EXPERIENCE ON WET STORAGE SPENT FUEL SIPPING AT IEA-R1 BRAZILIAN RESEARCH REACTOR

The IEA-R1 research reactor of the Institute de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP) is a pool type reactor of B&W design, that has been operating since 1957 at a power of 2 MW. Irradiated (spent) f uels have been stored at the facility during the various years of oper ation. At present there are 40 spent fuel assemblies at dry storage, 7 9 spent fuel assemblies at wet storage and 30 fuel assemblies in the c ore. The oldest fuels ar;e of United States origin, made with U-Al all oy, both of LEU and HEU MTR fuel type. Many of these fuel assemblies h ave corrosion pits along their lateral fuel. plates. These pits origin ate by galvanic corrosion between the fuel plate and the stainless ste el storage racks. As a consequence of the possibility of sending the i rradiated old fuels back the U.S.A., sipping tests were performed with the spent fuel assemblies. The reason for this was to evaluate their Cs-137 leaking rate, if any. This work describes the procedure and met hodology used to perform the sipping tests with the fuel assemblies at the storage pool, and presents the results obtained for the Cs-137 si pping water activity for each fuel assembly. A correlation is made bet ween the corrosion pits and the activity values measured. A Cs-137 lea king rate is determined and compared to the criteria established for c anning spent fuel assemblies before shipment. (C) 1998 Elsevier Scienc e Ltd.