An exactly soluble multiatom-multiphoton coupling model

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Response of L-alanine and 2-methylalanine minidosimeters for K-Band (24 GHz) EPR dosimetry

Minidosimeters of L-alanine and 2-methylalanine (2MA) were prepared and tested as potential candidates for small radiation field dosimetry. To quantify the free radicals created by radiation a K-Band (24 GHz) EPR spectrometer was used. X-rays provided by a 6 MV clinical linear accelerator were used to irradiate the minidosimeters in the dose range of 0.5-30 Gy. The dose-response curves for both radiation sensitive materials displayed a good linear behavior in the dose range indicated with 2MA being more radiation sensitive than L-alanine. Moreover, 2MA showed a smaller LLD (lower limit detection) value. The proposed system minidosimeter/K-Band spectrometer was able to detect 10 Gy EPR spectra with good signal-to-noise ratio (S/N). The overall uncertainty indicates that this system shows a good performance for the detection of dose values of 20 Gy and above, which are dose values typically used in radiosurgery treatments. (c) 2007 Elsevier B.V. All rights reserved.

Study of the effects of exposure to ionizing irradiation on the materials used for dental restoration

A quantitative study was made about the effects caused by ionizing irradiation on materials used for dental restoration (amalgams, compound resins and compomere), aiming to alleviate in bearers of head and neck cancer, the possible harmful effects of radiotherapy perceived when the repaired teething is within the radiation field. Research also encourages further studies for new alternative materials to be used in dental repair of patients submitted to radiotherapy for head and neck cancer. Test samples were submitted to a gamma radiation beam coming from a cobalt-therapy source and analyzed according to the X-ray fluorescence technique, comparing the chemical composition of the samples before and after irradiation. Radiation detectors such as an ionization chamber and a Geiger-Muller were used to measure the rate of residual dose. Gamma spectrometry with Nal detectors was also performed on the same samples. Results showed that there was no significant change in the chemical composition and that at post-irradiation, samples did not exhibit radiation emission, that is to say they had not become radioactive.

Global and diffuse solar irradiances in urban and rural areas in southeast Brazil

The seasonal evolution of daily and hourly values of global and diffuse solar radiation at the surface are compared for the cities of S��o Paulo and Botucatu, both located in Southeast Brazil and representative of urban and rural areas, respectively. The comparisons are based on measurements of global and diffuse solar irradiance carried out at the surface during a six year simultaneous period in these two cities. Despite the similar latitude and altitude, the seasonal evolution of daily values indicate that S��o Paulo receives, during clear sky days, 7.8% less global irradiance in August and 5.1% less in June than Botucatu. on the other hand, S��o Paulo receives, during clear sky days, 3.6% more diffuse irradiance in August and 15.6% more in June than Botucatu. The seasonal variation of the diurnal cycle confirms these differences and indicates that they are more pronounced during the afternoon. The regional differences are related to the distance from the Atlantic Ocean, systematic penetration of the sea breeze and daytime evolution of the particulate matter in S��o Paulo. An important mechanism controlling the spatial distribution of solar radiation, on a regional scale, is the sea breeze penetration in S��o Paulo, bringing moisture and maritime aerosol that in turn further increases the solar radiation scattering due to pollution and further reduces the intensity of the direct component of solar radiation at the surface. Surprisingly, under clear sky conditions the atmospheric attenuation of solar radiation in Botucatu during winter - the biomass burning period due to the sugar cane harvest - is equivalent to that at S��o Paulo City, indicating that the contamination during sugar cane harvest in Southeast Brazil has a large impact in the solar radiation field at the surface.

Deviation from the sech2 superradiant emission law in a two-level atomic system

The atomic superradiant emission is treated in the single-particle mean-field approximation. A single-particle Hamiltonian, which represents a dressed two-level atom in a radiation field, can be obtained and it is verified that it describes the transient regime of the emission process. While the line-shape emission for a bare atom follows the sech2 law, for the dressed atom the line shape deviates appreciably from this law and it is verified that the deviation depends crucially on the ratio of the dynamic frequency shift to the transition frequency. This kind of deviation is observed in experimental results. �� 1990 The American Physical Society.

