In order to determine in how far the Boom Clay (BC) properties and alpha-activity influence the dissolution kinetics of spent fuel, static dissolution tests have been performed with 6 different types of alpha-doped UO2, representing fuel ages ranging between 150-90,000years. The experiments have been carried out in different BC media at room temperature and in an anoxic atmosphere for 90-720days. The uranium activity in the clay fraction was determined to be much higher than the U-activity in the leachates, which has been mainly ascribed to the high retention capacity of the BC. The initial corrosion rates were all found to be high and quite similar, ~300µg • m-2 • d-1, decreasing with time towards an average rate less than 30µg • m-2 • d-1. These preliminary results reveal that the fuel activity does not seem to have an effect on the UO2 dissolution rates. This hypothesis seems to be supported by other literature data, suggesting the presence of an alpha-activity threshold between 107-108Bq/g UO2 below which no correlation between the alpha-activity and the dissolution rate exists. In order to proof this assumption and to study the partition/redistribution of U during leaching, sequential extraction experiments are currently in progress.
|Title of host publication||Symposium Proceedings. Scientific Basis for Nuclear Waste Management XXIX|
|Place of Publication||Warrendale, United States|
|State||Published - Jun 2006|
|Event||2005 - MRS : 29th International Symposium on the Scientific Basis for Nuclear Waste Management - Gent|
Duration: 12 Sep 2005 → 16 Sep 2005
|Conference||2005 - MRS|
|Period||2005-09-12 → 2005-09-16|