Argentine activities related to the development of low enriched fuel elements

Within the framework of the RERTR Program and supported by the technical cooperation work agreed upon between the U.S.A. and Argentina in May 1979, the CNEA Nuclear Fuel Department - Low Enriched Fuel Elements Project (ECBE Project), has carried on its own program for developing fuels with low enrichment for research and test reactors. Up to the present, its main objective has been to replace the highly enriched fuel used in its only reactor (RA-3) for research, development and radioisotopes production. The basic stages of the Argentine Program are shown in Table 1. At a meeting held in Vienna in March, 1980, the CNEA stated that its development of fuels with low enrichment would be in two fuel lines: UAlx-Al and U3O8-Al, and that its aim would be to reach uranium densities of 18-2.2 g/cm3 for the UAIx-Al line and 2.4-3.0 g/cm3 for the U3O8 line. At the international meeting held at ANL in November, 1980, and after having received depleted uranium and uranium with 20% and 45% enrichment (purchased from the U.S.A. for manufacturing miniplates and possible standard fuels) to carry on the proposed development, CNEA anticipated -- after its first tests -- that the conditions were satisfactory for reaching uranium densities of 2.4-3.0 g/cm3 in U3O8-Al fuel and of 2.4 g/cm3 in UAIx-Al fuel. In February 1981, after Argentina accepted the obligation of paying for the irradiation service, authorization was obtained for irradiating miniplates in the Oak Ridge Reactor within the RERTR Program. In June 1981, the first set of miniplates was sent to Oak Ridge National Laboratory (ORNL). The maximum actual densities reached at that time were 3.12 g/cm3 with U3O8-Al and 2.52 g/cm3 with UAlx-Al. During a visit of the CNEA Project Technical Manager to the Argonne National Laboratory (ANL) in July 1981, and after exchanging ideas with ANL professional staff, the CNEA decided to incorporate a new line of development, that of U3Si-Al. Three months later, in October 1981 a second set of miniplates was sent to ORNL including this new development. The densities then reached were within the range of 3.12-3.58 g/cm3 for U3O8-Al, 2.99-3.09 g/cm3 for UAl2-Al and 5.18-6.10 g/cm3 for U3Si-Al. Thus, Table shows very clearly that our initial objectives have been surpassed by far. If further miniplates can be irradiated, it is our purpose to reach uranium densities of 3.5 g/cm3 in UAl2-Al and 6.5 g/cm3 in U3Si-Al. The present status (on November 1st, 1982) of the CNEA miniplates being irradiated in the Oak Ridge Reactor (ORR) is shown. The plates in module 9 have reached 87% burnup and those in module 6 have reached 53% burnup. Up to now, their performance has been satisfactory. The estimated burnups reached by the miniplates in the different positions are shown in the irradiation history summary report. On the basis of the data - Ranges of Specifications for ANL, ORNL, EG and G, NUKEM and CNEA Miniplates for Irradiation in the ORR, and data of the IAEA Safety and Licensing Guidebook (March 1982), it is shown that the CNEA has achieved the highest loadings in the UAlx-Al, U3O8-Al and U3Si-Al miniplates being tested in the ORR. In addition, the CNEA is the only fabricator of miniplates with LEU UAl2-Al fuel