Uranium-dioxide icebreaker pressurized water reactor fuel

Uranium-dioxide icebreaker pressurized water reactor fuel 

Not much is known of the behavior of UO2 fuel pellets in sea water. A review of available data by Carter [22] enabled an estimated grain dissolution rate of 30 x 10 g-cm -d to be determined for UO2 fuel pellets. For fuel pins of 4.S mm diameter, of regular geometiy and 10 g-cm density, this equates to a dissolution rate of 0.0011 mm-a. The same reference summarizes work by Shoesmith and Sunder [2S] in which the release of activity from oxide fuel in a waste repository vault is considered. This suggests  

However, because of the difficulties and lack of information in estimating the rates of radionuclide release from grain boundaries, the model assumes an instantaneous release from the fuel surface and grain boundaries once sea water comes into contact with the fuel. As a conservative estimate, this is assumed to account for 20% of the total fission product and actinide inventory in the fuel. Similarly, since the extent of damage to the Zr-Nb alloy cladding around the fuel is unknown, the model assumes that cladding is ineffective as a barrier to sea water and radionuclide release. 

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