Spent Fuel at 85°c in Natural Ground Water*

Semi-static dissolution tests using pressurized water reactor spent fuel rod segments and NNWSI reference J-13 well water 1n sealed stainless steel vessels at 85*C are being conducted In support of the Waste Package Task of the NNWSI Project. Test specimens include: bare fuel plus the empty cladding hulls, fuel rod segments with artificially induced cladding defects and water-tight end caps, and undefected fuel rod segments with water-tight end caps. The test conditions approximate those expected In the proposed NNWSI Project repository when the waste package has cooled sufficiently to allow water to enter a breached container and contact the fuel rods, some of which may exhibit various degrees of cladding failure. Periodic solution samples (unflltered and filtered) were analyzed for most radionuclides for which cumulative release limits are listed by the U.S. Environmental Protection Agency. Results from the first six-month cycle of the 85*C tests are presented and are compared with results from the first cycle of a previous test series run at 25*C In fused silica test vessels.