Fast breeder reactor
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Template:TOCright The fast breeder or fast breeder reactor (FBR) is a fast neutron reactor designed to breed fuel by producing more fissile material than it consumes. The FBR is one possible type of breeder reactor.
As of 2006, all large-scale FBR power stations have been liquid metal fast breeder reactor (LMFBR) reactors cooled by liquid sodium. These have been of one of two designs:
- Loop type, in which the primary coolant is circulated through primary heat exchangers external to the reactor tank (but within the biological shield owing to the presence of radioactive sodium-24 in the primary coolant).
- Pool type, in which the primary heat exchangers and circulators are immersed in the reactor tank.
Prototype FBRs have also been built cooled by other liquid metals such as mercury, lead and NaK, and one generation IV reactor proposal is for a helium cooled FBR.
Image:LMFBR schematics.pngFBRs usually use a mixed oxide fuel core of up to 20% plutonium dioxide (PuO2) and at least 80% uranium dioxide (UO2). The plutonium used can be from reprocessed civil or dismantled nuclear weapons sources. Surrounding the reactor core is a blanket of tubes containing non-fissile uranium-238 which, by capturing fast neutrons from the reaction in the core, is partially converted to fissile plutonium 239 (as is some of the uranium in the core), which can then be reprocessed for use as nuclear fuel. No moderator is required as the reactions proceed well with fast neutrons. Early FBRs used metallic fuel, either highly enriched uranium or plutonium.
Fast reactors typically use liquid metal as the primary coolant, to cool the core and heat the water used to power the electricity generating turbines. Sodium is the normal coolant for large power stations, but lead and NaK have both been used successfully for smaller generating rigs. Some early FBRs used mercury. One advantage of mercury and NaK is that they are both liquids at room temperature, which is convenient for experimental rigs but less important for pilot or full scale power stations.
Liquid sodium leaving the core contains radioactive sodium-24. This is a short-lived radioisotope, but its presence necessitates keeping the entire primary coolant loop within a biological shield.
Water cannot be used as the primary coolant since it would soak up neutrons, hampering the breeding, however a heavy water moderated thermal breeder reactor using thorium to produce uranium-233 is theoretically possible, see below.
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FBR generating plants
History
FBRs have been built and operated in the USA, the UK, France, the former USSR, India and Japan. As of 2004, a prototype FBR was under construction in China, while another experimental FBR in Germany was built but never operated.
USA
On December 20, 1951, the fast reactor EBR-I (Experimental Breeder Reactor-1) at the Idaho National Engineering and Environmental Laboratory in Idaho Falls, Idaho produced enough electricity to power four light bulbs, and the next day produced enough power to run the entire EBR-I building. This was a milestone in the development of nuclear power reactors.
The next generation experimental breeder was EBR-II (Experimental Breeder Reactor-2), which went into service at the INEEL in 1964 and operated until 1994. It was designed to be an "integral" nuclear plant, equipped to handle fuel recycling onsite. It typically operated at 20 megawatts out of its 62.5 megawatt maximum design power, and provided the bulk of heat and electricity to the surrounding facilities.
The world's first commercial LMFBR, and the only one yet built in the USA, was the 94MWe Unit 1 at Enrico Fermi Nuclear Generating Station. Designed in a joint effort between Dow Chemical and Detroit Edison as part of the Atomic Power Development Association consortium, groundbreaking in Lagoona Beach, Michigan (near Monroe, Michigan) took place in 1956. The plant went into operation in 1963. It shut down on October 5, 1966 due to high temperatures caused by a loose piece of zirconium which was blocking the molten sodium coolant nozzles. Partial melting damage to six subassemblies within the core was eventually found. (This incident was the basis for a controversial book by investigative reporter John G. Fuller titled We Almost Lost Detroit.) The zirconium blockage was removed in April of 1968, and the plant was ready to resume operation by May of 1970, but a sodium coolant fire delayed its restart until July. It subsequently ran until August of 1972 when its operating license renewal was denied.
The Clinch River Breeder Reactor, championed by Al Gore, was announced in January, 1972. A government/business cooperative effort, construction proceeded fitfully. Funding for this project was killed by Congress on October 26, 1983.
The Fast Flux Test Facility, first critical in 1980, is not a breeder but is a sodium-cooled fast reactor. It is now (2005) in cold standby.
