Summary of Results from the Series 2 and Series 3 NNWSI (Nevada Nuclear Waste Storage Investigations) Bare Fuel Dissolution Tests

摘要

The Nevada Nuclear Waste Storage Investigations (NNWSI) Project is studying dissolution and radionuclide release behavior of spent nuclear fuel in Nevada Test Site groundwater. Specimens were tested for multiple cycles in J-13 well water. The Series 2 tests were run in unsealed silica vessels under ambient hot cell air (25 sup 0 C) for five cycles for a total of 34 months. The Series 3 tests were run in sealed stainless steel vessels at 25 sup 0 C and 85 sup 0 C for three cycles for a total of 15 months. Selected summary results from Series 2 and Series 3 tests with bare fuel specimens are reported. Uranium concentrations in later test cycles ranged from 1 to 2 mu g/ml in the Series 2 Tests versus about 0.1 to 0.4 mu g/ml in Series 3 with the lowest concentrations occurring in the 85 sup 0 C tests. Preferential release of fission products Cs, I, Sr and Tc, and activation product C-14, was indicated relative to the actinides. Tc-99 and Cs-137 activities measured in solution after Cycle 1 increased linearly with time, with the rate of increase greater at 85 sup 0 C than at 25 sup 0 C. 8 refs., 8 figs., 3 tabs. (ERA citation 13:021110)