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Zirconium nuclear grades

Table 5.20 Minimum mechanical properties of nuclear grade zirconium alloys... Table 5.20 Minimum mechanical properties of nuclear grade zirconium alloys...
The pyrochemical process of zirconium-hafnium separation is particularly attractive not only because it makes the entire process of nuclear-grade zirconium metal production from zircon more economical than that involving a hydrometallurgical separation stage, but also... [Pg.411]

Hafnium is obtained as a by-product of the production of hafnium-free nuclear-grade zirconium (see Nuclear reactors ZlRCONlUMAND zirconium compounds). Hafnium s primary use is as a minor strengthening agent in high temperature nickel-base superalloys. Additionally, hafnium is used as a neutron-absorber material, primarily in the form of control rods in nuclear reactors. [Pg.439]

Hafnium is usually present to the extent of 1 or 2 per cent in view of its close chemical similarity with zirconium, but separation procedures are available if nuclear grade zirconium is required free from this element. [Pg.288]

Commercial-grade zirconium contains from 1 to 3% hafnium. Zirconium has a low absorption cross section for neutrons, and is therefore used for nuclear energy applications, such as for... [Pg.55]

Reactor-grade zirconium is essentially free of hafnium. Zircaloy(R) is an important alloy developed specifically for nuclear applications. Zirconium is exceptionally resistant to corrosion by many common acids and alkalis, by sea water, and by other agents. Alloyed with zinc, zirconium becomes magnetic at temperatures below 35oK. [Pg.56]

The zirconium alloys with the ASTM specifications are given in Table 4.85. The composition of nuclear-grade alloys is given in Table 4.86. The composition of other alloys developed for nuclear applications is given in Table 4.87. [Pg.291]

In recent years progress has been made in the manufacture of zirconium by electrolysis such that satisfactory nuclear grade metal can be produced. The economies of the process probably allow large scale production at a similar cost to the rival Kroll type reduction process. [Pg.286]

Table 4.67. Nuclear grades of zirconium (i.e., hafnium free)... Table 4.67. Nuclear grades of zirconium (i.e., hafnium free)...
One of the major differences between nuclear and nonnuclear zirconium alloys is in their hafnium content. Nuclear grades of zirconium alloys are virtually free of hafnium (not greater than 100 ppm). Nonnuclear grades of... [Pg.573]

As it occurs in nature, zirconium is always found in association with hafnium, in the ratio of 1 part hafnium to 50 parts zirconium, and commercial-grade zirconium contains approximately 2% hafiiium. Because hafnium has a high absorption capacity for thermal neutrons, nuclear reactor-grade zirconium is not permitted to contain more than 0.025% Hf, and usually it contains closer to 0.01%. [Pg.769]

The production of sihcon tetrachloride by these methods was abandoned worldwide in the early 1980s. Industrial tetrachlorosilane derives from two processes associated with trichlorosilane, the direct reaction of hydrogen chloride on sihcon primarily produced as an intermediate for fumed sihca production, and as a by-product in the disproportionation reaction of trichlorosilane to silane utilized in microelectronics. Substantial quantities of tetrachlorosilane are produced as a by-product in the production of zirconium tetrachloride, but this source has decreased in the 1990s owing to reduction in demand for zirconium in nuclear facihties (see Nuclearreactors). The price of tetrachlorosilane varies between l/kg and 25/kg, depending on grade and container. [Pg.32]

The Kroll process for tire reduction of tire halides of refractory metals by magnesium is exemplified by the reduction of zirconium tetrachloride to produce an impure metal which is subsequently refined with the van Arkel process to produce metal of nuclear reactor grade. After the chlorination of the impure oxide in the presence of carbon... [Pg.345]

Uranium Dioxide Production. The majority of the world s nuclear reactors are fueled with slightly enriched UOg prepared in the form of dense sintered pellets that are encapsulated in small bore tubes of zirconium alloy or stainless steel. Hex at the required enrichment(s) is produced specifically for a given reactor charge and the first process step with the UFg is to convert it to UOg having the desired ceramic-grade quality. This means an oxide which after granulation and pelleting can be sintered quickly and uniformly to pellets of near stoichiometric density. [Pg.344]

This industry has most of the corrosion problems of other industries and some that are all of its own. Right from the start, the potential for disaster was recognized and tackled by using high-grade materials in many parts of the systems. Zirconium alloys were needed, which had their own corrosion problems and solutions. Growing worldwide demands for acceptable environmental performance have alienated others to the cause of nuclear power, in particular, after events at Three Mile Island and Chernobyl. [Pg.392]

For hafnium. Grade R1 materials, which are low in zirconium content, are for nuclear applications, and Grade R3 materials, which may contain a higher zirconium content, are intended for nonnuclear applications. [Pg.613]

Zirconium ores contain a few percent of its sister element, hafnium. Hafnium has chemical and metallurgical properties similar to those of zirconium, although their nuclear properties are markedly different. Flafnium is a neutron absorber but zirconium is not. As a result, there are nuclear and nonnudear grades of zirconium and zirconium alloys. Some commerdally available grades of zirconium and its alloys are listed in Table 22.2. [Pg.574]

The presence of hafnium in zirconium does not significantly influence mechanical properties other than the thermal neutron cross-section. Moreover, hafniiun is a valuable metal for many applications. The source of hafnium comes as the byproduct in the production of zirconium. The nonnudear grades of zirconium alloys are also low in hafnium content. Consequently, the coimterparts of nuclear and normuclear grades of zirconium alloys are interchangeable in mechanical properties. However, specification requirements for nuclear materials are more extensive than those for nonnuclear materials. Only requirements for nonnuclear materials are given in Table 22.3 and Table 22.4. It can be seen that Zr 705 is the... [Pg.574]

Most zirconium is used as an oxide in commercial applications. Only a few percent is converted to the metal and used in chemical process industries because of its excellent corrosion resistance, while a special grade of zirconium is used in the nuclear industry. There are no official statistics for the production and consumption of zirconium metal. The annual global production capacity is estimated approximately at 85001, and total production/consumption is about 7000 t/year. The main applications of zirconium metal are for the nuclear energy and chemical process industries. About 85% of zirconium metal, 5000-6000 t/year, is used in the nuclear industry. Commercial-quality zirconium still contains 1 -3% hafnium. This contaminant is unimportant except in nuclear applications. For nuclear reactor materials, the zirconium metal should have a very low hafnium content of less than 0.01 wt%. Most Zr metal is produced by the reduction of the zirconium (ZrCy chloride with magnesium metal in the Kroll process. [Pg.391]


See other pages where Zirconium nuclear grades is mentioned: [Pg.959]    [Pg.335]    [Pg.959]    [Pg.335]    [Pg.443]    [Pg.318]    [Pg.2]    [Pg.692]    [Pg.684]    [Pg.151]    [Pg.732]    [Pg.613]    [Pg.671]    [Pg.468]    [Pg.766]    [Pg.738]    [Pg.730]    [Pg.777]    [Pg.764]    [Pg.684]    [Pg.883]    [Pg.2]    [Pg.218]    [Pg.326]    [Pg.330]    [Pg.916]   
See also in sourсe #XX -- [ Pg.288 ]




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