An Introduction to Argonne National Laboratory's
INTEGRAL FAST REACTOR (IFR) PROGRAM
The Integral Fast Reactor (IFR) program was the nation's premier research and
development effort focused on the basic design concepts and testing the next
generation nuclear power plant. The IFR development work provides solutions in
the areas of concern for today's nuclear plants. These solutions are integrated
into a single, coherent nuclear plant concept. The work at Argonne included
real-world testing, not just computer simulation, so that the results are not
open to question. This was being done to allow larger, commercial plants to be
built with confidence.
The IFR work included research and development in plant safety, waste,
transportation, economics, prevention of the diversion of nuclear materials, and
includes a plant for which the fuel is so plentiful that fuel costs cannot
reasonably outrun inflation. These important areas of focus are all included in
the IFR, hence the name "Integral".
The objective for this work was to determine the best approach for the design of
the next generation nuclear plant -- to build on the excellent record of today's
nuclear plant, but to simplify, integrate, and take maximum advantage of natural
phenomenon for protection and operation. A system has been worked out in which
a new fuel type has allowed major advances in improving safety, economics, and
minimizing the need for waste storage.
It is now clear that the IFR effort would have resulted in a "new and improved" nuclear
plant -- one that can serve as the electric power source of choice for an energy
hungry, but environmentally aware and concerned world.
The following describes important features of the IFR and some of the facilities
at Argonne West that were devoted to the development of the IFR concept. The IFR work
required the analytical and design capabilities of numerous people at the main
headquarters of Argonne, near Chicago, and the developmental, operational, and
Testing Capabilities at Argonne - West in Idaho.
The IFR gains safety advantages through a combination of metal fuel (an alloy of
uranium, plutonium, and zirconium), and sodium cooling. By providing a fuel
which readily conducts heat from the fuel to the coolant, and which operates at
relatively low temperatures, the IFR takes maximum advantage of expansion of the
coolant, fuel, and structure during off-normal events which increase
temperatures. The expansion of the fuel and structure in an off-normal situation
causes the system to shut down even without human operator intervention.
In April of 1986, two special tests were performed on the Experimental Breeder
Reactor II (EBR-II), in which the main primary cooling pumps were shut off with
the reactor at full power (62.5 Megawatts, thermal) - By not allowing the normal
shutdown systems to interfere, the reactor power dropped to near zero within
about 300 seconds. No damage to the fuel or the reactor resulted.
This test demonstrated that even with a loss of all electrical power and the
capability to shut down the reactor using the normal systems, the reactor will
simply shut down without danger or damage. The same day, this demonstration was
followed by another important test.
With the reactor again at full power, flow in the secondary cooling system was
stopped. This test caused the temperature to increase, since there was nowhere
for the reactor heat to go. As the primary (reactor) cooling system became
hotter, the fuel, sodium coolant, and structure expanded, and the reactor shut
down. This test showed that an IFR type reactor will shut down using inherent
features such as thermal expansion, even if the ability to remove heat from the
primary cooling system is lost. Events such as the loss of water to the steam
system would cause a condition such as the test demonstrated.
Another major feature of the IFR concept is that the reactor uses a coolant,
sodium, which does not boil during normal operation nor even in overpower
transients such as described above. This means that the coolant is not under
significant pressure. When coolant is not under pressure, the reactor can be
placed in a "pool" of coolant, contained in a double tank, so that there is no
real possibility for a loss of coolant. Even if the normal pumps are lost, some
coolant flow through the reactor occurs due to natural convection.
The features described above allow for greater simplification of a nuclear plant,
resulting in cost savings, greater ease in operation, and a safety system that
relies on natural phenomenon that cannot be defeated by human error.
Discussions on waste, nearly unlimited fuel supply, transportation, and a nearly
diversion-proof fuel all hinge on the fuel type and the fuel reprocessing scheme.
To describe the waste advantages, fuel reprocessing will first be described.
Reprocessing of fuel is a key requirement of the IFR. However, IFR reprocessing
is very different from processes which have been proposed or which are in use in
Basically, reprocessing IFR fuel consists of two simple steps: 1. fission
fragments are removed from the fuel, and 2. unused fuel is recovered, along with
the transuranic elements (sometimes called actinides). Normally, the transuranic
elements would go to the waste stream with the fission products, but in the IFR,
they are kept with the fuel and sent back to the reactor to also serve as fuel.
In the above description, note that the waste stream consists of only the fission
products. The result is that instead of a waste that remains radioactive for
many thousands of years, as would be the case if the transuranic elements were
present, the radioactivity in the waste will decay to a value less than that of
the original uranium ore in about 200 years.
An additional advantage to the waste side of the IFR operation is that the IFR
plant produces less low-level waste than today's nuclear plants. The sodium
coolant used in the IFR does not corrode the piping or structure, and, as a
result, there are no radioactive corrosion products to remove from the primary
system and send to a low-level radioactive waste repository.
