena such as convection or
gravity. These features are being incorporated into the International
Reactor Innovative and Secure (IRIS) project, a 335-megawatt reactor
that is seen as a front runner in the US Department of Energy’s design
competition. It is being built by an international consortium of
public and private organisations, led by veteran nuclear reactor
manufacturer Westinghouse. IRIS’s emergency cooling system exploits
convection to cycle cooling water through the reactor, dramatically
reducing the chances of a meltdown, Driscoll says.

The IRIS reactor is designed specifically for developing countries
looking for a relatively small, inexpensive and easy-to-operate
reactor that won’t overload their energy grid. “The economics and
design has to be something that fits for these countries that are
coming up to nuclear for the first time,” says IRIS’s lead engineer,
Mario Carelli. He says each IRIS unit would cost about $1 billion,
compared with roughly $7 billion for conventional gigawatt-scale
reactors.

To keep the fuel for these reactors secure, one aim of the designs is
to ensure they run as long as possible without refuelling. No one is
likely to steal fuel from inside a working reactor, but new fuel rods
in transit or stored on site are more vulnerable — and the same goes
for spent fuel on its way to be reprocessed. At least one such theft
has already occurred. In the late 1970s, two fresh fuel rods
disappeared from a research reactor in Kinshasa, the capital of the
Democratic Republic of the Congo. One of the rods was recovered in
Italy in 1998; Italian press reports suggested the Italian Mafia was
caught shipping it to an unnamed country in the Middle East. The other
has never been found. “If we start sending reactors en masse to
countries that can’t even police them, the risk of another Kinshasa -
or worse — happening could be all too high,” says Edwin Lyman, a
nuclear security specialist with the Union of Concerned Scientists in
Washington DC.

IRIS is designed to operate for up to four years without refuelling, a
big improvement on the 18 months conventional reactors require. Even
better would be a reactor that can run for its entire 30-year design
life without refuelling. Would that be possible?

A design that comes close is the Super Safe, Small and Simple, or 4S,
a sealed reactor designed by Toshiba in Japan. Toshiba is seeking an
NRC licence with a view to installing a 4S unit in Galena, a remote
town on the Yukon river in Alaska that has so far had to rely on
diesel generators for its electricity. The 4S would provide a steady
10 megawatts for 30 years, after which the entire reactor vessel would
be shipped to a fuel reprocessing facility. The reactor’s modest
output makes it ideal for remote sites like Galena, as well as
installations such as mines and desalination plants. A 50-megawatt
reactor has been designed for clients with a higher demand. But the
4S’s design does have one potential safety weakness: it uses liquid
sodium metal as its coolant. Sodium reacts violently with water –
even contact with moisture in the air could start a fire. “There is no
silver bullet, no perfect system,” says Dan Ingersoll, a GNEP program
director at the Oak Ridge National Laboratory in Tennessee. “That’s
why there are 60-plus designs under development around the world. You
solve one problem and introduce several more.”

Researchers at Lawrence Livermore National Laboratory (LLNL) in
California are pursuing a different type of reactor that runs for just
as long without refuelling. Called the Small Secure Transportable
Autonomous Reactor, or SSTAR, this is a 20-megawatt device contained
in a vessel 3 metres in diameter and 12 metres long that ships fully
assembled with a 30-year fuel supply sealed in. The unit is encased in
a tamper-proof cask protected by an array of alarms that will warn of
any attempts at interference via secure satellite radio channels.

The SSTAR unit leaves the factory with a layer of lead roughly 1 metre
thick surrounding the reactor core. After the reactor starts up, the
lead melts and from then on convection of the molten metal is enough
to carry heat away from the core. Unlike sodium, lead isn’t flammable.

“Such a reactor system would operate with minimal intervention and
little maintenance,” says Craig Smith, a project leader on SSTAR for
the LLNL. “I don’t think you could flip the switch and walk away, but
on the other hand you wouldn’t need a very large operational or
security force to maintain it.”

So how safe and secure will sealed reactors be? One thing that seems
certain is that the host country will always be able to get hold of
the fuel inside if it is determined enough. “The countries could
always kick out the inspectors, then you have to worry about
compliance,” says Hal Feiveson, a physicist and arms control expert at
Princeton University “Over 30 countries are actively considering
embarking upon nuclear power programmes. We see the trouble we are
having with Iran right now — you could imagine having five or six
Irans out there.”

There is also the possibility of a catastrophic accident. “The notion
of small, self-contained reactors where there is no advanced
industrial infrastructure or expertise, no regulatory infrastructure
for system monitoring, where emergency planning is sub-optimal or non-
existent is really a recipe for disaster,” says Lyman. Sabotage
remains a possibility, too.

Ben Ayliffe, head of anti-nuclear campaigns at Greenpeace in the UK,
thinks the whole plan is misguided. “It’s one of those ideas you look
at and ask: are these people for real?” If providing electricity-
generating technology to developing countries is our goal, then there
are far more secure technologies — including solar, wind, hydropower,
and increased energy efficiency — that don’t have the waste and
military use issues that come with spreading uranium around the world,
he says.

Ingersoll, however, sees these reactors as a positive discouragement
to the proliferation of nuclear technology compared with the
alternative. “If we say to the developing world, just wait 30 years
and we’ll give you the perfect solution to your energy needs, they are
going to say no thank you and grab whatever power sources they can,”
he says. “Renewables are not even going to come close to meeting our
current demands and won’t come anywhere near where we are expected to
go.”

He concedes that total security is probably unachievable. “We will
never have a completely proliferation-proof reactor, just like there
will never be an ‘accident-proof’ car,” he admits. But he still thinks
it’s a goal worth striving towards. “We should continue to improve the
designs, at least to the point where the consequences are
insignificant.”

Judging by the pace at which less secure alternatives are being
developed, and the urgent need for a quick source of clean energy, we
may have little choice.

Phil McKenna is a writer based in Boston

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