[en] One of the most modern methods to characterize the protective properties of coatings is the Electrochemical Impedance Spectroscopy (EIS). The EIS can provide useful information about transport of water and corrosive species through a coating. In this study, the impedance measurements were performed in different frequency ranges at open circuit potential for different coatings in 3 % NaCl. Two methods of data interpretation were considered: the break-point frequency method and the most probable equivalent circuit method (MPI). The interpretation of impedance spectra permitted the determination of water permeation, formation of blisters, swelling of the coating and the loss of adhesion including the delaminated area. (Author)

[en] Lithium aluminates proposed to the production of tritium in fusion nuclear reactors, due to the thermal stability that they present as well as the behavior of the aluminium to the irradiation. As a neutron flux with profile (≅ 14 Mev) of a fusion reactor is not available. A irradiation experiment was designed in order to know the micro and nano structure damages produced by fast and thermal neutrons in two irradiation positions of the fusion nuclear reactor Triga Mark III: CT (Thermal Column) and SIFCA (System of Irradiation Fixed of Capsules). In this work samples of lithium aluminate were characterized by XRD (X-Ray Diffraction), TEM (Transmission Electron Microscopy) and SEM (Scanning Electron Microscopy). Two samples were prepared by two methods: a) coalition method and b) peroxide method. This characterization comprised original and irradiated samples. The irradiated sample amounted to 4 in total: one for each preparation method and one for each irradiation position. The object of this analysis was to correlate with the received neutron dose the damages suffered by the samples with the neutron irradiation during long periods (440 H), in their micro and nano structure aspects; in order to understand the changes as a function of the irradiation zone (with thermal and fast neutron flux) and the preparation methods of the samples and having as an antecedent the irradiation in SIFCA position by short times (2h). The obtained results are referred to the stability of γ -aluminate phase, under given conditions of irradiation and defined nano structure arrangement. They also refer to the proposals of growth mechanism and nucleation of new phases. The error associated with the measurement of neutron dose is also discussed. (Author)

[en] In order to satisfy to the compromises derived of the ratification by part of the Mexican Government for the Nuclear Safety Convention it is presented this National Report which is based on the directives proposed as a result of the preparatory meetings held in the IAEA Headquarters in the city of Vienna, Austria. This National Report represents a document summary and activities realized at present in relation with the only nuclear facility in Mexico: the Nuclear Power Plant in Laguna Verde, Veracruz. This report consists of two parts: In the first one it is described how have been satisfied each one of the compromises. The second one talks about the Laws and Regulations on nuclear activities in the country. (Author)

[en] Food irradiation is increasingly accepted and applied in many countries in the past decade. Through its use, food losses and food-borne diseases can be reduced significantly, and wider trade in many food items can be facilitated. The past five decades have witnessed a positive evolution on food irradiation according to the following: 1940's: discovery of principles of food irradiation; 1950's: initiation of research in advanced countries; 1960's: research and development were intensified in some advanced and developing countries; 1970's: proof of wholesomeness of irradiated foods; 1980's: establishment of national regulations; 1990's: commercialization and international trade. (Author)

[en] The International Consultative Group on food Irradiation (ICGFI) was established in 1984 under the aegis of FAO, IAEA and WHO, following the adoption by the Codex Alimentarius Commission of the Codex General Standard for Irradiated foods and the Recommended International Code of Practice for the Operation of radiation Facilities for the treatment of food. Today, several countries from South America and the Caribbean have regular representatives in the ICGFI. Some of the countries also have regulations about food irradiation: Argentina, Brazil, Chile, Costa Rica, Cuba, Mexico, Peru and Uruguay. After a meeting in Peru in April 1997, Latin American countries agreed to attempt a harmonization of national laws according to an approved regional model regulation on irradiated food. The model legislation is based on the principles of the Codex General Standard for Irradiated Foods and Recommended Code of Practice for the Operation of Radiation Facilities Used for the Treatment of Foods, as well as on the relevant recommendations of the ICGFI. The model regulation establishes the authority, objectives, scope, definitions, general requirements, facilities, control procedures, documentation inspection, labeling and also provides and advisory technological dose limit by classes of food. (Author)

[en] Transfusion-associated graft-versus-host disease (TA-GVHD) is a usually complication of transfusion of blood component containing T lymphocytes what recently has also involved immunocompetent patient. Gamma irradiation of cellular blood components has been the mainstay against TA-GVHD, nevertheless there is little information in the literature about current transfusion medicine practices regarding gamma irradiation of blood products. This work presents an overview of the Brazilian reality and suggests policies to optimize TA-GVHD prevention. (Author)

[en] The objective of this work is in order to present in table formats the dosimetry of wires and single ribbons of Iridium with lengths 1-12 cm for each one linear source along the bisector which is perpendicular at tissue sources (water) computed for linear activity 1 mCi/cm in the case of wires, and 1 mCi/seed for ribbons. The above tables are of direct use, adaptable at particular cases so they facilitate logarithmic graphics of doses in function of the distance for interpolation and use in the treatments planning. It was shown that for two sources with identical linear activity and total length, one of the equidistant seeds at 1 cm (ribbon) and one wire on the other hand, the differences in dose rates in near positions can be about the 15% so corroborating that it is not possible to use wire tables for seeds neither vice versa. Moreover it was elaborated tables of practical direct use for dose rate in water at c Gy/hr for wires and Ribbons 1-12 cm length and from 0.5-10 cm of distance in the perpendicular bisector at the Iridium implant. (Author)

[en] This work come along of the necessity to utilize an unique High-Energy Electron Linear Accelerator (10 MV) for radiant treatments which require higher doses in the surface levels of tissue. It is analyzed the interposition of acrylic degraders (spoilers) in the beam, especially for opposed and parallel fields in the cases of head and neck. It was analyzed the possible combinations of the following parameters: 1) Field sizes defined at isocenter (100 cm) 6 x 6 cm², 8 x 8 cm² and 10 x 10 cm² ; 2) Surface-spoiler distance (DSS) of 4, 7 and 10 cm; 3) Spoilers with different thickness 1.1 and 1.5 cm. It was observed a displacement of the maximum dose toward the surface, and an increase in the percentile doses in the build-up zone when the spoiler is nearing and/or increasing its thickness. It is verified that the use of spoilers, support the symmetry and plane of the beam inside of the clinically acceptable margins. When the results obtained are analyzed then it is proposed as a calculation method to incorporate an attenuation factor. (Author)

[en] The objectives of this work are to present solutions adopted with the purpose to improve the technical quality of our treatments. It is described the ICRU-50 nomenclature employed in our department, the application of the linear quadratic radiobiological model for the non conventional division into fractions calculations and some proposals from diverse localizations. It is described some techniques for treatments planning, as the use of modulator fields and mobile gaps with hemi-fields. Also it is described some contrivances utilized, such as the shoulders tensor in head and neck tumors. The radiotherapeutic treatment with few sources it is optimized with the personnel effort and the low costs. (Author)

No abstract available