Analytical Characterization of UO2 Fuel

The processing of UO2 for manufacturing nuclear fuel involves two stages powder production followed by fabrication of ceramic UO2 pellets. The processing of the powder includes homogenization, that is, blending to ensure uniform particle size 

The 0 U ratio is needed for predicting the sintering behavior of the powder in pellet production. The nranium content (of the dry sample after moistnre determination) and isotopic composition are reqnired for estimation of the performance of the fuel. The impurity content is needed for calculating the EBC. The methods ontlined in the document (C696 2011) cover a broad range of analytical techniqnes some of which are listed in Table 2.6. 

These include chemical methods (reduction by ferrons snlfate and titrimetric determination), gravimetric methods for 0 U ratio, moistnre analysis by conlomet-ric techniques, and determination of H, C, N, Cl, and E with a specific method for each of these elements. In addition, the isotopic composition is determined by mass spectrometric methods and several metallic and nomnetallic impnrity elements are determined by spectrochemical methods. 

Some detailed examples of ASTM protocols for the characterization of UO2 are presented later in order to demonstrate the procedures. Determination of uranium, oxygen, and the 0 U atomic ratio by the ignition (gravimetric) impnrity correction method is part of the general test methods for UO2 (C696 2011). The sample (5-10 g of powdered 

Uranium by ferrous sulfate reduction in phosphoric acid and dichromate titration method C1267 Test method for uranium by iron (II) reduction in phosphoric acid followed by chromium (VI) titration in the presence of vanadium 

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