Zirconium removal from

Hulls Handling. After the fuel has been dissolved, the residual pieces of zirconium cladding, referred to as hulls, are rinsed and removed from the dissolver vessel. The decay of activation products provides sufficient heat to ensure drying of the hulls and preclude hydrogen formation caused by the radiolysis of water. 

The fifth component is the stmcture, a material selected for weak absorption for neutrons, and having adequate strength and resistance to corrosion. In thermal reactors, uranium oxide pellets are held and supported by metal tubes, called the cladding. The cladding is composed of zirconium, in the form of an alloy called Zircaloy. Some early reactors used aluminum fast reactors use stainless steel. Additional hardware is required to hold the bundles of fuel rods within a fuel assembly and to support the assembhes that are inserted and removed from the reactor core. Stainless steel is commonly used for such hardware. If the reactor is operated at high temperature and pressure, a thick-walled steel reactor vessel is needed. 

Sulfates. Sulfate ions strongly complex zirconium, removing hydroxyl groups and forming anionic complexes. With increasing acidity, all hydroxyl groups are replaced zirconium sulfate [7446-31-3] Zr(S04)2-4H20, with an orthorhombic stmcture (206), can be crystallized from a 45% sulfuric acid solution. Zirconium sulfate forms various hydrates, and 13 different crystalline Zr(S0 2 5 2 [14644-61-2] systems are described in Reference 207. 

When ion-exchange resin containing zirconium hydroxide comes into contact with acidic brine in the RNDS , zirconium hydroxide adsorbs bisulphate ions thus sulphate is removed from brine. For regeneration of the ion-exchange resin, a basic solution is supplied and when it comes into contact with the resin, sulphate desorption starts. 

In order to remove effectively iodide by RNDS , oxidation of iodide to iodate or periodate is necessary. Iodide is oxidised to iodate with excess chlorine. Through contact of dechlorinated brine with the ion-exchange resin containing zirconium hydroxide, the iodide is therefore removed from the brine. 

Uranium stripping Dilute HNO3 solutions at 45-50°C are used to remove uranium from the TBP phase. Traces of the fission products ruthenium and zirconium are eliminated in the second and third cycles of the Purex process. Also, in the second and third cycles, neptunium and the last traces of plutonium are removed from the uranium product. 

Zirconium can be removed from the mixed precipitated acids by fusing them with potassium carbonate and extracting the melt with cold water. The niobium and tantalum pass into solution as niobate and tantalate of potassium respectively, while the zirconium remains undissolved as the dioxide, Zr02.4 The method is more suited for the removal of zirconium from niobates than from tantalates.3... 

Hexachloroethane, removal from zirconium (IV) chloride, 4 124 Hexachloroplumbic(IV) acid, 1 48 Hexaguanidonium tetraphosphate 1-hydrate, 5 97, 100 Hexahalogenoplumbic acids, 1 48 Hexahalogenotellurates(IV), 2 188 Hexaiodostannates(IV), formation of, by tin(IV) iodide, 4 121 Hexametaphosphates (see Metaphosphates)... 

Two impurities are apparent in the product, iron (III) chloride and hexachloroethane. Both are more volatile than zirconium tetrachloride. Nevertheless, if both are to be removed from the product, considerable product inevitably sublimes beyond K. The amount of hexachloroethane impurity is roughly a function of temperature, since runs made at 450° yield virtually none, whereas if the furnace is allowed to go much above 500°, appreciable quantities are formed. The amount of iron (III) chloride impurity depends on the purity of starting materials. ... 

The reverse reaction is also of interest and may occur on metals like zirconium and magnesium. Carbon monoxide will be removed from the system by zirconium at pressures of 10-10 atm., forming metal oxide and carbon. This reaction is also affected by the carbon content of the metal. Thus, zirconium acts as a getter for carbon monoxide at elevated temperatures, while tungsten, chromium, and iron may form carbon monoxide gas. 

This is a batch process that is made complex by the fuel cladding and radioactivity. A typical fuel assembly for a PWR contains about 250, 0.37-inch zirconium-clad rods 12-feet long containing in total about 1200 lb of U02. The assembled rods are mechanically sheared into 1- to 2-inch lengths and dropped into a perforated basket. This is placed in the dissolver tank where the uranium oxide is dissolved as discussed above. The basket then is removed from the dissolver, and the zirconium hulls and associated hardware therein are dumped into containers, compressed, sealed, and sent to transuranic waste storage. Ultimately, they will go to a disposal facility. 

Select an optimal option on removing inanium-zirconium SNF from storages of... 

Under the attack of one equivalent OH in H2O, MeO in MeOH, or pure NH3 a silicon vertex was removed from the c/oso-cluster l.[21 A plausible mechanistic sequence for the degradation involves as the first step formation of an adduct consisting of the nucleophile and the c/oso-cluster. Afterwards this adduct should react with a protic solvent to give the isolated reaction product. In order to get indications for the expected adduct we studied the attack of nucleophiles in an aprotic solvent. Three types of nucleophiles were studied in this reaction. In the case of the dialkylamide nucleophile best results were achieved from the reaction of the close-cluster with transition metal amides of zirconium and tantalum,17,81 The anionic adduct cluster features a dialkylamide bridging both silicon centres of the silaborane cluster. 

Additional haUdes can be removed from the above insoluble ammonolysis product by reaction with potassium imide to form zirconium imide [87227-54-1]... 

Topical zirconium can cause hypersensitivity granulomas in sensitized persons, which has led to the removal of zirconium salts from antiperspirants (SEDA-22, 242). Complexes of zirconium and aluminum are non-sensitizing and are still commonly used as active ingredients in topical antiperspirants. However, a granulomatous reaction to this material has been reported (1). 

S8], and phosgene impurities have been removed from silicon(IV) chloride by passing over titanium slag or a mixture of zirconium(IV) silicate and coke at 800 C [1870],... 

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