3-YEAR EXPERIMENTAL-STUDY OF LEACHING PHENOMENA FROM LOW-LEVEL RADIOACTIVE HOMOGENEOUS CEMENT-BASED WASTE FORMS

This study was carried out in order to demonstrate the safety of homog eneous cement-based waste forms (hereinafter called cement forms) for BWR's low level radioactive wastes as engineered barriers, Eighteen fu ll scale simulated cement forms were manufactured with the addition of Cs-137, Co-60 and Sr-90. Leaching tests on these forms were carried o ut for approximately three years. In order to study the relationship o f leachability to environments at disposal sites, this Three Year Leac hing Test was conducted for three kinds of environmental conditions, s ea water, land water and soil. After the tests, all of these forms wer e 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 reve al that Co-60 was almost completely retained in the cement forms and t hat Cs-137 leached from cement forms was mostly adsorbed by the soil. On the other hand, Sr-90 was not trapped in the forms and leaked throu gh the soil around them in retard. This study also showed that simulat ed cement forms buried in the soil were more physically and chemically stable, and had longer term stable radionuclide containment capabilit y than those which were submerged in sea or land water.