사질토에 대한 ⁶⁰Co, ⁸⁵Sr, ¹³⁷Cs의 수착특성평가 실험을 수행하였다. 수착반응속도에 대해 살펴보고, 가평형상태에서 분배계수값을 측정하여 세 핵종간의 차이를 비교평가하였다. 순차적 화학추출법을 도입하여 방사성핵종들이 사질토에 수착하는 주된 유형과 가역성을 정량적으로 평가하였다. 순차적 화학추출법으로서 도입한 공정은 지하수, CaCl₂, KCl, KTOX(K₂C₂O₄+NH₂OH-HCl) 등이며, 이로써 파악하고자 하는 수착유형은 지하수조건에서 가역적 수착, 이온교환, 철망간산화물과의 결합, 비가역적 고착 등이다. ⁸⁵Sr은 주로 매질표면에 가역적인 이온교환반응을 하였다. ⁶⁰Co는 이온교환, 철망간산화물과의 결합, 비가역적 고착 등이 비슷한 비율로 나타났다. ¹³⁷Cs는 이온교환이 주로 나타나고 비가역적 고착도 상당비율로 나타났다. 세 핵종간 상대적인 이동성 및 가역성은 ⁸⁵Sr>⁶⁰Co>¹³⁷Cs순이었다.

Sorption characteristics of ⁶⁰Co, ⁸⁵Sr and ¹³⁷Cs onto sandy soil are studied experimentally. Sorption kinetics and distribution coefficients at a quasi-equilibrium are investigated. Sorption strength among 3 species is explained with sorption mechanism and surface complexation concept. A sequential chemical extraction method is introduced to find out sorption modes and reversibility. Chosen reagents for extraction are groundwater, CaCl₂, KCl, and KTOX(K₂C₂O₄+NH₂OH-HCl). Considered sorption types are reversible sorption in a groundwater condition, ion exchange, association with ferro-maganese oxides, and irreversible fixation. Strontium sorbed onto the sandy soil surface mainly by fast and reversible ion exchange reaction. However, cobalt and cesium ions do not sorb by a simple process. In the case of cobalt, three kinds of sorption types were occurred competitively among ion exchange, association with ferro-manganese oxides and irreversible fixation. The main sorptive binding of cesium was ion exchange reaction, while irreversible fixation was the secondary importance. The order of migration mobility for the three radionuclides was ⁸⁵Sr>⁶⁰Co>¹³⁷Cs in the sandy soil.

Sorption Sequential Chemical Extraction Ion Exchange Irreversible Fixation

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