Reactor fast breeder

2- 2xh core consists of suppliers of fast neutrons 233]j or Puel is 

Fast breeder reactors are not operated, as e.g. light-water reactors, with slow neutrons, but with unmoderated fast neutrons as they occur immediately upon nuclear fission. These fast neutrons are necessary to sustain the chain reaction. The neutron yield per fission is here larger, since more neutrons are left over for the breeding process, once the neutrons lost by absorption and leakage have been subtracted. They are absorbed by or which are 

Uranium (ca. 20% is used as the fuel, but mainly with 239pu in the form of a UO2/PUO2 mixture. The breeding blanket consists of depleted uranium from isotope separation plants or from reprocessing plants for spent nuclear fuels. Axially movable boron carbide absorbers are distributed in the fuel zone for shutting down purposes. The uranium utilized can be ca. 100 times better utilized than e.g. in light-water reactors. 

Since with this high uranium utilization less rich uranium deposits (down to the uranium concentration in seawater) also become economically viable, nuclear energy from breeder reactors is a practically inexhaustible energy source. 

Light-water cannot be used as a heat transporting agent, since the fast neutrons may not be slowed down. The preferred heat transferring medium is liquid sodium. 

The amount of U-235 present in a nuclear fuel rod is gradually depleted, and ultimately there is insufficient present for the economic generation of power. A fast-breeder reactor uses the interaction of U-238 with energetic (fast) neutrons to generate the plutonium isotope Pu-239. As Pu-239 can be used as a nuclear fuel, a breeder reactor produces more fuel than it consumes. The sequence of steps is  

Space exploration relies heavily on solar energy when the spacecraft is in the inner solar system. However, solar power is insufficient for spacecraft that have to journey to the outer planets. Chemical energy sources, typically batteries, tend to be relatively heavy and have rather short lifetimes for missions that are to last many years. The solution adopted to date is to combine a radioactive solid with a thermoelectric generator (see Section 15.2.3). The advantages of this solution are that there are no liquids to spill and no moving parts to wear, and a nuclear isotope with a long half-life will continue to provide power over the lifetime of the craft. 

A suitable fuel, used in the Galileo Jupiter explorer, which was finally destroyed in 2003, is the isotope Pu. This is an a-emitter, which provides about 0.5 Wg . The half-life is 87.4 years. The fuel is the solid oxide plutonium dioxide, Pu02. Chemically, it is similar to the uranium dioxide used in thermal reactors, and adopts the same fluorite (Cap2) crystal structure, similar to that of calcia-stabiUsed zirconia and UO2. This structure is inert chemically and stable up to the melting point of approximately 2500 °C. The oxide is pressed and sintered into pellets under conditions that lead to high density and low, but not zero, porosity. This is to ensure dimensional stability of the pellets over the lifetime of the spacecraft because, as Pu is an a-emitter, the resulting helium gas must be allowed to escape. 

The Pu-239 has a half-life of 24 000 years and can be collected for use in fission reactions. The high neutron flux needed is obtained from a reactor using uranium-235 and no moderator. As each decay from the uranium produces more than 2 neutrons it is possible for the reactor to produce more plutonium-239 than it consumes uranium-238. However, the returns are not great, and it would take about 20 breeder reactors running for one year to produce enough plutonium to run a further reactor for one year. 

The fuel in fast-breeder reactors is an oxide, as with a thermal reactor. The material chosen is a solid solution of uranium and plutonium dioxides, U tPU -jC)2. This material shares the same fluorite (Cap2) structure-type as uranium dioxide and plutonium dioxide. 

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Fig. 5. Radioactivity after shutdown per watt of thermal power for A, a Hquid-metal fast breeder reactor, and for a D—T fusion reactor made of various stmctural materials B, HT-9 ferritic steel C, V-15Cr-5Ti vanadium—chromium—titanium alloy and D, siUcon carbide, SiC, showing the million-fold advantage of SiC over steel a day after shutdown. The radioactivity level after shutdown is also given for E, a SiC fusion reactor using the neutron reduced...

Herein reactors are described in their most prominent appHcation, that of electric power. Eive distinctly different reactors, ie, pressurized water reactors, boiling water reactors, heavy water reactors, graphite reactors, and fast breeder reactors, are emphasized. A variety of other appHcations and types of reactors also exist. Whereas space does not permit identification of all of the reactors that have been built over the years, each contributed experience of processes and knowledge about the performance of materials, components, and systems. 

Full advantage of the neutron production by plutonium requires a fast reactor, in which neutrons remain at high energy. Cooling is provided by a hquid metal such as molten sodium or NaK, an alloy of sodium and potassium. The need for pressurization is avoided, but special care is required to prevent leaks that might result in a fire. A commonly used terminology is Hquid-metal fast-breeder reactor (LMFBR). 

As a part of the power demonstration program of the AFC in the 1950s, the Enrico Fermi fast breeder reactor (Fermi-1) was built near Detroit by a consortium of companies led by Detroit Edison. Fermi-1 used enriched uranium as fuel and sodium as coolant, and produced 61 MWe. It suffered a partial fuel melting accident in 1966 as the result of a blockage of core coolant flow by a metal plate. The reactor was repaired but shut down permanently in November 1972 because of lack of binding. Valuable experience was gained from its operation, however (58). 

