[en] Even since its creation in 1950, the Comision Nacional de Energia Atomica (CNEA) pays special attention to the development of activities related to the production of radioisotopes, ionising radiations and its applications, promoting producing and supporting them. In 1953, with the installation of an Crockroft-Walton electrostatic accelerator and in 1954 whit the acquisition of an synchrocyclotron, CNEA started early in the production of radioisotopes. After that, with the installation of the RA-1 and RA-3 research reactors baby cyclotrons and processing plants, CNEA complete and complement all infrastructure dedicated to production activities. In this sense, in 1994 a Cyclotron Facility for radioisotope production started its operations at Ezeiza Atomic Center. The cyclotron installed is a isochronous, negative ion, CP-42 accelerator, mainly used for the production of short and medium half life radioisotopes for nuclear medicine. With the object of covering the local demand of these radioisotopes some improvements were made in the cyclotron in order to increase the beam current. Finally, a brief description of the processes for the production of Tl-201, FDG (F-18) and I-123 is made. (author)

[en] The history, equipment, and operations of the cyclotron facility in the Ezeiza Atomic Center are discussed

[en] In the framework of the CRP, our country has worked on the optimization of synthesis, quality control, in vitro and in vivo evaluation of ¹²³I radiopharmaceuticals based on peptides. We have worked on selective labelling procedures using prosthetic groups with the goal to create a strong carbon-halogen bond, which will be resistant to in vivo dehalogenation and other catabolic processes. The method utilizes the labelling agent, reactive with ε-amino lysine groups, N-succinimidyl 3-iodobenzoate. This conjugation agent was radiolabelled by using an organometallic intermediate to facilitate the reaction. The organometallic N-succinimidyl 3-(tri-nbutylstannyl) benzoate (ATE) was made in a three-step synthesis pathway. The yields for the reactions of this synthetic pathway were: 56.4% for the first reaction, 67% for the second, and 58% for the ATE (469 mg, 0.92 mmol). Because of only 0.1 μmol of ATE is needed for the labelling of peptides, from one batch of organic synthesis we obtained ATE to make more than 9000 labelling. The N-succinimidyl 3-(tri-n-butylstannyl) benzoate (ATE) was radiolabelled in 55-85% radiochemical yield to obtain the N-succinimidyl 3-iodobenzoate ( [¹³¹I]SIB ). Parameters like reactive concentration and isolation method of the labelling agent were studied. The labelling agent [¹³¹I]SIB was subsequently conjugated to a human IgG and a peptide. A chemotactic peptide was used as a model peptide. A potent chemotactic peptide N-formyl-norleucyl-leucyl-phenylalanyl-norleucyltyrosyl- lysine (fNleLFNleYK) was derivatized by reaction with the labelling agent in 59-75% of radiochemical yield. This derivatized peptide bound specifically to human polymorphonuclear leukocytes in vitro and exhibited biological activity in a superoxide production assay. Binding affinity IC₅₀: 36 nM, in the displacing of [³H]fMLF binding, and IC₅₀: 68 nM, in the displacing of the fNleLFNleYK-[¹³¹I]SIB conjugate, for the derivatized peptide were obtained. Because of both IC₅₀ were higher of than those for the underivatized peptide the affinity of the derivatized peptide is somewhat lower than that. With the HPLC condition used the peaks corresponding to ¹³¹I-labelled peptide, unlabelled peptide and [¹³¹I]SIB are well resolved; so carrier free radiolabelled peptide can be isolated. Under these circumstances, the specific activity of the radiolabelled peptide is limited only by the specific activity of the radioiodine. The thyroid uptake of the radioiodinated peptide was very low. This result indicate that this radiohalogenation method yield a labelled molecule very stable to in vivo dehalogenation. Rapid localization (within 1 h) of radiolabelled chemotactic peptide at sites of experimental infection was observed. (author)

[en] Since last RRFM meeting, CNEA has continued on new LEU fuel and target development activities. Main goals are the plan to convert our RA-6 reactor from HEU to a new LEU core, to get a comprehensive understanding of U-Mo/Al compounds phase formation in dispersed and monolithic fuels, to develop possible solutions to VHD dispersed and monolithic fuels technical problems, to optimize techniques to recover U from silicide scrap samples as cold test for radiowaste separation for final conditioning of silicide spent fuels. and to improve the diffusion of LEU target and radiochemical technology for radioisotope production. Future plans include: - Completion of the RA-6 reactor conversion to LEU; - Improvement on fuel development and production facilities to implement new technologies, including NDT techniques to assess bonding quality; - Irradiation of miniplates and full scale fuel assembly at RA-3 and plans to perform irradiation on higher power and temperature regime reactors; - Optimization of LEU target and radiochemical techniques for radioisotope production. (author)

