THE RELEASE OF URANIUM, PLUTONIUM, CESIUM, STRONTIUM, TECHNETIUM AND IODINE FROM SPENT FUEL UNDER UNSATURATED CONDITIONS

Drip tests to measure radionuclide release from spent nuclear fuel are being performed at 90 degrees C at a drip rate of 0.75 ml every 3.5 d ays. The test conditions are designed to simulate the behavior of spen t fuel under the unsaturated and oxidizing conditions expected in a po tential repository at Yucca Mountain. The U-238, Pu-239, Cs-137, Sr-90 , Tc-99, and I-129 content in the leachate after 581 days of testing i s reported. These data provide valuable information for estimating the release of long-lived radionuclides. A comparison is made between our results and those of other researchers. The Tc-99 release fractions a re suggested to be representative of matrix dissolution.