Yellow cake composition

Yellow cake is a complicated mixture of salts and oxides, the composition of which approximates to (NH4)2U207 but is dependent on the method by which it is produced (see p. 276 of ref 2). 

Uranium is deposited widely in the Earth s crust, hence it has few ores, notably the oxides uraninite and pitchblende. The ores are leached with H2SO4 in the presence of an oxidizing agent such as NaClOs or Mn02, to oxidize all the uranium to the (+6) state as a sulfate or chloride complex. On neutralization with ammonia a precipitate of yellow cake , a yellow solid with the approximate composition (NH4)2U207 is formed. This is converted into UO3 on ignition at 300 °C. This can be purified further by conversion into uranyl nitrate, followed by solvent extraction using tributyl phosphate in kerosene as the extractant. 

The existence of some of these databases is acknowledged publicly. For example, as mentioned earlier, LLNL has a database that includes 1800 samples of yellow cake (Kristo and Dirnet 2013), and the Nuclear Forensics Analysis Center (NFAC) in Savannah River National Laboratory (SRNL) provides support for the FBFs Radiological Evidence Examination Facility (REEF) (Nichols 2011). The latter contains a database of spent nuclear fuel from several reactors in the United States and other countries. An example of the processing of interdicted nuclear material at REEF uses traditional forensics combined with nuclear forensics to determine the origin and make attribution. The results of the isotopic measurements are compared to known compositions in the database based on reactor physics models (see flowchart in Figure 5.19). 

Place 3000 milliliters of 40% nitric acid into a beaker, and then gently heat this mixture to about 30 Celsius. Thereafter, carefully mix the moist filter cake, prepared at the end of step 1 to the nitric acid solution over a period of about 30 minutes, while stirring the nitric acid and keeping its temperature around 30 Celsius. Immediately after the first addition of the filter cake, nitrogen oxide gases will be evolved, followed by the formation of a foam (the foam will dissipate after about 10 minutes). After the addition, raise the temperature of the mixture to 95 Celsius, and then hold this temperature for 1 hour. After heating for 1 hour, remove the heat source and allow the reaction mixture to cool to room temperature. Note A precipitate will form. When the reaction mixture reaches room temperature, filter-off the precipitated product, wash with 300 milliliters of 2% nitric acid, and then with 600 milliliters of cold water. Then vacuum dry or air-dry the product. The result will be pale yellow crystals, well suitable for use in preparing lead styphnate, or styphnic acid compositions. 

GUNPOWDER, or black powder, is a mixture of saltpetre, sulphur and carbon. Early Chinese recipes used equal weights to make a fast burning, but not explosive, powder. A composition that matches well the chemistry ctf the reaction is 15 parts saltpetre, 2 parts sulphur and 3 parts charcoal. Mix the ingedients while damp, using pressure to make a dense cake which can be broken into grains when dry. For most explosive results use refined saltpetre. Metal salts can add colour to the explosion, e.g. sodium salts for yellow or orange, potassium salts for purple, and strontium salts for red. This is the basis of fireworks. 

FIGURE 14.3 Formation of dye cake layer on the surface of NF-PA composite membrane after 4 h of operation using aqueous dye solution containing 1000 ppm Direct Yellow 8. (Reprinted from Mo, J.H., Lee, Y.H., Kim, J., Jeong, J.Y., and legal, 1., Dyes Pigm., 76, 429-434, 2008. With permission.)... 

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