[en] During 2005 CNEA has continued and developed new RERTR activities. Main goals are the plan to convert our RA-6 reactor from HEU to a new LEU core, to get a comprehensive understanding of U-Mo/Al compounds phase formation in dispersed and monolithic fuels, to develop possible solutions to VHD dispersed and monolithic fuels technical problems, to optimize techniques to recover U from silicide scrap samples as cold test for radiowaste separation for final conditioning of silicide spent fuels. and to improve the diffusion of LEU target and radiochemical technology for radioisotope production. Future plans include: - Completion during 2006 the RA-6 reactor conversion to LEU. - Improvement on fuel development and production facilities to implement new technologies, including NDT techniques to assess bonding quality. - Irradiation of miniplates and full scale fuel assembly at RA-3 and plans to perform irradiation on higher power and temperature regime reactors. - Optimization of LEU target and radiochemical techniques for radioisotope production. (author)

[en] Full text: During 2004, CNEA performed several RERTR activities, including: LEU Very High Density Fuel development: two national technical meetings has taken place. During 2004 works are being focused on: - U-Mo powder development and fabrication, - research on U-Mo based ternary systems, - Mo-Al diffusion couples out-of-pile experiments, - 3-D thermal mechanical modelling of fuel behaviour under irradiation, - atomistic modelling and experimental fuel particle and sheet coating, - development of new matrix, new fuel particle and sheet, and new cladding, - development of advanced welding techniques to be applied on monolithic fuels. LEU high density fuel fabrication activities: - status of fabrication tasks of silicide fuels for RRR reactor. LEU radioisotope production targets: two years of success - target fabrication, irradiation and radioisotope production. Argentinean spent fuels: plans and projects - intermediate storing - final conditioning. (author)

[en] During 2004 several activities related to RERTR topics has taken place. In what follows, a resume of those activities is presented. During 2004 the Nuclear Fuel Cycle Program has supported the activities of about a hundred of researchers and technicians involved on different aspects of Very high density fuel developpement (VHD) fuel development as R and D, mini-plates, plates and fuel assemblies fabrication, irradiation and PIE analyses of VHD fuels. CNEA's LEU MTR fuel waste disposal plans are concerned with spent fuel from the reactor RA-3. The SF will be kept in interim storage until a geological repository is available for disposal. According to the current planning, this repository would be available in the year 2050 to receive the SF from the NPPs or the HLW from their reprocessing. Since 2002 the domestic production of Mo99 and other fission radioisotopes is performed using LEU targets, fulfilling international technical and quality standards. Up to present more than 600 targets bearing LEU material have been fabricated irradiated and processed. Very recently CNEA has also become an international supplier of targets for Mo-99 production. This status report deals as well with the International framework i.e. Global Threat Reduction Initiative and the historical involvement of Argentina in the peaceful applications of nuclear energy

[en] The known use of alumina as a separation step of ⁹⁹Mo in acid medium requires, for its proper accomplishment, the determination of both the type of alumina and the separation conditions. Utilization of LEU can involve changes in the nature of the targets and also in the dissolution method, which necessitates the eventual consideration of an acid medium for the attack. A study on molybdenum retention and elution in alumina was performed at laboratory scale, using '9⁹Mo radiotracer. Different kinds of alumina were tested for varying conditions (acidity, temperature and uranium concentration) of the loading solutions. The behaviour of uranium in this proposed separative stage was also studied. (author)

[en] The next generation of fission and fusion advanced nuclear systems will require materials capable of withstanding extreme conditions of temperature and radiation. Until now, several microcrystalline ceramics (grain dimension larger than 100 nm) have been studied intensely with regards to their radiation response while nanocrystalline materials (grain dimension smaller than 10 nm) in contrast have received relatively little attention. In the present work, the radiation response of different nanostructured films has been studied, including zirconia thin films that are both mesoporous and nanocrystalline with and without cerium incorporated. The film synthesis was carried out through the sol-gel technique and dip coating, followed by a thermal treatment. The films were characterized before and after irradiation using X-ray reflectometry (XRR), grazing incidence X-ray diffraction (GIXRD), low angle Xray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The mesoporous zirconia films were irradiated in the TANDAR accelerator of the Centro Atómico Constituyentes with ¹²⁷I⁺ ions of 132 - 180 keV and 70 MeV, and different fluences, the dpa being much larger for the lower ion energies. The zirconia films were composed of two crystalline phases, depending on the thermal treatment: monoclinic and tetragonal. It was observed that the iodine irradiation at low energies eliminated the monoclinic phase without significantly affecting the tetragonal phase. When Ce³⁺ was incorporated in the tetragonal zirconia phase the susceptibility to radiation damage was enhanced. This is presumably due to an increase in the number of vacancies arising from the substitution of Ce³⁺ for Zr⁴⁺. (author)