Heat transfer components, nuclear

To slow down and control the rate of reaction, a moderator is also required. Typically, the moderator is boric acid, graphite, or heavy water (D20) and is present in the high-purity water, which also serves as a primary coolant for the fuel and the reactor vessel. The tremendous heat generated by nuclear fission is transferred to this closed-loop coolant, which is contained within a reactor primary-coolant circulation system. The high-purity water coolant also contains a suitable pH buffer such as lithium hydroxide, which has the additional effect of limiting the corrosion of fuel-cladding and other components. 

Flow instabilities are undesirable in boiling, condensing, and other two-phase flow processes for several reasons. Sustained flow oscillations may cause forced mechanical vibration of components or system control problems. Flow oscillations affect the local heat transfer characteristics and may induce boiling crisis (see Sec. 5.4.8). Flow stability becomes of particular importance in water-cooled and watermoderated nuclear reactors and steam generators. It can disturb control systems, or cause mechanical damage. Thus, the designer of such equipment must be able to predict the threshold of flow instability in order to design around it or compensate for it. 

Grolmes, M. A., and H. K. Fauske, 1969, Propagation Characteristics of Compression and Rarefaction Pressure Pulses in One-Component Vapor-Liquid Mixtures, Nuclear Eng. Design 77 137-142. (3) Grolmes, M. A., and H. K. Fauske, 1970, Modeling of Sodium Expulsion of Freon-11, ASME Paper 70-HT-24, Fluids Engineering Heat Transfer and Lubrication Conf., Detroit, MI. (4)... 

A fission reactor contains three components nuclear fuel rods, control rods, and a liquid (usually water) to transfer the heat created by fission from the reactor to the turbine. The nuclear fuel is primarily uranium-238 plus about 3 percent uranium-235. Because the uranium-235 atoms are so highly diluted with... 

OTHER COMMENTS terphenyls are important industrially as chemical intermediates in the manufacture of nonspreading lubricants, as heat transfer fluids, and as nuclear reactor coolants are also used as constituents of waxes and polishes, and as plasticizers for resin-bodied paints para-terphenyl has been used as a component of sunscreen lotion the terphenyls are considered a non-significant industrial hazard due to their low vapor pressure. 

The Prototype Plant Nuclear Process Heat (PNP) project was founded in 1972 with the goals of developing HTGRs for high gas outlet temperatures of 950 °C as a source of process heat to test components for heat transfer to the process plant, and to demonstrate processes and experimental facilities for coal gasification. The technical feasibility of a nuclear process heat reactor for the refinement of coal has been established, main components developed, and its basic licensing capability confirmed. Studies on the technical feasibility and economic competitiveness of the processes for nuclear coal refinement were completed in 1987. 

The goal of the conduction heat transfer is to determine the temperature field in a medium (such as fuel rod) and the rate of heat transfer to and from the medium. Typically, the media is subjected to nonimiform temperature distribution which is a result of either a heat source within the medium or heat flux from the boundary of the medium. In this section various forms of the heat conduction equation that govern the temperature field in a medium and its associated boimdary conditions are given. Some examples of the heat conduction in nuclear fuel rod and other components are presented. 

The reference thermal power conversion system consists of the heat transfer geometry surrounding the nuclear core cladding and the closed Biayton cycle components that convert the thermal power generated by the reactor into electrical power. A schematic drawing of the closed Biayton cycle system appears as Fig. 5.19, where the heat sink is the air-source heat exchanger, and the heat source is the reactor. 

The deviations from standard practice required to adapt the various components to the molten-salt system are discussed below. The schematic diagram of a molten-sitlt heat-transfer. system presented in Hg. 15-1 indicates th< relative positions of the various components. For nuclear operation, an off-gas system is supplied, as described in Chapter 17. The vapor conden.siUion trap indicated in Fig. 15-1 is required only on systems that contain ZrF4 or a comparably volatile fluoride as a component of the molten salt. 

The connection scheme developed by the European Projects HYTHEC and RAPHAEL (Le Duigou, 2007) represents a self-sustainable plant concept in which, in addition to the heat supply to the S-I cycle, the electrical demand of the internal consumers is provided by the nuclear reactor. The high temperature flow exiting the nuclear reactor transfers its heat via an IHX to a secondary loop which interacts with the components of the S-I cycle components. The high temperature heat flow is split and partially directed to the chemical part of the cycle and another part to a Brayton cycle for electricity production needed to power pumps, compressors, heat pumps and other auxiliaries. 

PER F. PETERSON is a professor in the Department of Nuclear Engineering at the University of California, Berkeley, where he teaches and conducts research in heat and mass transfer, multi-phase/multi-component flows, thermal hydraulics, and nuclear materials management. He is also chair of the Energy Resources Group, an interdisciphnary academic unit of U.C., Berkeley with programs that treat issues of energy, resources, development and international security as... 

The basic components of the nuclear power unit are as follows the reactor, the system of power conversion, the system of power transfer (the coolant loop), the system of heat removal into the environment, and the unit of radiation protection. 

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