Status report on LWR spent fuel IAEA leach tests

Spent light-water-reactor (LWR) fuel with an average burnup of 28,000 MWd/MTU was leach-tested at 25/sup 0/C using a modified version of the International Atomic Energy Agency procedure. Leach rates were determined from tests conducted in five different solutions: deionized water, sodium chloride (NaCl), sodium bicarbonate (NaHCO/sub 3/), calcium chloride (CaCl/sub 2/) and Waste Isolation Pilot Plant B brine solutions. Elemental leach rates are reported based on the release of /sup 90/Sr + /sup 90/Y, /sup 106/Ru, /sup 137/Cs, /sup 144/Ce, /sup 154/Eu, /sup 239 + 240/Pu, /sup 244/Cm and total uranium. After 467 days of cumulative leaching, the elemental leach rates are highest in deionized water. The elemental leach rates uin the different solutions generally decreased from deionized water to the 0.03M NaCl solution to the WIPP B brine solution to the 0.03M NaHCO/sub 3/ solution and was a factor of 20 lower in 0.015M CaCl/sub 2/ solution than in deionized water. The leach rates of spent fuel and borosilicate waste-glass were also compared. In sodium bicarbonate solution, the leach rates of the two waste forms were nearly equal, but the glass was increasingly more resistant than spent fuel in calcium chloride solution, followed by sodium chloride solution, WIPP B brine solution and deionized water. In deionized water the glass, based on the elemental release of plutonium and curium, was 50 to 400 times more leach resistant than spent fuel.