Avalia����o da dose de radia����o absorvida em exames radiol��gicos durante o planejamento radioter��pico

P��s-gradua����o em Pesquisa e Desenvolvimento (Biotecnologia M��dica) - FMB

Observational effects of stellar rotation on Be stars' disks

Be stars are known to be fast rotators. At high rotation rates a profound modification of the radiation field reaching the circumstellar environment is expected. The origin of this modification is the decrease of the effective gravity on stellar surface leading to the stellar geometrical flattening and the gravity darkening effect predicted by Von Zeipel. Making use of the radiative transfer code HDUST we discuss the consequences of such stellar rotation on the structure of Be star disks based on the Viscous Decretion Disk model. Observational predictions are also made, as SED, IR-excess and Hydrogen line profiles. The modified illumination of the circumstellar disk generates significant changes in these quantities. Ascertaining these changes is useful to set some of the fundamental parameters of the Be system and to unveil the role of stellar rotation over the stellar evolution.

Entwicklung und Evaluierung einer Modellhierarchie zur Simulation der aktinischen Strahlung in aerosolbelasteter und bew��lkter Atmosph��re

Das Verstaendnis der in der Atmosphaere stattfindendenOzonproduktions- und Ozonabbaumechanismen ist eines derwichtigsten Ziele der aktuellen Umweltforschung. Da Ozon inder Atmosphaere ausschliesslich durch photochemischeProzesse gebildet wird, ist die Kenntnis der aktinischenStrahlung eine grundlegende Voraussetzung fuer die Prognosevon Ozonkonzentrationen. Die vorliegende Arbeit befasst sichdaher mit der Modellierung der aktinischen Strahlung alsBasis zur Untersuchung photochemischer Prozesse. Dazu wurde eine Modellhierarchie entwickelt, welcheausgehend von der Berechnung der optischen Eigenschaften deratmosphaerischen Extingenten den Strahlungstransport in derAtmosphaere bestimmt. Dazu wurden verschiedeneStrahlungstransportmodelle verwendet, welche sich durch dieLoesungsmethode der Strahlungstransportgleichung und dieAnzahl der raeumlichen Dimensionen unterscheiden. Zur Ueberpruefung der entwickelten Modellhierarchie und zurUntersuchung des Einflusses der verschiedenen Extingentenauf das atmosphaerische Strahlungsfeld wurden zahlreicheSensitivitaetsstudien durchgefuehrt. Dabei zeigte sich, dasssich der Einfluss von Ozon fast ausschliesslich auf denAnteil der Strahlung mit Wellenlaengen kleiner 340 nmauswirkt. Bei der Untersuchung des Einflusses vonAerosolpartikeln und Wolkentropfen auf die aktinischeStrahlung wurde festgestellt, dass die chemischeZusammensetzung, das Vertikalprofil, die Groesse und dieGroessenverteilung der Partikel einen entscheidendenEinfluss nehmen. Eine Evaluierung des 1-dimensionalenStrahlungstransportmodells an Hand von Vergleichen mit denErgebnissen anderen Strahlungstransportmodelle undverschiedenen Messungen ergab, dass die entwickelteModellhierarchie sehr zuverlaessige Resultate liefert. Die Effekte durchbrochener Bewoelkung konnten mit einer2-dimensionalen Simulation untersucht werden. DieUntersuchungen zeigen, dass die haeufig durchgefuehrteapproximative Betrachtung von partieller Bewoelkung mit1-dimensionalen Strahlungstransportmodellen im Vergleich zuden Ergebnissen der 2-dimensionalen Simulation grosse Fehlerverursacht, da die Effekte an den seitlichen Wolkenraendernvon den 1-dimensionalen Strahlungstransportmodellen nichtberuecksichtigt werden koennen.

