[en] The code DELFIN has been implemented for the solution of the neutrons diffusion equations in two dimensions obtained by applying the approximation of several groups of energy. The code works with any number of groups and regions, and can be applied to thermal reactors as well as fast reactor. Providing it with the diffusion coefficients, the effective sections and the fission spectrum we obtain the results for the systems multiplying constant and the flows of each groups. The code was established using the method of finite elements, which is a form of resolution of the variational formulation of the equations applying the Ritz-Galerkin method with continuous polynomial functions by parts, in one case of the Lagrange type with rectangular geometry and up to the third grade. The obtained results and the comparison with the results in the literature, permit to reach the conclusion that it is convenient, to use the rectangular elements in all the cases where the geometry permits it, and demonstrate also that the finite elements method is better than the finite differences method. (author)

[en] After almost a quarter of century of the accident happened in the nuclear plant of the Three Miles Island (TMI), they continue being published studies that analyze the effects in the population's health that lived in the surroundings of the plant. In this work a review of the studies but outstanding carried out to the date is made, considering with certain detail the made suppositions, the methods used and the obtained results. Since some studies contradict those suppositions, methods and results of the other ones, we seek to make one impartial and objective evaluation of all the analyses to obtain coherent conclusions and without bias. The underlying concepts to the epidemiological studies were revised, making emphasis in those that can introduce some bias. The models that exist on the effect in the health of the population of low dose were also revised. It was also revised the published correspondence in the scientific literature among the different authors, analyzing the different arguments, to decide which are those of more validity. A very important factor at this time is that a lapse has elapsed sufficiently appropriate as to think that the probability of changes in the tendencies of observed cancer diseases it changes. In our analyses it was tried to take into account that the suppositions and methodologies used in the studies were supported by those facts that can be checked by the existent registrations to the date and not by anecdotes or preconceived ideas. Lastly the conclusions of this work of review and analysis are presented. (Author)

[en] The Mexican society has a modest knowledge of the nuclear energy, even at the participant students of superior education level in this survey is finds a scarce compression with regard to their obtaining, use and manage. As a result of the lack of interest of the same society and at the problems that know each other like they are: the pollutants that it produces those nuclear waste and the possible use or warlike end, a fear is believed about this energy type. In the Superior School of Physics and Mathematics there is the possibility to make studies so much at master degree level in the one fear of the nuclear energy and the applications of the same one in peaceful uses. However, particularly the studies at master level seem to be immersed in a crisis that requires of different supports to be resolved. For all it previous was thought in carrying out a survey inside a student population with superior level to know the opinion and the knowledge on the nuclear energy in Mexico. In this work the results of the survey are analyzed with the purpose of to determine which is the knowledge of the community mentioned regarding the other energy types, the impact that they have these in the environment, the sustenance of the same ones and in particular on knowledge about the nuclear energy considering the aspects before mentioned. With base had said analysis settles down that the interviewed community knows very little about the nuclear energy but they show interest to study and to obtain bigger information about the same one, for what is very important to diffuse but and better information on the nuclear energy to the population's strata, because it is of supposing that the rest of the population has erroneous information on the nuclear energy. In particular for the community of the Superior School of Physics and Mathematics the diffusion of all the benefits of the peaceful applications of the nuclear energy, including the capacity to generate enormous quantities and energy that allow to have electricity, heat, seawater purification and hydrogen generation, it should be a challenge and a goal to complete. It is also required the support of the whole mexican nuclear community, the future depends on it. (Author)

[en] In this work we will try to show that nuclear energy can contribute to the generation energy in the present and the future, considering that its effect on the climatic change is relatively low and that the fuels that uses are available a large scale. At the moment it is had already commercial thermal fission reactors , there are also them of fast fission that allow the fuel rearing, although these last ones in much smaller number, with both types of fission nuclear reactors can be obtained a very important contribution to the generation of energy at world-wide level during the time that is necessary so that it is developed, constructs and operates the first commercial fusion reactor. The energy that is generated in the present and future must come from different sources, which require to be reliable, to have little effect on the environment, to have wide reserves of fuels and to be viable from an economic and social point of view, they must be viable and safe. Between possible alternative energies it is counted on the lot, the wind one, the geothermal one, originating of the tides and some others. An energy that must be considered so that it has arrived at his maturity and he is already able to contribute widely to cover the present needs and future it is nuclear energy, as much the originating one of the fission of a heavy centre like obtained when fusing two light centers. On base in the nuclear fuel reserves at world-wide level a simple calculation takes control of the lapse in which energy by means of the nuclear fission in rearing can be generated reactors expresses demonstrating that the time sufficient to finish to the investigation and development of fusion reactors which they generate energy in economic, safe and reliable form. Combining these two options the nuclear energy can be considered the future like for the present and the future with practically null effects in the climatic change. (Author)