UK
The UK fast reactor program was conducted at Dounreay, Scotland, from 1957 until the program was cancelled in 1994. Three reactors were constructed, two of them fast neutron power reactors, and the third, DMTR, being a heavy water moderated research reactor used to test materials for the program. Fabrication and reprocessing facilities for fuel for the two fast reactors and for the test rigs for DMTR were also constructed onsite.
Dounreay Fast Reactor (DFR) achieved its first criticality in 1959. It used NaK coolant and produced 14MW of electricity. This was followed by the sodium-cooled 250 MWe Prototype Fast Reactor (PFR) in the 1970s. PFR was closed down in 1994 as the British government withdrew major financial support for nuclear energy development, DFR and DMTR both having previously been closed.
France
France's first fast reactor, Rapsodie first achieved criticality in 1967. Built at Cadarache near Aix-en-Provence, Rapsodie was a loop-type reactor with a thermal output of 40MW and no electrical generation facilities, and closed in 1983.
This was followed by the 233 MWe Phénix, grid connected since 1973 and still operating, both as a power reactor and more importantly as the centre of work on destruction of nuclear waste by transmutation.
Superphénix, 1200 MWe, entered service in 1984 and as of 2006 remains the largest FBR yet built. It was shut down in 1997 due to polical commitement of the left government.
Germany
Germany has built two FBRs, but both were closed in 1991 without the larger ever having achieved criticality.
KNK-II was converted from a thermal reactor, KNK-I, which had been used to study sodium cooling. KNK-II first achieved criticaiity as a fast reactor in 1977, and produced 20MWe.
Construction of the 300MWe SNR-300 at Kalkar in North Rhine-Westphalia was completed in 1985, but owing to political pressure it was never operated. The plant was maintained and staffed until a decision to close it was finally made in 1990, and has since been decommissioned.
USSR
The Soviet Union constructed a series of fast reactors, the first being mercury cooled and fueled with plutonium metal, and the later plants sodium cooled and fueled with plutonium oxide.
BR-1 (1955) was 100w (thermal) was followed by BR-2 at 100kW and then the 5MW BR-5.
BOR-60 (first criticality 1969) was 60 MW, with construction started in 1965.
BN-350 (1973) was the first full-scale Soviet FBR. Constructed on the Mangushlak Peninsular in Kazakstan and on the shore of the Caspian Sea, it supplied 130MW of electricity plus 80,000 tonnes per day of desalinated fresh water to the city of Aktau. Its total output was regarded as the equivalent of 350MWe, hence the designation.
BN-600 (1986) is 1470MWth / 600MWe.
At the time of the break up of the Soviet Union, plans were well underway for the construction of two larger plants, BN-800 (800 MWe) at Beloyarsk and BN-1600 (1600 MWe).
Japan
Japan has built one FBR, Monju, in Tsuruga, Fukui Prefecture. Monju is a sodium-cooled, MOX-fueled loop type reactor with 3 primary coolant loops, producing 714 MWt / 280 MWe.
Monju began construction in 1985 and first achieved criticality in April 1994. It was closed in December 1995 following a sodium leak and fire in a secondary cooling circuit, and is expected to restart in 2008.
India
India has an active development program featuring both fast and thermal breeder reactors.
India’s first 40 MWt Fast Breeder Test Reactor (FBTR) attained criticality on 18th October 1985. Thus India becomes the sixth nation having the technology to built and operate a FBTR after US, UK, France, Japan and the former USSR.
India has developed and mastered the technology to produce the plutonium rich U-Pu mixed carbide fuel. This can be used in the Fast Breeder Reactor.
At present the scientists of the Indira Gandhi Centre for Atomic Research (IGCAR), one of the nuclear R&D institutions of India, are engaged in the construction of another FBR - the 500 MWe prototype fast breeder reactor- at Kalpakkam, near Chennai.
India has the capability to use Thorium Cycle based processes to extract nuclear fuel. This is of special significance to the Indian nuclear power generation strategy as India has the world's largest reserves of thorium — about 360,000 tones — that can fuel nuclear projects for an estimated 2,500 years. But the hitch is with the expensive nature of the construction of Fast Breeder Reactor in comparison with the Pressurised Heavy Water Reactors (PHWR) in use.
This is one of the main reasons why India looks for the cheaper option - Uranium fuel.
India and the US have signed a deal (July 2005) for nuclear energy cooperation. President George W. Bush, in his early March 2006 trip to New Delhi, India, reiterated the Nuclear Cooperation to aid India's growth. This is part of the Indo-US strategic initiate Next Steps in Strategic Partnership (NSSP). The Key theme of the agreement is the separation of the Indian military and civilian nuclear programs. The bill pushed by President Bush is expected to pass through the US Congress (midyear 2006), which has final authority to waive, on unique criteria which President Bush enunciated, such Nuclear Energy Cooperation with a non-signatory to the Nuclear Non-Proliferation Treaty.
