Three Year Experimental Study of Leaching Phenomena from Low Level Radioactive Homogeneous Cement-Based Waste Forms.

Abstract This study was carried out in order to demonstrate the safety of homogeneous cementbased waste forms (hereinafter called cement forms) for BWR's low level radioactive wastes as engineered barriers. Eighteen full scale simulated cement forms were manufactured with the addition of 137Cs, 66Co and 90Sr. Leaching tests on these forms were carried out for approximately three years. In order to study the relationship of leachability to environments at disposal sites, this Three Year Leaching Test was conducted for three kinds of environmental conditions, sea water, land water and soil. After the tests, all of these forms were cut to measure the distribution of the radionuclide's density within them. In case of the soil tests, the distribution of radionuclide in the soil was also measured. The radionuclide leachability results reveal that 60Co was almost completely retained in the cement forms and that 137Cs leached from cement forms was mostly adsorbed by the soil. On the other hand, 90Sr was not trapped in the forms and leaked through the soil around them in retard. This study also showed that simulated cement forms buried in the soil were more physically and chemically stable, and had longer term stable radionuclide containment capability than those which were submerged in sea or land water.