Sodium liquid

Sodium chloride has a density, D, of 2.168 gem-3(at 0 °C), which depends on temperature according to Eq. (9), where t 

The dependence of other relevant properties upon temperature is summarized in Tables 27-29. 

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Liquid sodium alumiaate is available ia steel drums having an approximate capacity of 210 L and bulk shipments are available ia either tank tmcks or railroad tank cars. The density of Hquid sodium alumiaate is usually from 1450 to 1510 kg/m. SoHd products are available ia moisture-proof paper bags or fiber drums containing approximately 23 and 150 kg, respectively. 

Sodium is a soft, malleable soHd readily cut with a knife or extmded as wire. It is commonly coated with a layer of white sodium monoxide, carbonate, or hydroxide, depending on the degree and kind of atmospheric exposure. In a strictiy anhydrous iaert atmosphere, the freshly cut surface has a faintiy pink, bright metallic luster. Liquid sodium ia such an atmosphere looks much like mercury. Both Hquid and soHd oxidize ia air, but traces of moisture appear to be required for the reaction to proceed. Oxidation of the Hquid is accelerated by an iacrease ia temperature, or by iacreased velocity of sodium through an air or oxygen environment. 

High Surface Sodium. Liquid sodium readily wets many soHd surfaces. This property may be used to provide a highly reactive form of sodium without contamination by hydrocarbons. Powdered soHds having a high surface area per unit volume, eg, completely dehydrated activated alumina powder, provide a suitable base for high surface sodium. Other powders, eg, sodium chloride, hydride, monoxide, or carbonate, can also be used. 

Figure 12.1 The solubilities of liquid sodium in the liquid sodium halides...

Sodium, potassium and sodium-potassium alloys Liquid sodium, potassium or alloys of these elements have little effect on niobium at temperatures up to 1 000°but oxygen contamination of sodium causes an increase in corrosionSodium does not alloy with niobium . In mass transfer tests, niobium exposed to sodium at 600°C exhibited a corrosion rate of approximately 1 mgcm d . However, in hot trapped sodium at 550°C no change of any kind was observed after 1 070 h . 

Nuclear Niobium finds use in some nuclear reactors on account of its compatibility with uranium and liquid sodium/potassium at fast reactor temperatures. 

It is in its behaviour to caustic alkalis that zirconium shows itself to be superior to those other elements of Groups IV and V whose resistance to corrosion results primarily from an ability to form surface films. Thus, in contrast to tantalum, niobium and titanium, zirconium is virtually completely resistant to concentrated caustic solutions at high temperatures, and it is only slightly attacked in fused alkalis. Resistance to liquid sodium is good. Zirconium is thus an excellent material of construction for sections of chemical plant demanding alternate contact with hot strong acids and hot strong alkalis—a unique and valuable attribute. 

The equilibrium levels of the reaction products are very small, but both can dissolve in liquid sodium, and sodium oxide can form compounds with silica. As a consequence, the reaction moves to the right, leading to further reduction of silica. Nevertheless, vitreous silica crucibles have been used sucessfully for containing molten antimony (850°C), copper (1 210°C), gallium (1 100°C), germanium (1 100°C), lead (500°C) and tin (900 C). 

Borgstedt and Freeshave shown that for the corrosion of both stabilised and unstabilised austenitic stainless steels in flowing liquid sodium at 700°C there is an almost linear dependence of the corrosion constant, k, on the oxygen content of the sodium, as follows ... 

The effect of carbon on the corrosion of stainless steels in liquid sodium depends upon the test conditions and the composition of the steels . Stabilised stainless steels tend to pick up carbon from sodium, leading to a degree of carburisation which corresponds to the carbon activity in the liquid metal. Conversely, unstabilised stainless steels suffer slight decarburisation when exposed to very pure sodium. The decarburisation may promote corrosion in the surface region of the material and, under creep rupture conditions, can lead to cavity formation at the grain boundaries and decreased strength. 

Loop Tests Loop test installations vary widely in size and complexity, but they may be divided into two major categories (c) thermal-convection loops and (b) forced-convection loops. In both types, the liquid medium flows through a continuous loop or harp mounted vertically, one leg being heated whilst the other is cooled to maintain a constant temperature across the system. In the former type, flow is induced by thermal convection, and the flow rate is dependent on the relative heights of the heated and cooled sections, on the temperature gradient and on the physical properties of the liquid. The principle of the thermal convective loop is illustrated in Fig. 19.26. This method was used by De Van and Sessions to study mass transfer of niobium-based alloys in flowing lithium, and by De Van and Jansen to determine the transport rates of nitrogen and carbon between vanadium alloys and stainless steels in liquid sodium. 

Because sodium, which is liquid between about 100°C and 881°C, has excellent properties as a heat-transfer medium, with a viscosity comparable with that of water and superior heat conductivity , much attention has been paid to liquid sodium corrosion testing of metal and alloys. Indeed, ASTM have issued a Standard Practice which can be used for determination... 

RDT Standard C8-5T, Electrochemical Oxygen Meter for Service in Liquid Sodium, RDT Standards Office, Oak Ridge National Laboratory, Tennessee Pillai, S. R. and Mathews, C. K., J. Nucl. Mater., 137, 107 (1986)... 

Test method for determining the susceptibility to intergranular corrosion of 5XXX series aluminium alloys by mass loss after exposure to nitric acid (NAMLT test) Practice for liquid sodium corrosion testing of metals and alloys... 

Because of its excellent heat conductivity, liquid sodium has been proposed as a cooling liquid for use in nuclear power plants. 

The chlorine used to purify your drinking water was possibly made by electrolyzing molten Nad to produce liquid sodium and gaseous chlorine. 

Tables 23-26 show the variation with temperature of some relevant physical properties of liquid sodium.

Table 25. Enthalpy, H -H0, and heat capacity, Cp, of liquid sodium...

Typically, either liquid sodium salts of 60 °Be are employed (18% Na20, 36% Si02) or alternatively, potassium salts of 40.75 °Be (12.6% K20, 26.8% Si02). 

Iodine was determined by an iodometric titration adapted from White and Secor.(3) Instead of the normal Carius combustion, iodide was separated from the samples either by slurrying in 6M NaOH, or by stirring the sample with liquid sodium-potassium (NaK) alloy, followed by dissolving excess NaK in ethanol. Precipitated plutonium hydroxides were filtered. Iodine was determined in the filtrate by bromine oxidation to iodate in an acetate buffer solution, destruction of the excess bromine with formic acid, acidifying with SO, addition of excess KI solution, and titrating the liberated iodine with standard sodium thiosulfate. The precision of the iodine determination is estimated to be about 5% of the measured value, principally due to incomplete extraction of iodine from the sample. 

Special correlations have also been developed for liquid metals, used in recent years in the nuclear industry with the aim of reducing the volume of fluid in the heat transfer circuits. Such fluids have high thermal conductivities, though in terms of heat capacity per unit volume, liquid sodium, for example, which finds relatively widespread application, has a value of Cpp of only 1275 k.l/ni1 K. 

Many of the techniques available to purify alkali metals were initially developed to use with liquid sodium as a consequence of its large-scale application in liquid-metal-cooled fast-breeder reactors. These techniques can be summarized as filtration or cold trapping distillation or chemical (gettering). 

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