Tham khảo tài liệu 'lubrication fundamentals 2011 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Figure Rotary closing valve. Greases used in grease-lubricated bearings require good water resistance and rust protection. They should be suitable for use in centralized lubrication systems and should have good pumpability at the lowest water temperatures. Both lithium and calcium soap grease are used. NLGI no. 2 consistency greases are usually used but in some extremely cold locations NLGI no. 1 consistency greases are selected. Compressors used in hydroelectric plants can be lubricated as outlined in Chapter 17. Copyright 2001 by Exxon Mobil Corporation. All Rights Reserved. 14 Nuclear Reactors and Power Generation Nuclear reactors fall into the following categories zero-power research reactors test reactors special isotope production reactors and power reactors. Basically all nuclear reactors are similar in that they all utilize the fission chain reaction process to provide heat energy through the splitting fission of the heavy nuclei of fissionable materials. This reaction produces about 1 X 108 times the energy release of burning 1 carbon atom of fossil fuel plus the production of extra neutrons needed to sustain the chain reaction. The fuel used is generally 235U uranium-235 233U uranium-233 or 239Pu plutonium-239 . This chapter provides general information on reactors with emphasis on those used in power generation. I. REACTOR TYPES The power reactor whose main function is to furnish energy consists broadly of a core containing nuclear fuel a moderator although this is eliminated in fast neutron reactors a cooling system a control system and shielding. In practice it is possible to design an almost endless number of different but basically similar reactor types by using various combinations of fuel coolant and moderator. It would seem that such a variety could lead to confusion but in actuality certain combinations are ruled out by unavailability of some of the components or by economics. For example many areas must use natural uranium because of the .