Galactic fountain flows in high-resolution hydrodynamical simulations of galaxy disks

Feedback from the most massive components of a young stellar cluster deeply affects the surrounding ISM driving an expanding over-pressured hot gas cavity in it. In spiral galaxies these structures may have sufficient energy to break the disk and eject large amount of material into the halo. The cycling of this gas, which eventually will fall back onto the disk, is known as galactic fountains. We aim at better understanding the dynamics of such fountain flow in a Galactic context, frame the problem in a more dynamic environment possibly learning about its connection and regulation to the local driving mechanism and understand its role as a metal diffusion channel. The interaction of the fountain with a hot corona is hereby analyzed, trying to understand the properties and evolution of the extraplanar material. We perform high resolution hydrodynamical simulations with the moving-mesh code AREPO to model the multi-phase ISM of a Milky Way type galaxy. A non-equilibrium chemical network is included to self consistently follow the evolution of the main coolants of the ISM. Spiral arm perturbations in the potential are considered so that large molecular gas structures are able to dynamically form here, self shielded from the interstellar radiation field. We model the effect of SN feedback from a new-born stellar cluster inside such a giant molecular cloud, as the driving force of the fountain. Passive Lagrangian tracer particles are used in conjunction to the SN energy deposition to model and study diffusion of freshly synthesized metals. We find that both interactions with hot coronal gas and local ISM properties and motions are equally important in shaping the fountain. We notice a bimodal morphology where most of the ejected gas is in a cold $10^4$ K clumpy state while the majority of the affected volume is occupied by a hot diffuse medium. While only about 20\% of the produced metals stay local, most of them quickly diffuse through this hot regime to great scales.

Monte Carlo simulation of a dynamic MLC based on a multiple source model

Detailed knowledge of the characteristics of the radiation field shaped by a multileaf collimator (MLC) is essential in intensity modulated radiotherapy (IMRT). A previously developed multiple source model (MSM) for a 6 MV beam was extended to a 15 MV beam and supplemented with an accurate model of an 80-leaf dynamic MLC. Using the supplemented MSM and the MC code GEANT, lateral dose distributions were calculated in a water phantom and a portal water phantom. A field which is normally used for the validation of the step and shoot technique and a field from a realistic IMRT treatment plan delivered with dynamic MLC are investigated. To assess possible spectral changes caused by the modulation of beam intensity by an MLC, the energy spectra in five portal planes were calculated for moving slits of different widths. The extension of the MSM to 15 MV was validated by analysing energy fluences, depth doses and dose profiles. In addition, the MC-calculated primary energy spectrum was verified with an energy spectrum which was reconstructed from transmission measurements. MC-calculated dose profiles using the MSM for the step and shoot case and for the dynamic MLC case are in very good agreement with the measured data from film dosimetry. The investigation of a 13 cm wide field shows an increase in mean photon energy of up to 16% for the 0.25 cm slit compared to the open beam for 6 MV and of up to 6% for 15 MV, respectively. In conclusion, the MSM supplemented with the dynamic MLC has proven to be a powerful tool for investigational and benchmarking purposes or even for dose calculations in IMRT.

A randomized clinical trial of adjuvant chemotherapy for radically resected locoregional relapse of breast cancer: IBCSG 27-02, BIG 1-02, and NSABP B-37

In this phase III, multinational, randomized trial, the International Breast Cancer Study Group, Breast International Group, and the National Surgical Adjuvant Breast and Bowel Project will attempt to define the effectiveness of cytotoxic therapy for patients with locoregional recurrence of breast cancer. We will evaluate whether chemotherapy prolongs disease-free survival and, secondarily, whether its use improves overall survival and systemic disease-free survival. Quality of life measurements will be monitored during the first 12 months of the study. Women who have had a previous diagnosis of invasive breast cancer treated by mastectomy or breast-conserving surgery and who have undergone complete surgical excision of all macroscopic disease but who subsequently develop isolated local and/or regional ipsilateral invasive recurrence are eligible. Patients are randomized to observation/no adjuvant chemotherapy or to adjuvant chemotherapy; all suitable patients receive radiation, hormonal, and trastuzumab therapy. Radiation therapy is recommended for patients who have not received previous adjuvant radiation therapy but is required for those with microscopically positive margins. The radiation field must encompass the tumor bed plus a surrounding margin to a dose of >or= 40 Gy. Radiation therapy will be administered before, during, or after chemotherapy. All women with estrogen receptor-positive and/or progesterone receptor-positive recurrence must receive hormonal therapy, with the agent and duration to be determined by the patient's investigator. Adjuvant trastuzumab therapy is permitted for those with HER2- positive tumors, provided that intent to treat is declared before randomization. Although multidrug regimens are preferred, the agents, doses, and use of supportive therapy are at the discretion of the investigator.

