[en] This work presents the results of the assays carried out in the Laboratory of Hot Cells of the National Institute of Nuclear Research (ININ) to a type test tube Compact Tension (CT), built in steel austenitic stainless type 304L, simulating those conditions those that it operates a Boiling Water Reactor (BWR), at temperature 288 C and pressure of 8 MPa, to determine the speed to which the cracks spread in this material that is of the one that different components of a reactor are made, among those that it highlights the reactor core vessel. The application of the Hydrogen Chemistry of the Water is presented (HWC) that is one alternative to diminish the corrosion effect low stress in the component, this is gets controlling the quantity of oxygen and of hydrogen as well as the conductivity of the water. The rehearsal is made following the principles of the Mechanics of Elastic Lineal Fracture (LEFM) that considers a crack of defined size with little plastic deformation in the tip of this; the measurement of crack advance is continued with the technique of potential drop of direct current of alternating signal, this is contained inside the standard Astm E-647 (Method of Test Standard for the Measurement of Speed of Growth of Crack by fatigue) that is the one that indicates us as carrying out this test. The specifications that should complete the test tubes that are rehearsed as for their dimensions, it forms, finish and determination of mechanical properties (tenacity to the fracture mainly) they are contained inside the norm Astm E-399, the one which it is also based on the principles of the fracture mechanics. The obtained results were part of a database to be compared with those of other rehearsals under different conditions, Normal Chemistry of the Water (NWC) and it dilutes with high content of O₂; to determine the conditions that slow more the phenomena of stress corrosion cracking, as well as the effectiveness of the used chemistry and of the method of monitoring of crack growth. (Author)

[en] In the fusion plasma experiment TJ-II two neutral beam injectors (NBI) will provide 2 Mw heating power to the plasma, in each injector, a 100 a ion beam is generated at the duopigatron ion source, extracted and accelerated to 40 Kev in the grids, and subsequently neutralized at the neutralizer at each pulse, the high flow rate of H2 gas necessary to plasma formation and beam neutralization is injected at both ion source and neutralizer, and diffuses through the grids, beam box and duct. (Author)

[en] In this study the simulations of plasma transport under NBI for TJ-II, previously performed, are extended. Since than a considerable number of important modifications have been introduced in the model: change of magnetic configuration, use of experimental initial profiles, expansion of the Data base from NBI calculations and, mainly, a detailed handling of impurities with inclusion of sputtering effects. Moreover there is now a particular emphasis on the analysis of the conditions for discharge collapse and on the possible effects of single beam injection. This analysis of impurity behaviour with sputtering shows that in the expected usual cases there is no radioactive collapse and that if the recycling coefficients remain lower the unity it is always possible to find a strategy for external gas puffing leading to a stationary state, with densities below the limit and efficient NBI absorption (>50%). The radioactive collapse can appear either at high densities (central value higher than 1.4x10''20 m''3), excessive influx of impurities (i. e. with sputtering rates higher than twice the expected values) o for insufficient injected beam power (less than 45 kW). The present study analyses only the 100₄4₆4 configuration of TJ-II, but future works will start a systematic scan of configuration using this same model. (Author) 12 Refs

[en] The density and electron temperature radial profiles, corresponding to the experimental TJ-II campaigns 2003-2004, with NBI, have been fitted to simple functionals in order to allow a fast approximative evaluation for any given density and injected power... The fits have been calculated, separately, for the four possibilities: ECRH and NBI Phases as well as On and Off Axis ECRH injection. The average difference between the experimental profiles for the individual discharges and the fit predictions are around 8% for the density and 10% for the temperature. The behaviour of the predicted profiles with average line density and injected power has been analysed. The central electron temperature decreases monotonically with increasing density and the ECRH phase On Axis central value is clearly higher than the Off axis one. The radial density profiles narrow with increasing density and the NBI On axis case is clearly wider than de Off one. The electron temperature profile widens slightly with increasing density and the width of the On Axix case is lesser than for the Off case in all phases. There exist Fortran subroutines, available at the three CIEMAT computers, allowing the fast approximative evaluation of all these profiles. (Author) 8 refs

[en] In this study a numerical analysis of power loads on the complex 3D structure of the TJ-II Vacuum Vessel, moderated with reasonable accuracy, under NBI, is done. To do this it has been necessary to modify deeply the DENSB code for power loads in order to include the TJ-II VV wall parts as targets and as beam scrapers, allowing the possibility of self-shadowing. After a short description of the primitive version of the DENSB code (paragraph 2) and of the visualisation code MOVIE(paragraph 3), the DENSB upgrading are described (paragraphs 4,5) and finally the results are presented (paragraph 6). These code modifications and the improving on the visualization tools provide more realistic load evaluations, both with and without plasma, validating former results and showing clearly the VV zones that will need new protections. (Author)