The fission product waste from an IFR type plant will amount to about 1700 pounds
of waste per year for a plant of about 1000 megawatts electric output. This is
in contrast to the waste from an equivalent coal plant of about 1,275,000 tons
per year. These figures are for a plant that operates about 70 percent of the
Today, there is concern about the safety of shipping radioactive substances over
the nation's highways. Whether the concern is warranted, based on comparisons
to other hazardous materials that are shipped in huge quantities, will not be
discussed here. It appears that the public perception is that radioactive
shipments should be minimized.
The IFR reactor is a breeder reactor, that is, during operation, it can convert
materials (such as uranium 238) which cannot be used in today's reactors for
fuel, to a very good fuel, plutonium 239. The conversion takes place in the
reactor. In the fuel recycle process, plutonium is separated from the fission
products and returned to the reactor (along with other transuranic elements)
where it is fissioned to produce power. (NOTE: all reactors create some
plutonium, today's reactors receive about 30% of their power from plutonium
created and then fissioned within the reactor)
The breeding process reduces the requirement for fissile materials being
transported to the plant. Only the original fuel loading must be shipped in, and
a quantity of uranium 238 -- which is not a fissile material. These shipments
are made at the beginning life of the IFR plant, and no further fuel shipments
into the plant need be made for the entire plant lifetime, approximately 60
years. The uranium 238 necessary to fuel the plant for its lifetime would make
a cube of less than 6 feet per side.
Shipment of waste is also reduced. The volume is such that the radioactive waste
can be stored at the plant site for the entire life of the plant, and then
shipped at one time to a waste repository.
For a new power source to be viable, the cost of power must be competitive with
today's power systems. The proof of costs in any project only comes when full-
sized systems are built and operated. Although no full-sized IFR plant has been
built, several facts suggest that the IFR will be very economic.
Costs of today's nuclear plants are just slightly above that of coal as a
national average. Several nuclear plants have operated with costs significantly
below that of coal however. A new IFR should cost less than either a new nuclear
(typical of today's technology) or coal plant based on the following.
The IFR does not require some of the complex systems that today's reactors
require. Examples include the low level radwaste cleanup station, the emergency
core cooling system, and fewer control rod drives and control rods for comparable
power. Because of the low pressure in the sodium systems, less steel is required
for the plant piping and reactor vessel. There are studies that suggest that the
reactor containment will be less massive. Other cost savings will be made
because the IFR does not require the services of the Isotopic Separation Plants
for fuel enrichment.
Additional costs to the IFR include the integral fuel reprocessing capability,
and a secondary sodium system (but the IFR fuel process costs are somewhat offset
by the extremely low cost for raw fuel and the improved waste product).
Some studies have been done which indicate that an IFR would be very economical
and competitive to build, own, and operate, but the final proof of economics can
only come in the construction and operation of a commercial sized plant.
The diversion of nuclear fuel for the purpose of making bombs has been a concern,
although presently the handling and destruction of nuclear weapons material is
the primary issue. In the IFR, the nature of the fuel reprocessing is such that
the fuel remains highly radioactive at all times. Fuel can only be handled in
shielded cells or transported in casks weighing many tons. In addition, because
the fuel recycle facility is located on-site, there is no transportation of
nuclear which could create an opportunity for diversion. In any event, IFR fuel
is not suitable for weapons without extensive processing in very expensive
facilities. The potential also exists for the IFR to use weapons material for
fuel, thus eliminating it, while producing electricity.
"Limitless" Fuel Supply
There is sufficient fuel to power IFR type facilities for well over 100 thousand
years. This results because the IFR is a breeder reactor which can utilize
uranium 238. Today's reactors only use uranium 235 which is less than 1% of the
uranium found in nature.
The IFR, with its fuel reprocessing capability, can use all the uranium. There
is enough uranium that has been mined and placed in barrels (uranium 238) for
IFR-type plants to provide all the electricity for the United States for over 500
years -- without mining. Also, the IFR can likely reprocess the spent fuel from
today's reactors, and use the recovered materials for fuel.
Uranium is as abundant in the earth as many of the commonly used materials such
as bismuth, cadmium, mercury, silver, etc. In fact the uranium in a typical 1
ton block of granite (concentration of about 5 ppm) is the energy equivalent (if
used in the IFR) of 10 tons of coal! The abundance of uranium suggests that its
price will likely not increase as a fuel material for the foreseeable future.
The IFR story is important to the world because the very foundation of an
industrial society depends on inexpensive and abundant energy. The IFR can
provide the base energy supplies needed, and with very little impact on the
environment. Mining of fuel for the IFR is not needed for several hundred years.
The IFR does not produce gases or other effluents that would harm the biosphere.
The long-term waste problem, of concern today, no longer is a problem with the
IFR. In addition, the IFR should be economic and a safe, easy to operate plant.
These features make the IFR the candidate for the next generation nuclear power
-- standard disclaimers apply --