Radionuclide Migration Through Fractured Granite. Laboratory Studies

Abstract

Radionuclide migration has been studied in natural fractures in granite blocks of up to 30 cm in length. Results are reported for four migration experiments involving synthetic groundwaters containing tritiated water, 95mTc, 75Se, 137Cs, or 60Co-labelled natural colloids, which were injected in to the fractures at flow rates of 0.4-0.45 mL/h, giving residence times in the fractures of up to 15 h. Also presented are the results of the post-experiment analyses, including an autoradiograph of one of the fracture surfaces, and the spatial distribution of the sorbed radionuclides determined by y-scanning and selective chemical extractions.