Fast Neutron Reactors
Nuclear Waste can be a solution not a problem
Advanced Fast Neutron Reactors (AFR) are fast breeder reactors
that can use nuclear “waste” for fuel — the spent
nuclear fuel that has been discarded from conventional nuclear
plants can power AFR's, producing clean electricity while destroying
radioactive waste.
“Fast-neutron reactors could extract much more energy from recycled
nuclear fuel, minimize the risks of weapons proliferation and markedly
reduce the time nuclear waste must be isolated.
“If developed sensibly, nuclear power could be truly sustainable
and essentially inexhaustible and could operate without
contributing to climate change. In particular, a relatively new
form of nuclear technology could overcome the principal
drawbacks of current methods—namely, worries about reactor
accidents, the potential for diversion of nuclear fuel into
highly destructive weapons, the management of dangerous,
long-lived radioactive waste, and the depletion of global reserves
of economically available uranium. This nuclear fuel cycle would combine
two innovations: pyrometallurgical processing
(a high-temperature method of recycling reactor waste
into fuel) and advanced fast-neutron reactors capable of burning
that fuel. With this approach, the radioactivity from the
generated waste could drop to safe levels in a few hundred
years, thereby eliminating the need to segregate waste for tens
of thousands of years...”
Smarter Use of Nuclear Waste 
size: 575 Kb - 8 pages
By William H. Hannum,
Gerald E. Marsh and
George S. Stanford
Fast Neutron Reactors — “Several
countries have research and development programs for improved Fast Breeder
Reactors (FBR), which are a type of Fast
Neutron Reactor. These use
the uranium-238 in reactor fuel as well as the fissile U-235 isotope used
in most reactors.
“Natural uranium contains
about 0.7 % U-235 and 99.3 % U-238. In any reactor the U-238 component
is turned into several isotopes of plutonium during its
operation. Two of these, Pu 239 and Pu 241, then undergo fission in the
same way as U 235 to produce heat. In a fast
neutron reactor this process
is optimised
so that it can 'breed' fuel, often using a depleted uranium blanket around
the core. FBRs can utilise uranium at least 60 times more efficiently
than a normal reactor.”
—Advanced Nuclear Power Reactors
World Nuclear Association
“The American Nuclear Society believes
that the development and deployment of advanced
nuclear reactors based on fast-neutron fission technology is important
to the sustainability,
reliability, and security of the world’s long-term energy supply.
Of the known and proven energy
technologies, only nuclear fission can provide the large quantities
of energy required by
industrial societies in a sustainable and environmentally acceptable
manner.
“Natural uranium mined from the earth's crust is composed
primarily of two isotopes: 99.3% is U-
238, and 0.7% is the fissile U-235. Nearly all current power reactors
are of the “thermal neutron” design, and their capability
to extract the potential energy in the uranium fuel is limited to less
than 1% of that available. The remainder of the potential energy is left
unused in the spent fuel
and in the uranium, depleted in U-235, that remains from the process
of enriching the natural
uranium in the isotope U-235 for use in thermal reactors. With known
fast reactor technology,
this unutilized energy can be harvested, thereby extending by a hundred-fold
the amount of
energy extracted from the same amount of mined uranium.
“Fast reactors can convert U-238 into fissile material at
rates faster than it is consumed making it
economically feasible to utilize ores with very low uranium concentrations
and potentially even
uranium found in the oceans.1–3 A suitable technology
has already been proven on a small scale.4
Used fuel from thermal reactors and the depleted uranium from the enrichment
process can be
utilized in fast reactors, and that energy alone would be sufficient
to supply the nation’s needs
for several hundred years.
“Fast reactors in conjunction with fuel recycling can diminish
the cost and duration of storing and
managing reactor waste with an offsetting increase in the fuel cycle
cost due to reprocessing and
fuel refabrication. Virtually all long-lived heavy elements are eliminated
during fast reactor
operation, leaving a small amount of fission product waste that requires
assured isolation from
the environment for less than 500 years.4
“Although fast reactors do not eliminate the need for international
proliferation safeguards, they
make the task easier by segregating and consuming the plutonium as it
is created. The use of
onsite reprocessing makes illicit diversion from within the process highly
impractical. The
combination of fast reactors and reprocessing is a promising option for
reasons of safety,
resource utilization, and proliferation resistance.5
“Reaping the full benefits of fast reactor technology will
take a decade or more for a
demonstration reactor, followed by buildup of a fleet of operating power
stations. For now and in
the intermediate-term future, the looming short-term energy shortage
must be met by building
improved, proven thermal-reactor power plants. To assure longer-term
energy sustainability and
security, the American Nuclear Society sees a need for cooperative international
efforts with the
goal of building a fast reactor demonstration unit with onsite reprocessing
of spent fuel.”
