[en] The influence of the sample radius and irradiated zone width on the defocusing phenomenon is analysed by means of theoretical expressions which result from the convolution of a Cauchy fitting of the diffraction peak on the receiving plane. For the usual sample radius (about 12 mm) an irradiated zone width which is larger than expected may be used without any additional intensity loss. For a small sample radius (e.g. 4 mm), defocusing is less pronounced when a 6 mm irradiated zone width is used. (0002) and [10-10] pole figures of Zry-4 (a zirconium-based alloy) samples (obtained from a cladding tube of a pressurized water reactor fuel element) illustrate the results. (Auth.)

[en] The purpose of the present note is to report measurements of particle size and microstrains, by the Warren-Averbach method, in solid samples of Zircaloy-4 as a function of the degree of cold work. This zirconium alloy is principally used for the fuel cladding tubes of water-pressurized reactors. (Auth.)

[en] The theoretical fundaments of the Distribution Function of Crystalline Orientations (DFCO) are described and this method is compared with the usual description of the crystallographic texture by direct pole figures. Such function is applied to the study of a Zry-4 sample obtained from a tube belonging to a CANDU type fuel element. The DFCO is obtained from the pole figures (0002), (101-bar0) and (101-bar1). The results show the existence of six fundamental components of texture, which are enunciated below, in decreasing order of importance: (2-bar115) <101-bar0>; (3-bar128) <15-bar40>; (1-bar013) <12-bar10>; (2-bar114) <01-bar10>; (0001) <01-bar10>; (0001) <12-bar10>. A much more complete view of the crystals' orientation state of such sample can be obtained by analyzing the weight and the distribution of the different components. (M.E.L.)

[en] The crystallographic texture developed during the manufacturing of ZRY-4 cladding tubes has been extensively studied by Tenckhoff and Rittenhouse. The amount of activity of pyramidal slip in cold rolling of ZRY-4 is still a controversial point. For example, in a work by Pochettino et al. only the aforementioned twin systems and prismatic slip were taken into account to perform a simulation of the final (0002) pole figure, resulting from a cold rolling of a plate up to 50% thickness reduction. From a technological point of view, the knowledge about the amount of activity of pyramidal slip is of major importance, because, if it were large enough it would allow larger strain per step in order to reduce the number of intermediate annealings. The purpose of this work was to use the Orientation Distribution Function (ODF) to study in details the orientation changes of the crystallites, in order to reveal the operation of pyramidal slip

[en] The aim of this work is to determine the crystallographic orientations of austenite and the A laminar graphite and the compact, in one-directionally grown samples to decide upon the validity of the mentioned theory. (Author)

[en] The development of new low enrichment nuclear fuels for research and radioisotope production reactors imposes the knowledge of properties and behaviors about a series of alloys which the reducing of U²³⁵ (fissionable) concentration is compensated with a greater density of this element inside the fuel. One of these series is composed by U alloys with different contents of alloying, that allow to retain the body centered cubic structure solid solution recognized as phase α in metastable condition at low temperatures. For the present work 10 U based alloys were manufactured with different concentrations containing up to 43,7 % zirconium weight and up to 7,3 % niobium weight. An arch oven was utilized with argon atmosphere. The identification of the present phases in massive samples from the melting was carried out through X-rays diffraction analysis. The results obtained in this work are compared with others results published since the year 1957. In the samples melted the intermetallic UZr₂ diminishes in quantity with the reduction of the composition of Zr in the alloys. In all of them were identified, besides, Zr₆Fe₃O, ZrO_0,35, α and U₃O₈ present in quantities reduced. The quantity of the two last phases diminishes at the same time with the content in Zr. The parameter of network of the cubic phase γU in these alloys can be represented for the equation: α=(3,5796 -0,1616.x_Nb+0,1155.x_Zr)/(1.0306+0,003.x_Nb-0,0068.x_Zr. The parameter of network of the γ phase was measured. Comparing it measured with the value calculated, for eight alloys, the proposed equation showed a very good adjustment (HC)

[en] Since last RRFM meeting, CNEA (Argentina National Energy Commission) has continued on new LEU (low enrichment uranium) fuel and target development activities as a part of the national policy on minimization of the use of HEU (high enrichment uranium) on civilian applications. 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 (very high density) dispersed and monolithic fuels technical problems, to optimize techniques to recover U from silicide scrap samples as cold test for radioactive waste 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 non-destructive techniques to assess bonding quality; -) irradiation of mini-plates 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. (authors)

[en] When austenite is cooled or deformed, it may fail and transform phase ε(hcp) or suffer a martensitic transformation (bct). Three alloys prepared in the laboratory were studied so as to have the same amount of impurities within the AISI 304 normative and laminated with different liquid nitrogen reduction percentages. One of the solutions had hydrogen (H) introduced to it in solution. The solute influence on present phase concentration and the crystal structure were analyzed. (Author)

[en] Since last RERTR meeting, several tasks involving RERTR activities continued deploying in Argentina: through an agreement between CNEA and US-DoE final steps in the RA-6 reactor core conversion from HEU to LEU are taking place; by means of a return campaign of 42 US origin SNF in the frame of the US-SNF FRR program; an effective minimization of HEU inventory is close to be accomplished; development of a LEU dispersed U-Mo fuel prototype, to be irradiated in a high flux reactor in the frame of the ARG/4/092 IAEA's Technical Cooperation project is progressing; very high density monolithic U-Mo miniplates and plates using MEU and LEU fuel with Zry-4 cladding were developed to be irradiated as a part of the RERTR program irradiation experiment; atomistic modeling prediction (BFS techniques and first principles) enabled to find some trends on the interaction phases; diffusion couples tests under X-ray synchrotron analysis allowed the characterization of several phases involving U-Mo(-Zr) / Al(-Si); finally CNEA continued spreading high quality LEU technology for fission RI production by means of agreements with different producers interested on HEU-LEU conversion. (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)