Leaching characteristics of paraffin waste forms generated from Korean nuclear power plants

Leaching tests of paraffin waste forms including boric acid, cobalt, stront ium and cesium were performed to investigate the leaching characteristics o f paraffin waste forms which had been generated in Korean nuclear power pla nts. The leaching tests were conducted according to ANSI/ANS-16.1 test proc edure and the cumulative fractions leached (CFLs) of boric acid, cobalt, st rontium and cesium were obtained. The compressive strength before and after the leaching test was measured for various waste forms with different mixi ng ratios of boric acid to paraffin. It was observed that boric acid and ot her nuclides immobilized within paraffin waste forms were congruently relea sed and the leaching rates were influenced by reacted layer depth as the di ssolution reaction progressed. A shrinking core model based on the diffusio n-controlled dissolution kinetics was developed in order to simulate the te st results. The CFLs and the leaching rates were well expressed by the shri nking core model and the cross-sectional view of specimen after the test de monstrated the applicability of this model with the shrinking dissolution f ront to the leaching analysis of paraffin waste forms. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.