See also
Future plants
As of 2003 one indigenous FBR was planned for India, and another for China using Soviet technology.
South Korea is developing a design for a standardised modular FBR for export, to complement the standardised PWR (Pressurized Water Reactor) and CANDU designs they have already developed and built, but has not yet committed to building a prototype.
The FBR program of India includes the concept of using fertile thorium-232 to breed fissile uranium-233. India is also pursuing the thermal breeder reactor again using thorium. A thermal breeder is not possible with purely uranium/plutonium based technology. Thorium fuel is the strategic direction of the power program of India, owing to their large reserves of thorium, but worldwide known reserves of thorium are also some three times those of uranium.
The BN-600 (Beloyarsk NNP in the town of Zarechny, Sverdlovsk Oblast) is still operational. A second reactor (BN-800) is scheduled to be constructed before 2015 [1].
On February 16, 2006 the U.S., France and Japan signed an "arrangement" to research and develop sodium-cooled fast reactors in support of the Global Nuclear Energy Partnership. [2]
Economics
The breeding of plutonium fuel in FBRs, known as the plutonium economy, was for a time believed to be the future of nuclear power. It remains the strategic direction of the power program of Japan. However, cheap supplies of uranium and especially of enriched uranium have made current FBR technology uncompetitive with PWR and other thermal reactor designs. PWR designs remain the most common existing power reactor type and also represent most current proposals for new nuclear power stations.
Proliferation
It is generally agreed that the FBR poses a greater risk of proliferation of nuclear weapons than light water-moderated reactors. Water-moderated reactors must shutdown and refuel every four months or less to produce weapons grade plutonium, relatively pure Pu-239, because the level of Pu-240 in the fuel increases over time. Pu-240 undergoes spontaneous fission at a relatively high rate and is unsuitable for nuclear weapons production. An FBR can more easily produce weapons grade material, depending on its design. However, to date all known weapons programs have used far more easily built thermal reactors to produce plutonium, and there are some designs such as the SSTAR which avoid proliferation risks by both producing low amounts of plutonium at any given time from the U-238, and by producing three different isotopes of plutonium (Pu-239, Pu-240, and Pu-242) making the plutonium used infeasible for atomic bomb use. Dirty bombs would still be a possibility, although ordinary high-level radiation waste can be used for this purpose as well.
Thorium fueled reactors may pose a slightly higher proliferation risk than uranium based reactors. The reason for this is that while Pu-239 will fairly often fail to fission on neutron capture, producing Pu-240, the corresponding process in the Thorium cycle is relatively rare. Thorium-232 converts to U-233, which will almost always fission successfully, meaning that there will be very little U-234 produced in the reactor's thorium/U-233 breeder blanket, and the resulting pure U-233 will be comparatively easy to extract and use for weapons. One proposed solution to this is to mix a small amount of natural or depleted uranium into the thorium breeder blanket. The irradiated material will then be useless for weapons purposes as then the U-233 would require isotopic separation) from the U-238. A small amount of plutonium would be present but will also be low-grade.
Associated reactor types
One design of fast neutron reactor, specifically designed to address the waste disposal and plutonium issues, was the Integral Fast Reactor (a.k.a. Integral Fast Breeder Reactor, although the original reactor was designed to not breed a net surplus of fissile material) [3] [4].
To solve the waste disposal problem, the IFR had an on-site electrowinning fuel reprocessing unit that recycled the uranium and all the transuranics (not just plutonium) via electroplating, leaving just short half-life fission products in the waste. Some of these fission products could later be separated for industrial or medical uses and the rest sent to a waste repository (where they would not have to be stored for anywhere near as long as wastes containing long half-life transuranics). It is thought that it would not be possible to divert fuel from this reactor to make bombs, as several of the transuranics spontaneously fission so rapidly that any assembly would melt before it could be completed. The project was canceled in 1994, at the behest of then-Secretary of Energy Hazel O'Leary.
See also
External links
- US Nuclear Program
- IAEA Fast Reactors Database
- IAEA Technical Documents on Fast Reactors
- Atomic Heritage Foundation - EBR-I
- The Changing Need for a Breeder Reactor by Richard Wilson at The Uranium Institute 24th Annual Symposium, September 1999
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