The United States continued fast-breeder reactor research and development with the building of the fast flux test faciHty (FFTF) at Hanford and the SEFOR reactor in Arkansas (59). The next plaimed step was to build a prototype power reactor, the Clinch River fast-breeder plant (CRFBP), which was to be located near Oak Ridge, Teimessee. 

Fig. 11. Reactor core of MONJU, the Japanese fast-breeder reactor. Courtesy of Power Reactor and Nuclear Fuel Development Corp.

The only other fast-breeder reactors in operation in the world are the 233 MWe Phnnix in France, the 135 MWe BN-350 in Ka2akhstan, and the 560 MWe BN-600 Beloyarskiy in Russia. 

Fast Breeder Reactors" uader "Nuclear Reactors" ia ECT3rd ed., VoL 16, pp. 184—205, by P. Murray, Westiaghouse Electric Corp. 

P. V. Evans, ed.. Fast Breeder Reactors, Proceedings of the London Conference on Past Breeder Reactors of the British Nuclear Energy Society, May... 

At high temperature, sodium and its fused haHdes are mutually soluble (14). The consolute temperatures and corresponding Na mol fractions are given in Table 3. Nitrogen is soluble in Hquid sodium to a limited extent, but sodium has been reported as a nitrogen-transfer medium in fast-breeder reactors (5) (see Nuclearreactors). 

Properties. Most of the alloys developed to date were intended for service as fuel cladding and other stmctural components in hquid-metal-cooled fast-breeder reactors. AHoy selection was based primarily on the following criteria corrosion resistance in Hquid metals, including lithium, sodium, and NaK, and a mixture of sodium and potassium strength ductihty, including fabricabihty and neutron considerations, including low absorption of fast neutrons as well as irradiation embrittlement and dimensional-variation effects. Alloys of greatest interest include V 80, Cr 15, Ti 5... 

When a fast-breeder reactor is shut down quickly, the temperature of the surface of a number of components drops from 600°C to 400°C in less than a second. These components are made of a stainless steel, and have a thick section, the bulk of which remains at the higher temperature for several seconds. The low-cycle fatigue life of the steel is described by... 

The CREDO data base contains data from The Fast Flux Test Facility in Richland, Washington, The Experimental Breeder Reactor - II in Idaho Falls, Idaho, The test loops of the Energy Technology Engineering Center (ETEC) in Canoga Park, California, The JOYO Liquid Metal Fast Breeder Reactor at the 0-Arai Engineering Center (OEC) in Japan, and the test loops of OEC. 

LMFBR Liquid Metal Fast Breeder Reactor... 

Many of the fission products formed in a nuclear reactor are themselves strong neutron absorbers (i.e. poisons ) and so will stop the chain reaction before all the (and Pu which has also been formed) has been consumed. If this wastage is to be avoided the irradiated fuel elements must be removed periodically and the fission products separated from the remaining uranium and the plutonijjm. Such reprocessing is of course inherent in the operation of fast-breeder reactors, but whether or not it is used for thermal reactors depends on economic and political factors. Reprocessing is currently undertaken in the UK, France and Russia but is not considered to be economic in the USA. 

Hafele, W. Holdren, J. P. Kessler, G. and Knlciiiski, G. L. (1977). Fusion and Fast Breeder Reactors. Laxeiiburg, Austria International Institute for Applied Systems Analysis. 

Several alternative technologies that were heavily supported failed to become commercially viable. The most obvious case was the fast breeder reactor. Such reactors are designed to produce more fissionable material from nonfissionable uranium than is consumed. The effort was justified by fears of uranium exhaustion made moot by massive discoveries in Australia and Canada. Prior to these discoveries extensive programs to develop breeder reactors were government-supported. In addition, several different conventional reactor technologies were aided. The main ongoing nuclear effort is research to develop a means to effect controlled fusion of atoms. 

Other newer designs include the advanced, gas-cooled reactor (AGR), Canadian deuterium reactor (CANDUR), sodium-cooled reactor (SCR), sodium-heated reactor (SHR), and fast breeder reactor (FBR). These reactors employ either natural or enriched uranium fuels that may be modified in some way (e.g., graphite-moderated fuels). 

Many of the techniques available to purify alkali metals were initially developed to use with liquid sodium as a consequence of its large-scale application in liquid-metal-cooled fast-breeder reactors. These techniques can be summarized as filtration or cold trapping distillation or chemical (gettering). 

The phrase "nuclear power" covers a number of technologies for producing electric power other than by burning a fossil fuel. Nuclear fission in pressurized water-moderated reactors—light water reactors— represents the enrrent teehnology for nuclear power. Down the line are fast breeder reactors. On the distant horizon is nnclear fusion. 

Sodium superheat experiments were performed in a forced-convection facility employing system parameters in the range of interest for application to loop- and pot-type liquid metal-cooled fast breeder reactors (LMFBRs). The test section was... 

For very long, helically coiled steam generator tubes, and for conditions typical of liquid-metal fast breeder reactors (LMFBRs), where steam is generated on the tube side, an overall heat transfer correlation for the whole boiling length (from X = 0 to X = 1.0) has been deduced experimentally (Campolunghi et al., 1977b) ... 

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