The design and evaluation of a 2D dose verification system for intensity modulated radiotherapy

The usage of intensity modulated radiotherapy (IMRT) treatments necessitates a significant amount of patient-specific quality assurance (QA). This research has investigated the precision and accuracy of Kodak EDR2 film measurements for IMRT verifications, the use of comparisons between 2D dose calculations and measurements to improve treatment plan beam models, and the dosimetric impact of delivery errors. New measurement techniques and software were developed and used clinically at M. D. Anderson Cancer Center. The software implemented two new dose comparison parameters, the 2D normalized agreement test (NAT) and the scalar NAT index. A single-film calibration technique using multileaf collimator (MLC) delivery was developed. EDR2 film's optical density response was found to be sensitive to several factors: radiation time, length of time between exposure and processing, and phantom material. Precision of EDR2 film measurements was found to be better than 1%. For IMRT verification, EDR2 film measurements agreed with ion chamber results to 2%/2mm accuracy for single-beam fluence map verifications and to 5%/2mm for transverse plane measurements of complete plan dose distributions. The same system was used to quantitatively optimize the radiation field offset and MLC transmission beam modeling parameters for Varian MLCs. While scalar dose comparison metrics can work well for optimization purposes, the influence of external parameters on the dose discrepancies must be minimized. The ability of 2D verifications to detect delivery errors was tested with simulated data. The dosimetric characteristics of delivery errors were compared to patient-specific clinical IMRT verifications. For the clinical verifications, the NAT index and percent of pixels failing the gamma index were exponentially distributed and dependent upon the measurement phantom but not the treatment site. Delivery errors affecting all beams in the treatment plan were flagged by the NAT index, although delivery errors impacting only one beam could not be differentiated from routine clinical verification discrepancies. Clinical use of this system will flag outliers, allow physicists to examine their causes, and perhaps improve the level of agreement between radiation dose distribution measurements and calculations. The principles used to design and evaluate this system are extensible to future multidimensional dose measurements and comparisons. ^

BSRN snapshot 2015-09, links to zip archives

The Baseline Surface Radiation Network (BSRN) and its central archive - the World Radiation Monitoring Center (WRMC) - was created in 1992. It is a project of the Data Assimilation Panel from the Global Energy and Water Cycle Experiment (GEWEX) under the umbrella of the World Climate Research Programme (WCRP) and as such is aimed at detecting important changes in the Earth's radiation field at the Earth's surface which may be related to climate changes. The data are of primary importance in supporting the validation and confirmation of satellite and computer model estimates of these quantities. At a small number of stations in contrasting climatic zones, covering a latitude range from 80��N to 90��S, solar and atmospheric radiation is measured with instruments of the highest available accuracy and with high time resolution (1 to 3 minutes). Since 2008 the WRMC is hosted by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), Bremerhaven, Germany (http://www.bsrn.awi.de/).

Conformaci��n de Superficies Reflectoras de Sistemas Dobles de Tipo Offset con Alimentadores descritos en Campo Pr��ximo

This work discusses an iterative procedure of shaping offset dual-reflector antennas based on geometrical optics considering both far-field and near-field measurements of amplitude and phase from the feed horn. The surfaces synthesized will transform a known radiation field of a feed to a desired aperture distribution. This technique is applied for both circular and elliptical apertures and has the advantage to simplify the problem compared with existing techniques based on solving nonlinear differential equations. A MATLAB tool has been developed to implement the shaping algorithms. This procedure is applied for the design of a 1.1 m high-gain antenna for the ESA���s Solar Orbiter spacecraft. This antenna operating at X-band will manage high data rate and high efficiency communications with Earth stations.

