[en] The repair/maintenance of the CNA-1 QK-01 Moderator Cooler will be a leading case of the repair of a class 1 nuclear component in a high radiation environment; utilizing for the work, sophisticated remotely operated equipment. This paper describes the component, the repair-maintenance objective, and the equipment-procedures developed for the intervention. (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] U-Mo dispersed fuel can not fulfill the U density requirements for high flux reactors. Besides, in-pile experiments have shown a large interaction between the fuel particles and the matrix. Replacing dispersed fuel by an U-Mo foil has been proposed and is currently under investigation as a possible solution to these problems. Friction stir welding is being experimented at ANL to fabricate fuel plates. Supported by the ENDE-CAC-CNEA experience in FSW, experiments have been started. Successful weld were obtained between aluminum and stainless steels (as subrogate material instead U-Mo) which allowed the selection of optimum parameters. This were applied to encase stainless steel and U-Mo foils in aluminum plates. The first objective was the implementation of the process, optimization of operative parameters and selection of the adequated tests to qualify the welding. The second objective was to apply these technic to fabricate U-Mo /Al alloys diffusion couples. First results are presented. (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] 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] Full text: U-Mo dispersed fuel can not fulfil the U density requirements for high flux reactors. Besides, in pile experiments have shown a high degree of interaction between the fuel particles and the matrix generating large porosity. Replacing dispersed fuel by an U-Mo foil has been proposed and is being investigated as a possible solution to these problems. Friction stir welding (FSW) is being experimented at ANL to fabricate fuel plates. Supported by the ENDE-CAC-CNEA large experience in FSW, experiments have been started. Successful weldings have been obtained between Al and stainless steels as subrogate material instead U-Mo. The first objective is the implementation of the process, optimization of operative parameters and selection of the adequate tests to qualify the welding. The second objective is encase U-Mo foil in Al to be used as diffusion couples. (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] Out of reactor interdiffusion experiments between U-Mo alloys and Al alloys made close to fuel operation temperature are needed to validate the results obtained above 500 deg. C. A study of interdiffusion between U-Mo and Al or Al alloys, out and in reactor, has been initiated. The objective is to characterize the interdiffusion layer around 250 deg. C and study the influence of neutron irradiation. Irradiation experiments will be performed in the Argentine RA3 reactor and chemical diffusion couples will be fabricated by Friction Stir Welding (FSW) technique. In this work out-of-pile diffusion experiments performed at 340 deg. C are presented. Friction Stir Welding (FSW) was used to fabricate some of the samples. One of the results is the presence of Si, in the interaction layer, coming from the Al alloy. This is promising in the sense that the absence of Al rich phases may also be expected at low temperature. (author)