海上浮动核电站
南平人事局-俞敏洪语录
THERE are many things people do not
want to be built in their backyard, and
nuclear power stations are high on the list.
But what if floating reactors could
be moored
offshore, out of sight? There is plenty of water
to keep them cool
and the electricity they
produce can easily be carried onshore by undersea
cables. Moreover, once the nuclear plant has
reached the end of its life it can
be towed
away to be decommissioned. Unusual as it might
seem, such an idea
is gaining supporters in
America and Russia.
The potential benefits of
building nuclear power stations on floating
platforms,
much like those used in the
offshore oil-and-gas industry, were recently
presented to a symposium hosted by the
American Society of Mechanical
Engineers by
Jacopo Buongiorno, Michael Golay, Neil Todreas and
their
colleagues at the Massachusetts
Institute of Technology, along with others
from the University of Wisconsin and Chicago
Bridge & Iron, a company
involved in both the
nuclear and offshore industries.
Floating nuclear power stations (like the one
in the illustration above) would
have both
economic and safety benefits, according to the
researchers. For one
thing, they could take
advantage of two mature and well-understood
technologies: light-water nuclear reactors and
the construction of offshore
platforms, says
Dr Buongiorno. The structures would be built in
shipyards
using tried-and-tested techniques
and then towed several miles out to sea and
moored to the sea floor.
Keeping cool
Offshore reactors would help overcome the
increasing difficulty of finding sites
for new
nuclear power stations. They need lots of water,
so ideally should be
sited beside an
ocean, lake or river. Unfortunately, those are
just the places
where people want to live, so
any such plans are likely to be fiercely opposed
by locals.
Another benefit of being
offshore is that the reactor could use the sea as
an
“infinite heat sink”, says Dr Buongiorno.
The core of the reactor, lying below
the
surface, could be cooled passively without relying
on pumps driven by
electricity, which could
fail. In the nuclear disaster in Japan in 2011 a
powerful
earthquake off the coast created a
tsunami that inundated the Fukushima
Dai-ichi
nuclear power plant, wrecking the backup power
generators used to
keep the cooling pumps
going. This set off a meltdown in three of the
plant’s
reactors.
A floating nuclear power
station would be protected against earthquakes and
tsunamis. The expanse of the ocean would
shield the structure from seismic
waves in the
seabed, says Dr Buongiorno, and, provided the
power station
was moored in about 100 metres
of water, the swell from a tsunami should not
be large enough to cause any serious damage.
At the end of its service life, a floating
nuclear power station could be towed to
a
specially equipped yard where it could be more
easily dismantled and
decommissioned. This is
what happens to nuclear-powered ships.
Rosatom, a Russian state-controlled energy
company, is already building a
floating
nuclear power station. This is the
Akademik
Lomonosov
, a large barge
carrying a pair
of nuclear reactors capable of together generating
up to 70
megawatts (MW)—enough to power a
small town. The vessel is due to be
completed
in 2016 and is said to be the first of many. Some
people believe the
project’s primary mission
is to provide power for the expansion of Russia’s
oil-and-gas industry in remote areas,
including the Arctic.
The American researchers
think there is no particular limit to the size of
a
floating nuclear power station and that even
a 1,000MW one—the size of
some of today’s
largest terrestrial nuclear plants—could be built.
They
believe the floating versions could be
designed to meet all regulatory and
security
requirements, which would include protecting the
structure from
underwater attack, says Dr
Todreas.
The idea is not new. In the late
1960s
Sturgis
, a converted Liberty ship
containing a 10MW nuclear reactor, was used to
provide electricity to the
Panama Canal Zone,
which faced a power shortage. In the 1970s there
was a
plan to build 1,200MW nuclear power
stations off America’s east coast.
These would
float on giant concrete barges surrounded by a
breakwater. The
scheme got as far as
constructing a huge manufacturing yard near
Jacksonville, Florida. But the idea faced
opposition and was scrapped, in part
because
of technical and regulatory uncertainties. A newer
generation of
floating nuclear reactors
would be safer and cheaper, but they are still
unlikely
to set sail without a fight