Dise��o de un m��dulo de IFMIF para irradiaci��n de envolturas regeneradoras basadas en metales l��quidos para reactores de fusi��n

La fusi��n nuclear es, hoy en d��a, una alternativa energ��tica a la que la comunidad internacional dedica mucho esfuerzo. El objetivo es el de generar entre diez y cincuenta veces m��s energ��a que la que consume mediante reacciones de fusi��n que se producir��n en una mezcla de deuterio (D) y tritio (T) en forma de plasma a doscientos millones de grados cent��grados. En los futuros reactores nucleares de fusi��n ser�� necesario producir el tritio utilizado como combustible en el propio reactor termonuclear. Este hecho supone dar un paso m��s que las actuales m��quinas experimentales dedicadas fundamentalmente al estudio de la f��sica del plasma. As�� pues, el tritio, en un reactor de fusi��n, se produce en sus envolturas regeneradoras cuya misi��n fundamental es la de blindaje neutr��nico, producir y recuperar tritio (fuel para la reacci��n DT del plasma) y por ��ltimo convertir la energ��a de los neutrones en calor. Existen diferentes conceptos de envolturas que pueden ser s��lidas o l��quidas. Las primeras se basan en cer��micas de litio (Li2O, Li4SiO4, Li2TiO3, Li2ZrO3) y multiplicadores neutr��nicos de Be, necesarios para conseguir la cantidad adecuada de tritio. Los segundos se basan en el uso de metales l��quidos o sales fundidas (Li, LiPb, FLIBE, FLINABE) con multiplicadores neutr��nicos de Be o el propio Pb en el caso de LiPb. Los materiales estructurales pasan por aceros ferr��tico-martens��ticos de baja activaci��n, aleaciones de vanadio o incluso SiCf/SiC. Cada uno de los diferentes conceptos de envoltura tendr�� una problem��tica asociada que se estudiar�� en el reactor experimental ITER (del ingl��s, ���International Thermonuclear Experimental Reactor���). Sin embargo, ITER no puede responder las cuestiones asociadas al da��o de materiales y el efecto de la radiaci��n neutr��nica en las diferentes funciones de las envolturas regeneradoras. Como referencia, la primera pared de un reactor de fusi��n de 4000MW recibir��a 30 dpa/a��o (valores para Fe-56) mientras que en ITER se conseguir��an <10 dpa en toda su vida ��til. Esta tesis se encuadra en el acuerdo bilateral entre Europa y Jap��n denominado ���Broader Approach Agreement ���(BA) (2007-2017) en el cual Espa��a juega un papel destacable. Estos proyectos, complementarios con ITER, son el acelerador para pruebas de materiales IFMIF (del ingl��s, ���International Fusion Materials Irradiation Facility���) y el dispositivo de fusi��n JT-60SA. As��, los efectos de la irradiaci��n de materiales en materiales candidatos para reactores de fusi��n se estudiar��n en IFMIF. El objetivo de esta tesis es el dise��o de un m��dulo de IFMIF para irradiaci��n de envolturas regeneradoras basadas en metales l��quidos para reactores de fusi��n. El m��dulo se llamar�� LBVM (del ingl��s, ���Liquid Breeder Validation Module���). La propuesta surge de la necesidad de irradiar materiales funcionales para envolturas regeneradoras l��quidas para reactores de fusi��n debido a que el dise��o conceptual de IFMIF no contaba con esta utilidad. Con objeto de analizar la viabilidad de la presente propuesta, se han realizado c��lculos neutr��nicos para evaluar la idoneidad de llevar a cabo experimentos relacionados con envolturas l��quidas en IFMIF. As��, se han considerado diferentes candidatos a materiales funcionales de envolturas regeneradoras: Fe (base de los materiales estructurales), SiC (material candidato para los FCI��s (del ingl��s, ���Flow Channel Inserts���) en una envoltura regeneradora l��quida, SiO2 (candidato para recubrimientos antipermeaci��n), CaO (candidato para recubrimientos aislantes), Al2O3 (candidato para recubrimientos antipermeaci��n y aislantes) y AlN (material candidato para recubrimientos aislantes). En cada uno de estos materiales se han calculado los par��metros de irradiaci��n m��s significativos (dpa, H/dpa y He/dpa) en diferentes posiciones de IFMIF. Estos valores se han comparado con los esperados en la primera pared y en la zona regeneradora de tritio de un reactor de fusi��n. Para ello se ha elegido un reactor tipo HCLL (del ingl��s, ���Helium Cooled Lithium Lead���) por tratarse de uno de los m��s prometedores. Adem��s, los valores