Characterization of Solidified Cement Bearing Organo-Clay after Adsorption of Perchlorate as a Surrogate of an Anionic Radionuclide

Abstract

Nuclear Power Plant (FDNPP) accident produced much amount of radioactively contaminated water at the Great East Japan Earthquake. 137 Cs and 90 Sr have been focused to remove from the contaminated water using zeolite types of adsorbents. Other radionuclides have been treated and removed separately by Advanced Liquid Processing System (ALPS), where resin is used to immobilize anions. However, these kinds of spent-adsorbents are not suitable for long-terms burying because of its instability, and the representative anionic radionuclides ( 129 I, 36 Cl, 99m Tc and 79 Se) have quite long half-life (10 5 -10 7 years). Montmorillonite (Mt) is an useful adsorbent because of its high chemical stability and large cationic exchange capacity. In the present work, surfactant modified Mt (OMt) has been developed using hexadecylpyridium chloride for adsorption of ClO 4- , which is a surrogate of 99m TcO 4- . For stabilization of spent-OMt, cement solidification was examined with varying the ratio of spent-OMt content. To evaluate its chemical and physical stability, soaking and compressive strength tests were conducted. As a result, it was revealed by FTIR and 29 Si-NMR that with increase in OMt contents, the linkage of calcium silicate hydrate was more developed.