Mathematical Modeling of Radon Emanation

概要

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It is well known that radon emanation is affected by moisture. The models which explain radon emanation can be considered to come in three types. One is to predict the maximum possibility of radon emanation assuming uniform distribution of radium in a solid grain independent of moisture. The other two are to explain moisture effect on radon emanation, but their aims are different from each other. The first of them aims to demonstrate a theory explaining microscopic phenomena of radon emanation employing observed macroscopic phenomena of radon emanation under moist condition. The second aims to predict the leveling-off value of radon emanation under moist conditions employing an observed data of radon emanation under dry condition. The present paper develops a close-packed spherical grain model which belongs to the last type of model just mentioned. This model is oriented to contribute to the safety assessment of uranium-bearing waste disposal. Uranium-bearing waste generates radon as one of the uranium decay chain daughter nuclides. They will build up until about 200,000 years after disposal. At that far future, rainwater may well come into contact with the disposed waste and increase radon emanation. Therefore, leveling-off radon emanation has to be employed for the safety assessment. The model by the present paper is best oriented for this purpose.
一般社団法人日本原子力学会の論文
2004-02-25