High-temperature reactor

Nuclear Applications. Use of the nitrides of uranium-235 and thorium as fuels and breeders in high temperature reactors has been proposed (see Nuclearreactors). However, the compounds most frequently used for this purpose are the oxides and carbides. Nitrides could be useful in high... 

Aircraft Reactors. As early as World War II, the U.S. Army Air Force considered the use of a nuclear reactor for the propulsion of aircraft (62—64). In 1946 the nuclear energy for propulsion of aircraft (NEPA) program was set up at Oak Ridge, under Fairchild Engine and Airplane Corporation. Basic theoretical and experimental studies were carried out. The emphasis was on materials. A high temperature reactor was built and operated successfiiUy. 

The Tj-carbides are not specifically synthesized, but are of technical importance, occurring in alloy steels, stelUtes, or as embrittling phases in cemented carbides. Other complex carbides in the form of precipitates may form in multicomponent alloys or in high temperature reactor fuels by reaction between the fission products and the moderator graphite, ie, pyrographite-coated fuel kernels. 

The Arbeitsgemeinschaft Versuchsreaktor (AVR) and Thorium High-Temperature Reactor (THTR-300) were both helium-cooled reactors of the pebble-bed design [29,42,43]. The major design parameters of the AVR and THTR are shown in Table 10. Construction started on the AVR in 1961 and full power operation at 15MW(e) commenced in May 1967. The core of the AVR consisted of approximately 100,000 spherical pebble type fuel elements (see Section 5). The pebble bed was surrounded by a cylindrical graphite reflector and structural carbon... 

Control of the nuclear chain reaction in a reactor is maintained by the insertion of rods containing neutron absorbing materials such as boron, boron carbide, or borated steel. In state-of-the-art high temperature reactor designs, such as the Gas... 

Haag, G., Kugeler, K. and Philippen, P.-W., The high temperature reactor (HTR) and the new German safety concept for future nuclear power plants. In Proceedings of the... 

The creep strength of steels is a factor limiting the maximum temperatures for such high-pressure equipment as shells and stirrers of high temperature reactors. Table 3.10 presents creep data for temperatures ranging from 400 to 600°C. The stress for 1% creep in 100,000 hours (which is a design criterion) is accepted to be not less than two-thirds of the creep stresses. 

In contrast, the high-temperature reactor operates at -350 °C and 25 bar, using a gas-fluidized bed reactor of either the circulating or the normal type. The high-tem-perature process is mainly used to produce gasoline and chemicals, such as alpha olefins, and the low temperature process to produce waxes. 

Waste-heat boilers are often used to recover heat from furnace flue gases and the process gas streams from high-temperature reactors. The pressure, and superheat temperature, of the stream generated will depend on the temperature of the hot stream and the approach temperature permissible at the boiler exit (see Chapter 12). As with any heat-transfer equipment, the area required will increase as the mean temperature driving force (log mean AT) is reduced. The permissible exit temperature may also be limited by process considerations. If the gas stream contains water vapour and soluble corrosive gases, such as HC1 or S02, the exit gases temperature must be kept above the dew point. 

Refractory bricks and cements are needed for equipment operating at high temperatures such as, fired heaters, high-temperature reactors and boilers. 

Hydrogen Production with Very High-Temperature Reactor.147... 

Hydrogen Production with Very High-Temperature Reactor 4.4.1 Overview of the Very High-Temperature Reactor... 

National programs are underway to develop and deploy the reactor and applications in China, France, South Korea, and United States [35-38]. Many more countries are participating in R D through the High Temperature Reactor Technology Network of the European Union [39] and the GIF including the 10 member countries [40]. Builds of full-scale commercial demonstration reactors are actively planned in several countries such as South Africa [41] and the United States [38]. 

Hittner, D., The European programme of development of HTR/VHTR technology, in Proc. of the 2nd International Topical Meeting on High Temperature Reactor Technology, Beijing, September 22-24,2004. 

Hcit, W., Huschka, H, Rind, W., and Kaiser, G.G., Status of qualification of high-temperature reactor fuel element spheres, Nuclear Technology, 1985, 69, 44 54. 

This event tree analysis shows that a dangerous runaway reaction will occur on average 0.025 time per year, or once every 40 years. This is considered too high for this installation. A possible solution is the inclusion of a high-temperature reactor shutdown system. This control... 

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