Reactor fluid-fueled reactors

A third possibility is that fluid fuel reactors, such as the ORNL aqueous reactor, or the BNL liquid metal reactor, will supply some fraction of our future nuclear economy. These reactors are usually designed as completely self-contained systems including continuous reprocessing of fuel. 

The processes associated with fluid fuel reactors are too varied to be considered in detail here. The reader is referred to references (FI) and (D3) for further information. 

A great deal of knowledge has been gained about the behavior of fission products in fluoride salts from the experience with fluid-fueled reactors. This evidence has been gleaned from numerous irradiation... 

All equations have been specialized to the case of the fluid fuel reactor, without internal structure. The generalization is usually obvious. 

Several fluid-fueled reactors have been built and operated as experiments. The concept is that fuel is contained within the coolant. Systems of this type include aqueous fuel systems, liquid metal-fueled systems, molten salt systems, and gaseous suspension systems. The homogeneous reactor experiment was constructed and operated at Oak Ridge Nahonal Laboratory, as was the Molten-Salt Reactor experiment. A liquid metal fuel reactor experiment was operated at Brookhaven National Laboratory. Power reactors of this type have not been built. 

Selection of the salt composition strongly depends on the specific design application fluid (burner or breeder) or solid fuel, primary or secondary coolant and heat transport fluid, etc. In choosing a fuel salt for a given fluid fuel reactor design the following... 

Fluid Fueled Reactors. These concepts include the Molten Salt Reactor, the Molten Chloride Reactor, and aqueous solutions. Online refueling allows high capacity factors and low source terms. Online processing reduces fission product inventory. However, the possibility of selective removal of an essentially pure fissile stream during online reprocessing is a concern. These concepts can have strong negative temperature coefficients of reactivity... 

Secondary systems. Boiler water. Chemical treatment of the water in the steam side of a fluid fuel reactor heat exchanger is a major... 

Introduction. In 1950 the Oak Ridge National Laboratory undertook the task of designing, building, and operating a pilot-plant fluid-fuel reactor, the Homogeneous Reactor Experiment (HRE-1), shown in... 

The search for a liquid for use at high temperatures and low pressures in a fluid-fueled reactor led to the choice of either fluorides or chlorides because of the requirements of radiation stability and solubility of appreciable quantities of uranium and thorium. The chlorides (based on the isotope) are most suitable for fast reactor use, but the low thermal-neutron absorption cross section of fluorine makes the fluorides a uniquely desirable choice for a high-temperature fluid-fueled reactor in the thermal or epithermal neutron region. 

The ability of certain molten salts to dissolve uranium and thorium, salts in quantities of reactor interest made possible the consideration of fluid-fueled reactors with thorium in the fuel, without the danger of nuclear accidents as a result of the settling of a slurry. This additional degree of freedom has been exploited in the study of molten-salt reactors. 

Thermochemical Liquefaction. Most of the research done since 1970 on the direct thermochemical Hquefaction of biomass has been concentrated on the use of various pyrolytic techniques for the production of Hquid fuels and fuel components (96,112,125,166,167). Some of the techniques investigated are entrained-flow pyrolysis, vacuum pyrolysis, rapid and flash pyrolysis, ultrafast pyrolysis in vortex reactors, fluid-bed pyrolysis, low temperature pyrolysis at long reaction times, and updraft fixed-bed pyrolysis. Other research has been done to develop low cost, upgrading methods to convert the complex mixtures formed on pyrolysis of biomass to high quaHty transportation fuels, and to study Hquefaction at high pressures via solvolysis, steam—water treatment, catalytic hydrotreatment, and noncatalytic and catalytic treatment in aqueous systems. 

Manufacture. Titanium chloride is manufactured by the chlorination of titanium compounds (1,134—138). The feedstocks usually used are mineral or synthetic mtile, beneficiated ilmenite, and leucoxenes. Because these are all oxygen-containing, it is necessary to add carbon as well as coke from either coal or fuel oil during chlorination to act as a reducing agent. The reaction is normally carried out as a continuous process in a fluid-bed reactor (139). The bed consists of a mixture of the feedstock and coke. These are fluidized by a stream of chlorine iatroduced at the base (see Fluidization). The amount of heat generated in the chlorination process depends on the relative proportions of CO2 or CO that are formed (eqs. 1 and 2), and the mechanism that... 

SASOLII a.ndIII. Two additional plants weie built and aie in operation in South Africa near Secunda. The combined annual coal consumption for SASOL II, commissioned in 1980, and SASOL III, in 1983, is 25 x 10 t, and these plants together produce approximately 1.3 x lO" m (80,000 barrels) per day of transportation fuels. A block flow diagram for these processes is shown in Figure 15. The product distribution for SASOL II and III is much narrower in comparison to SASOL I. The later plants use only fluid-bed reactor technology, and extensive use of secondary catalytic processing of intermediates (alkylation, polymerisation, etc) is practiced to maximise the production of transportation fuels. 

It is likely that future commercialization of Methanol-to-Olefins (MTO) will take place in a fluid-bed reactor for many of the same reasons which encouraged fluid-bed MTG development, including better temperature control and constant product composition. The olefins produced by this process can be readily converted to gasoline, distillate and/or aviation fuels by commercially available technologies such as Mobil s MOGD process. 

Lappas AA, Samolada MC, Iatridis DK, Voutetakis SS, Yasalos IA. Biomass pyrolysis in a circulating fluid bed reactor for the production of fuels and chemicals. Fuel. 2002 81 2087-95. 

For the production of gasoline and other fuels by catalytic cracking of oils, a fluid bed reactor is used. This is a hybrid of a fixed bed and slurry phase reactor. The catalyst is fluidized as it interacts with the feed to be processed. This application is so important it... 

Molten salt-cooled reactor (MSR), with a fluid fuel and an indirect power cycle. 

The Fischer-Tropsch process has several variants one of which (a high temperature process) produces significant volumes of olefins. This particular variant, known as the Synthol Process, is used to produce fuels from both coal and natural gas in South Africa. A recent development of this process (The Sasol High Temperature Process ) has replaced the original entrained-bed reactors with fluid-bed reactors. The product breakdown is shown in Table 11.3. 

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