tailieunhanh - Material Science_ Vol 2 of 2 - US DOE (1993) Episode 8

Tham khảo tài liệu 'material science_ vol 2 of 2 - us doe (1993) episode 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Plant Materials DOE-HDBK-1017 2-93 CLADDING AND REFLECTORS CLADDING AND REFLECTORS Nuclear fuels require surface protection to retain fission products and minimize corrosion. Also pelletized fuel requires a tubular container to hold the pellets in the required physical configuration. The requirements for cladding material to serve these different purposes will vary with the type of reactor however some general characteristics can be noted. This chapter will discuss the general characteristics associated with cladding and reflectors. EO STATE the four major characteristics necessary in a material used for fuel cladding. EO IDENTIFY the four materials suitable for use as fuel cladding material and their applications. EO STATE the purpose of a reflector. EO LIST the five essential requirements for reflector material in a thermal reactor. Cladding Cladding is used to provide surface protection for retaining fission products and minimizing corrosion. Cladding is also used to contain pelletized fuel to provide the required physical configuration. Mechanical properties such as ductility impact strength tensile strength and creep must be adequate for the operating conditions of the reactor core. Ease of fabrication is also important. It is desirable that ordinary fabrication procedures be applicable in fabricating the desired shape. The cladding must have a high corrosion resistance to its operating environment. It must have a high melting temperature to withstand abnormal operating conditions such as high temperature transients. Thermal conductivity should be high to minimize thermal stresses arising from temperature differences and the coefficient of expansion should be low or well-matched with that of other materials. The cladding material should not be susceptible to radiation damage. The nuclear properties of fuel cladding material must also be satisfactory. For thermal reactors it is important that the material have a reasonably small absorption cross