Static dissolution tests of alpha-doped UO2 under repository relevant conditions: Influence of Boom Clay and alpha-activity on fuel dissolution rates

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Abstract

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.

Details

Original languageEnglish
Title of host publicationSymposium Proceedings. Scientific Basis for Nuclear Waste Management XXIX
Place of PublicationWarrendale, United States
Pages481-488
Publication statusPublished - Jun 2006
EventMRS 2005. 29th International Symposium on the Scientific Basis for Nuclear Waste Management - SCK•CEN, Gent, Belgium
Duration: 12 Sep 200516 Sep 2005

Conference

ConferenceMRS 2005. 29th International Symposium on the Scientific Basis for Nuclear Waste Management
Country/TerritoryBelgium
CityGent
Period2005-09-122005-09-16

Keywords

  • alpha-radiolysis, dissolution rates, leach tests, Boom clay, spent fuel

ID: 199459