American Nuclear Society Position Statement
Fast Reactor Technology: A Path to Long-Term Energy Sustainability
size: 30 Kb - 2 pages
Is nuclear energy renewable?
Generally “renewable” relates to harnessing energy from
natural forces which are renewed by natural processes, especially wind,
waves, sun and
rain, but also heat from the Earth's crust and mantle. And
because it shares many attributes with technologies harnessing
these natural forces — for instance radioactive decay produces much
of the heat harnessed
geothermally, nuclear energy is sometimes classified with them.
But there are other reasons to call nuclear
energy “renewable”. In any nuclear reactor the input fuel is normally uranium-235 (U-235) which is part of a much larger mass of uranium - mostly U-238. This U-235 is progressively 'burned' over about three years to yield a lot of heat. But about one third of the energy yield comes from something which is not initially loaded in: plutonium 239 (Pu-239), which behaves almost identically to U-235. This
is because the fission of U-235 causes some of the U-238 to turn into
Pu-239, so about half of the U-235 used actually renews itself by producing Pu-239
from the otherwise waste material U-238. So, it's partly Renewable in
this
situation.
This raises the possibility of whether U-235 can be made fully Renewable. In fact, it can, by optimising the process in another kind of reactor which can be configured to "breed" more Pu-239 than it consumes (by way of U-235 + Pu-239), so that the system can run indefinitely. While it can produce more fuel than it uses, there does need to be steady input of reprocessing activity to separate the fissile plutonium from the uranium and other materials. This is fairly capital-intensive but well-proven and basically straightforward. The
used fuel from the whole process is recycled and the usable part of it
increases incrementally.
Apart from this there is thorium, which is four times as abundant as
uranium. Using a similar process to the breeder reactor, thorium can
produce U-233, which is fissile. This process is not yet commercialised,
but it works and if there were ever a pressing need for it, development
would be accelerated. —Sustainable
Energy World Nuclear Association
Future Nuclear
Fission Power Plant Technology — Generation IV
Scientists at Argonne
National Laboratory are developing a new generation of Nuclear Reactors.
The technology is called IFR which stands for Integral Fast Reactor. The
technology is also called AFR which stands for Advanced Fast Reactor.
Read what a nuclear physicist says about Integral Fast Reactors:
Integral
Fast Reactors: Source of Safe, Abundant, Non-Polluting Power by George
S. Stanford, Ph.D. nuclear reactor physicist, now retired from Argonne
National Laboratory after a career of experimental work pertaining to
power-reactor safety.
“There's another huge benefit, of course. If nothing
better comes along, the IFR can supply the world with pollution-free energy
for thousands of years.” — George Stanford, Ph.D.
Passively
safe reactors rely on nature to keep them cool by David Baurac, director
of public information for the Argonne National Laboratory.
Argonne's advanced fast reactor (AFR) has demonstrated its passive
safety conclusively on a working prototype. "Back in 1986, we
actually gave a small prototype advanced fast reactor a couple of
chances to melt
down," says Argonne nuclear engineer Pete Planchon, who led
the 1986 tests. "It politely refused both times."
Read more about Integral/Advanced Fast Reactors:
Dr.
Charles Till Nuclear physicist and associate lab director at Argonne
National Laboratory West in Idaho. He is co-developer of the Integral
Fast Reactor, an inherently safe nuclear reactor with a closed fuel cycle.
“The radioactive isotopes in spent nuclear fuel are of two types:
fission products and actinides. The fission products as a group have
an effective half-life of about thirty years. It takes only about
500 years for their toxicity to drop below that of the natural uranium
ore
from which their parent atoms came.
“The actinides, on the other hand, have long half-lives, and their
toxicity level is orders of magnitude greater for millions of years.
In pyroprocessing, the actinides are easily recovered and recycled back
into the reactor. This reduces the effective lifetime of the nuclear
waste from tens of thousands of years to a few hundred, and meanwhile
energy is generated by fissioning the actinides.
“A repository is still needed, but its performance specifications
can be much less stringent without the long-lived actinides. Furthermore,
the repository's capacity is increased substantially because the long-term
heat source is eliminated. And the disposal site does not become a geological
plutonium deposit, waiting to be mined by a would-be bomb-maker in the
distant future, when the isotopic suitability of the plutonium for weapons
will have improved considerably.
“Nonproliferation: The nuclear materials in the
closed fuel cycle cannot be used directly in weapons, because pyroprocessing
is unable to separate pure plutonium. Instead, the plutonium is mixed
at all times with uranium, other actinides, and fission products.
