HWAHAK KONGHAK, Vol.34, No.3, 270-276, June, 1996
석탄회재-점토 혼합충전층에서의 핵종이동에 관한 연구
Radionuclide Migration through the Mixed Beds of Fly Ash and Clay
초록
방사성폐기물처분장의 충전물로서 석탄회재의 적용가능성을 확인하기 위해서, 점토와 석탄회재의 혼합충전층에서의 방사성핵종 이동현상을 실험을 통하여 규명하고자 하였다. 혼합충전층에서의 Sr-90에 대한 확산실험은 Back to Back Diffusion Method을 사용하였다. 실험결과, 혼합충전층에서의 Sr-90이동이 석탄회재 물질에서는 대부분 공극확산에 의해 이루어지고, 점토물질에서는 주로 표면학산에 의해 이루어지는 것으로 나타났다. 혼합충전층에서의 확산계수는 4.33 X 10 -12-2.06 X 10-11 m2/s로 지금까지 많이 사용되어 온 점토 100%에서의 확산계수보다 훨씬 작은 값을 나타내어, 석탄회재와 점토의 혼합충전물이 점토 단일물질보다 더 우수한 것으로 나타났다.
The migration characteristics of radionuclide in the mixed beds of fly ash and clay were studied to investigate the applicability of fly ash as backfill material in radioactive waste repositories. In this study, the back to back diffusion method was employed in the investigation of the diffusion phenomena of Sr-90. The experimental data showed that the migration of cation took place through pore diffusion in the bed of fly ash, whereas in the bed of clay, it occurred through surface diffusion. Therefore, the diffusivities of cation in the mixed beds of fly ash and clay were calculated in terms of the migration characteristics of each material. The results indicated that the diffusivity of Sr-90 varied from 4.33 X 10-12 to 2.06 X10-11m/s in the mixed beds of fly ash and clay in which the fly ash content was in the range of 20 to 100 wt%. Thus, the mixed bed of fly ash and clay was found superior to the clay bed as a backfill material in radioactive waste repositories.
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