[en] Presently work a Technical Specification of Improved Operation (ETOM) based on risk, proposal and already adopted by some nuclear power stations in the USA is analyzed. This ETOM is the CLO 3.0.9 Operation Limit Condition, concerning to unavailability of barriers, the corresponding analysis that includes deterministic and probabilistic considerations and it is superficially discussed their eventual application to the Laguna Verde Nucleo electric Central (CNLV). The impact in the risk of the proposed changes to the Operation Technical Specification (ETO) it was evaluated following a treatment of three roads recommended by the regulatory guide RG 1.177. It consisted of a simplified analysis of demarcation of the consequent risk with the lack of specific models of risk for this case on each power station, which don't include models of flaw of such passive structures as they are these barriers. Together with the results of the risk evaluation, it is also evaluated the impact on the defense in depth of adding the CLO 3.0.9 proposal to the ETO. With base in the integrated evaluation it was concluded that the change proposed to ETO carries insignificant increases of risk. Certainly, this conclusion is certain without considering any credit for the removal of undesirable potential consequences associated with the current conservative treatment of barriers. With the purpose of to identify and to justify the late times to enter to the actions corresponding to the supported equipment associated with the unavailable barriers, it was presented a change proposal with an analysis informed in risk using Probabilistic Risk Analysis methods (APR), combined with deterministic arguments and of defense in depth. The proposal of the licensees includes the NEI 04-08 guide providing detailed guide on the evaluation and handling of risk associated with the unavailability barriers, the above mentioned according to the 1.174 and 1.177 Regulatory guides. The evaluation procedure of the bench mark of risk previously described, it was developed for a range of base values of core damage frequency (CDF) of the power station and for a range of values of the importance for the CDF of the equipment that should be protected by the barrier in question (RAW), to have this way a sensitivity analysis. It was used an allowed out time maximum of 30 days. Possibly this CLO 3.0.9 can be applied in the CNLV when finishing the current process to implement the ETOM and provided it is fulfilled the requirements of the approval process by part of the CNSNS. (Author)

[en] In 1992 were emitted the changes officially at the 10CFR20 related with changes that had been made to the Publication 26 of the ICRP in 1977. In this work the changes are discussed and like they affected to the Manual of Calculation of Dose outside of the Site (ODCM) and to the Technical Specifications of Operation (ETOs) of the nuclear power plants with Water cooled reactors. With relationship to the ODCM, this it is a document that contains a description of the methodology and necessary parameters for the calculation of the concentrations and dose to the public resultants of the liquid and gaseous radiological discharges emitted in the diverse liberation points toward the atmosphere, in this work the effect of the changes in the 10CFR20 is mentioned on the ODCM. With regard to the ETOs, they were revised and they compared the previous and new versions of the 10CFR20 and it was analysed like they affect the ETOs those changes, concluding that the biggest effect is on the ETO corresponding to concentrations of radioactive material in liquid effluents. (Author)

[en] The systematic measurement of the isotopic composition of precipitation in various meteorological stations has shown the spatial and temporal complexity of ¹⁸O and ²H content distribution, which characterize the study area of the East Pacific Coast, as well as the rest of the areas sampled in the country. In various stations it was observed over several months that the isotopic effects of altitude and distance to the coast were contrary to expectations. The use of isotope techniques on the right hand side of the Tempisque river has enabled confirmation of the significant interaction which exists between ground-and surface waters. The presence of waters strongly evaporated in the aquifer indicates the preferential infiltration of surface waters in some sectors. The dynamics of these systems should be considered for the future development of the area, especially to evaluate the impact of infiltration of the presently contaminated water of the river Tempisque. (author). 7 refs, 10 figs, 3 tabs

[en] This paper presents the development of tools to facilitate the management so much, the operational monitoring of boiling water reactors (BWR) of the nuclear power plant of Laguna Verde (NPP-LV) through independent codes, and how to carry out the static calculations corresponding to process of optimized pre-design of the reference cycle next to current cycle. The progress and preliminary results obtained with the program SACal, developed at Instituto Nacional de Investigaciones Nucleares (ININ), central tool to achieve provide a management platform of the operational monitoring and pre-design of NPP-LV cycle are also described. The reached preliminary advances directed to get an Analysis center and automated design of fuel assembly cells are also presented, which together with centers or similar modules related with the fuel reloads form the key part to meet the targets set for the realization of a Management Platform of Nuclear Fuel of the NPP-LV. (Author)

[en] Results are presented from a 5-year experiment using ¹⁵N-enriched fertilizer to determine N₂ fixation in four tree species on degraded soils in a Mediterranean-climate region of central Chile in which there are 5 months of drought. Species tested included three slow-growing but long-lived savannah trees native to southers South America, (acacia caven, Prosopic alba and P. chilensis; Mimosoideae), and Tagasaste (Chamaecytisus proliferus ssp. palmensis; Papilonoideae), a fast-growing but medium-lived tree from the Canary Islands. Tagasaste produced four- to twenty-fold more biomass than the other species, but showed declining N₂ fixation and biomass accumulation during the 5th year, corresponding to the juvenile-to-adult developmental transition. Nitrogen content was significantly higher in Tagasaste and Acacia caven than in the other species. The data revealed inter-specific differences in resource allocation and phenology of N₂ fixation rarely detailed for woody plants in dryland regions. (author)

[en] We report line broadening in the 77 K ⁵⁷Fe Mössbauer spectra of some commercially available medicines based on ferrous sulfates and on ferrous fumarates. While introducing only a single ferrous doublet is required to fit the RT spectra of all samples, on the contrary the line shapes of the 77 K spectra are properly described with two ferrous doublets. We discuss eight different static and dynamic hypotheses as possible physical origins for these two doublets, but finally we propose that the reasons are similar for the ferrous sulfates and for the ferrous fumarates containing medicines, and it can be due to the presence of easily dehydrated and hydrated ferrous compounds. The presence of several hydrated sulfates was confirmed by RT Raman spectroscopy. Possible implications of these results related with the hydrated character by which the active parts of the medicines are fabricated by the pharmaceutical companies are also discussed.