The mixture is protected against theft or unauthorized diversion because
it is dauntingly radioactive and must be handled remotely with sophisticated,
specialized equipment.
“Pyroprocessing systems are compact, and the fuel-cycle facility
can easily be collocated with the reactor, all but eliminating the need
to transport nuclear fuel.”
Yoon I. Chang
Adapted from a talk delivered at Argonne National Laboratory, September
28, 2001 Titled, Advanced
Fast Reactor: A Next Generation Nuclear Energy Concept
Argonne
National Laboratory, along with the Idaho
National Laboratory (INL), is leading
U.S. participation in the
Generation IV project, an international effort to develop the
next generation of Closed fuel cycle advanced nuclear reactors.
Six Generation IV technology
concepts have been selected for R&D
With a robust R&D effort, most of those concepts could be developed
and deployed by the year 2020. And each is aimed at meeting projected
power needs in the mid-21st century. For example, several concepts—most
prominently, the very-high-temperature gas-cooled reactor—have
a higher output temperature and are therefore attractive for process heat
applications. These concepts also would be well-suited to produce hydrogen
in quantity and at an attractive price. Nuclear power currently is one
of the most attractive means of large-scale production of hydrogen.
Five of the six Generation IV technology concepts are being pursued
at varying levels of effort based on their
technology
status and potential to meet program and national goals. Two are thermal
neutron spectrum systems (Very-High-Temperature Reactor (VHTR) and Supercritical-Water-Cooled
Reactor (SCWR)) with coolants and temperatures that enable hydrogen or
electricity production with high efficiency, and three are fast
neutron spectrum systems (Gas-Cooled (GFR), Lead-Cooled (LFR), and Sodium-Cooled
(SFR) fast reactors) that will enable more effective management of actinides
through recycling of most components in the discharged fuel.
The U.S.
is not currently researching the molten salt reactor (MSR). Japan is
focusing on the sodium-cooled reactor (MSR), with its significant potential
for recycling of spent nuclear fuel in the near future.
The six Gen IV reactor concepts shown with illustrations:
Gas-Cooled
Fast Reactor (GFR)
features a fast-neutron-spectrum, helium-cooled reactor and closed fuel
cycle.
Molten
Salt Reactor (MSR)
produces fission power in a circulating molten salt fuel mixture with
an epithermal-spectrum reactor and a full actinide recycle fuel cycle.
Sodium-Cooled
Fast Reactor (SFR)
features a fast-spectrum, sodium-cooled reactor and closed fuel cycle
for efficient management of actinides and conversion of fertile uranium.
Lead-Cooled
Fast Reactor (LFR)
features a fast-spectrum lead or lead/bismuth eutectic liquid metal-cooled
reactor and a closed fuel cycle for efficient conversion of fertile uranium
and management of actinides.
Supercritical-Water-Cooled
Reactor (SCWR)
is a high-temperature, high-pressure water-cooled reactor that operates
above the thermodynamic critical point of water (374 degrees Celsius,
22.1 MPa, or 705 degrees Fahrenheit, 3208 psia).
Very-High-Temperature
Reactor (VHTR)
a graphite-moderated, helium-cooled reactor with a once-through uranium
fuel cycle, designed to supply heat with core outlet temperatures of 1,000
degrees Celsius, which enables applications such as hydrogen production
or process heat for the petrochemical industry or others.
INL
team helps pave way to Generation IV reactor “Fourth generation
nuclear reactors, the nuclear power plants of tomorrow, will provide
safer, less expensive and more environmentally friendly energy. A critical
step in developing new Very High Temperature Reactors (VHTR) is certifying
the graphite that is used in many parts of the reactor's core. In recent
years, it has become necessary to develop new nuclear-grade graphite
and certify it for use in the next generation of gas-cooled nuclear
reactors... nuclear experts envision two different versions of gas
cooled VHTRs for next-generation use. Both designs will require large
amounts of high-quality graphite.”
Reference Resources:
World Uranium Reserves
Generation-IV
Roadmap—Report of the Nuclear Fuel Cycle
— From the U.S. Department of Energy (DOE) website.
337 page Adobe PDF document (size: 4 MB)
Chapter One, Section 1.3: Availability of Ore — Fueling Generation IV.
1.3.4 Sustainability Potential “For such recycle based fuel
cycles, if exploited fully, at least a millennium of energy supply can
be foreseen from the earth’s endowment of economically recoverable
uranium ore listed in Table 1.3. Likewise, the energy potential of the
earth’s endowment of thorium is greater still. Thus the resource
base is sufficient to support the Gen-IV sustainability goal—given
that the fuel cycles and reactor types are deployed to fully exploit
those resources.”
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