Spent fuel dissolution

In direct geological depository of the spent fuel, dissolution of UO2 matrix into groundwater plays a key role for the release of the radionuclides to the biosphere. Therefore mechanism of... 

Adachi, T., Ohnuki, M. et al. 1990. Dissolution study of spent PWR fuel Dissolution behavior and chemical properties of insoluble residues. Journal of Nuclear Materials, 174, 60-71. 

Gray, W. J., Leider, H. R. Steward, S. A. 1992. Parametric study of LWR spent fuel dissolution kinetics. Journal of Nuclear Materials, 190, 46-52. 

Oversby, V. M. 1999. Uranium Dioxide, SIMFUEL, and Spent Fuel Dissolution Rates - A Review of Published Data. Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden, TR-99-22. 

Quinones, J., Grambow, B., Loida, A. Geckeis, H. 1996. Coprecipitation phenomena during spent fuel dissolution. Part 1 Experimental procedure and initial results on trivalent ion behavior. Journal of Nuclear Materials, 238, 38-43. 

This review will exclusively deal with studies related to solvent-extraction processes (neither solid-phase precipitation nor ion-exchange chromatography) aiming at separating trivalent actinides from PUREX raffinates or spent-fuel dissolution... 

Adachi, T., Ohnuki, M., Yoshida, N., Sonobe, T., Kawamura, W., Takeishi, H., Gunji, K., Kimura, T., Suzuki, T., Nakahara, Y., Muromura, T., Kobayashi, Y., Okashita, H., Yamamoto, T. 1990. Dissolution study of spent PWR fuel Dissolution behavior and chemical properties of insoluble residues. Journal of Nuclear Materials 174(1) 60-71. 

To demonstrate the use of the findings presented above the focus will now be turned to the process of spent nuclear fuel dissolution under deep geological repository conditions. 

Fig. 5. Dynamics of spent nuclear fuel dissolution taking into account UO2 oxidation by H2O2, H2 production and noble metal particle catalyzed reduction of...

Long term spent nuclear fuel dissolution experiments show that the rate of dissolution decreases with time and eventually the process appears to stop. The inhibition is strongly connected to the radi-olytical production of H2 in the system. The dynamics of such a system is illustrated in Fig. 5. 

Wilson, C. N. 1990. Results from NbfWSl series 3 spent fuel dissolution tests. Pacific Northwest Laboratory, Report PNL-7170. 

Wilson, C. N., and C. J. Bruton. 1990. Studies on spent fuel dissolution behavior under Yucca Mountain repository conditions. Nuclear Waste Mgmt. III. Ceramic Trans. 9 423-41. 

SKI (2007) Spent Fuel Dissolution and Source Term Modelling in Safety Assessment. SKI Report 2007 17. 

AH operating facilities shear the spent fuel elements into segments several centimeters long to expose the oxide pellets to nitric acid for dissolution. This operation is often referred to as chop-leach. The design and operation of the shear is of primary importance because (/) the shear can be the production botdeneck, and (2) the shear is the point at which tritium and fission gases are released. 

In order to assess the integrity of the system, we should know what kind of reactions would take place when the groundwater invades and the overpack is corroded. Consequently, the solidified waste or spent fuel itself will be in contact with groundwater. Since the waste would still be seriously activated, radiolysis of groundwater will take place and change the chemical condition, which might affect the dissolution of the solidified waste or UO2 of the spent fuel. 

Dissolution of the oxidized portion of the surface of the spent fuel, that is, the release of uranium(VI) to the solution. This is described by the following expression ... 

Merino, J., Cera, E., Bruno, J., Erikssen, T., Quinones, J. Martinez-Esparza, A. 2001. Long term modelling of spent fuel oxidation/ dissolution under repository conditions. ICEM 01. Session 23, V. The 8th International Conference on Radioactive Waste Management and Environmental Remediation. 30 September-4 October 2001, Bruges (Brugge), Belgium. 

Ahn, T. M. 1996. Long-Term Kinetic Effects and Colloid Formations in Dissolution of LWR Spent Fuels. US Nuclear Regulatory Commission, NUREG-1564. 

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