[en] Calculations for NBI losses, absorption and power deposition radial profiles, corresponding to the experimental TJ-II campaigns 2003-2004, have been fitted to simple functionals in order to allow a fast approximative evaluation for any given density. The average difference between the calculations for the individual discharges using the experimental density and temperature radial profiles and the fit predictions are between 10 and 15% and the behaviour with density is the expected one: nonotonic decrease of shine through losses and increase of absorption with incipient saturation for high densities. The fast ion birth radial profile narrows initially at low densities but later starts to widen, although, for the average line density range analysed (0.51 a 4.1x10''13 cm''-3), never are wide enough to induce an increase of direct orbit losses neither to produce hollow radial profiles. The power absorption radial profile widens nonotonically. There exist Fortran subroutines, available at the three CIEMAT computers, allowing the fast approximative evaluation of all these values. (Author) 8 refs

[en] A systematic analysis of magnetic configurations (27 in total), using a Transport model including impurity dynamics and sputtering effects has been done. For small size configurations or those close to rational t values there is radioactive collapse, independently of the external gas puffing (GP) strategy chosen. The reason is the insufficiency of observed power, either by the high shine through losses due to their low radii, or by the increase of fast ion orbit losses near the resonances. For the majority of configurations without collapse, fast ion orbit losses for CO injection (going in the same direction than the toroidal magnetic field) are higher, and in consequence the power absorption and the plasma β achieved are laser, than for the opposite direction. Nevertheless in the region placed just above the main resonances (1/3 and 1/2 per period) this situation reverses. The reasons have been analysed and explained at previous studies. A consequence of this fact is that the optima of confinement for the Counter case are shifted towards higher t values than the CO one, with higher plasma β, except near the resonances. As usual the balanced case is in between. The optima achieving stationary state are very close (and often are coincident) with those lacking that restriction. The best configuration (highest average β for balanced injection, with <β>=1.1% and central value 3.2%, although in this region the results are rather insensitive to configuration and GP strategy. the configurations placed around the 100₄4 would need also the lowest power entering the torus in order to avoid collapse and to achieve an acceptable NBI absorption level. (Author) 12 refs

[en] Steam reforming of natural gas is a very important industrial process in refineries and ammonia and methanol plants. Hydrogen is produced by reforming methane with steam. This hydrogen is essential in the hydro-treating process in the refineries thus, it is important to supervise and control the performance of the hydrogen plant. Mathematical models of refineries and chemical plants are used to simulate the behavior of the process units. However, the models especially of reactors like reformers are not very reliable. This paper presents a dynamic model of a furnace-reactor. The simulation results are validated with industrial data

[en] The structure of fast ion losses in neutral beam moderation at TJ-II is analysed theoretically, in particular the influence of resonant effects and the radial electric field dependence. The direct losses show strong resonant effects when the ratio of the poloidal and toroidal rotation velocities pass near the values -4/3, -2 or 0. These effects are visible as strong maxima on the loss fractions and also as characteristic trajectory behaviours. The delayed losses present resonant effects also, generally at intermediate energies (5 to 20 KeV for 40 keV injection). Near the resonances the population of passing particles in these losses is very high and the loss fraction can equal or even surpass the direct losses. In these delayed losses the particles concentrate along vertical strips on the loss cone diagrams of roughly constant parallel velocity. This parallel velocity increases with the electric field, the loss maxima are reached usually when the pitch and energy of these strips are near the initial injection values. The trapped particle population in these delayed losses is maximal at null electric and decreases with the field intensity for both potential signs. The corresponding final energies are usually low (1 to 5 keV). Except at extreme potentials, where the -4 resonance can appear, no resonant effects are observed for this population. The resonance ordering is similar for all configurations and follows reasonably the predictions of a simple model. The extreme configurations are dominated by the effects of the 0 and -2 resonances, giving very high loss fractions even for null electric field. In contrast the intermediate configurations, near the Reference one, do not present resonant effects and the losses are moderate at low potentials. Only above 2000 v the resonant effects start to appear. (Author) 11 refs

[en] The sensibility of the Neutral Beam Injection system of TJ-II to the changes of several parameters is analysed. Transmission, absorption and power loads at the intercepting structures are evaluated. The adopted values for the ion source distance, focal length and divergence are confirmed as optimal, showing a small sensitivity to changes, except for the divergence. The operational margins for beam misalignments has been found to be small but feasible, confirming also the reference directions as optimal. Finally four possible alternatives, intended to reduce the power loads at the beam entering structures, are analysed. All of them have been discarded since lead to the appearance of new risk zones, with unacceptable load levels, and reduce the transmitted power. (Author) 13 refs