tambi��n se han comparado con los que se obtendr��an en un reactor r��pido de fisi��n puesto que la mayor��a de las irradiaciones actuales se hacen en reactores de este tipo. Como conclusi��n al an��lisis de viabilidad, se puede decir que los materiales funcionales para mantos regeneradores l��quidos podr��an probarse en la zona de medio flujo de IFMIF donde se obtendr��an ratios de H/dpa y He/dpa muy parecidos a los esperados en las zonas m��s irradiadas de un reactor de fusi��n. Adem��s, con el objetivo de ajustar todav��a m��s los valores, se propone el uso de un moderador de W (a considerar en algunas campa��as de irradiaci��n solamente debido a que su uso hace que los valores de dpa totales disminuyan). Los valores obtenidos para un reactor de fisi��n refuerzan la idea de la necesidad del LBVM, ya que los valores obtenidos de H/dpa y He/dpa son muy inferiores a los esperados en fusi��n y, por lo tanto, no representativos. Una vez demostrada la idoneidad de IFMIF para irradiar envolturas regeneradoras l��quidas, y del estudio de la problem��tica asociada a las envolturas l��quidas, tambi��n incluida en esta tesis, se proponen tres tipos de experimentos diferentes como base de dise��o del LBVM. ��stos se orientan en las necesidades de un reactor tipo HCLL aunque a lo largo de la tesis se discute la aplicabilidad para otros reactores e incluso se proponen experimentos adicionales. As��, la capacidad experimental del m��dulo estar��a centrada en el estudio del comportamiento de litio plomo, permeaci��n de tritio, corrosi��n y compatibilidad de materiales. Para cada uno de los experimentos se propone un esquema experimental, se definen las condiciones necesarias en el m��dulo y la instrumentaci��n requerida para controlar y diagnosticar las c��psulas experimentales. Para llevar a cabo los experimentos propuestos se propone el LBVM, ubicado en la zona de medio flujo de IFMIF, en su celda caliente, y con capacidad para 16 c��psulas experimentales. Cada c��psula (24-22 mm de di��metro y 80 mm de altura) contendr�� la aleaci��n eut��ctica LiPb (hasta 50 mm de la altura de la c��psula) en contacto con diferentes muestras de materiales. ��sta ir�� soportada en el interior de tubos de acero por los que circular�� un gas de purga (He), necesario para arrastrar el tritio generado en el eut��ctico y permeado a trav��s de las paredes de las c��psulas (continuamente, durante irradiaci��n). Estos tubos, a su vez, se instalar��n en una carcasa tambi��n de acero que proporcionar�� soporte y refrigeraci��n tanto a los tubos como a sus c��psulas experimentales interiores. El m��dulo, en su conjunto, permitir�� la extracci��n de las se��ales experimentales y el gas de purga. As��, a trav��s de la estaci��n de medida de tritio y el sistema de control, se obtendr��n los datos experimentales para su an��lisis y extracci��n de conclusiones experimentales. Adem��s del an��lisis de datos experimentales, algunas de estas se��ales tendr��n una funci��n de seguridad y por tanto jugar��n un papel primordial en la operaci��n del m��dulo. Para el correcto funcionamiento de las c��psulas y poder controlar su temperatura, cada c��psula se equipar�� con un calentador el��ctrico y por tanto el m��dulo requerir�� tambi��n ser conectado a la alimentaci��n el��ctrica. El dise��o del m��dulo y su l��gica de operaci��n se describe en detalle en esta tesis. La justificaci��n t��cnica de cada una de las partes que componen el m��dulo se ha realizado con soporte de c��lculos de transporte de tritio, termohidr��ulicos y mec��nicos. Una de las principales conclusiones de los c��lculos de transporte de tritio es que es perfectamente viable medir el tritio permeado en las c��psulas mediante c��maras de ionizaci��n y contadores proporcionales comerciales, con sensibilidades en el orden de 10-9 Bq/m3. Los resultados son aplicables a todos los experimentos, incluso si son c��psulas a bajas temperaturas o si llevan recubrimientos antipermeaci��n. Desde un punto de vista de seguridad, el conocimiento de la cantidad de tritio que est�� siendo transportada con el gas de purga puede ser usado para detectar de ciertos problemas que puedan estar sucediendo en el m��dulo como por ejemplo, la rotura de una c��psula. Adem��s, es necesario conocer el balance de tritio de la instalaci��n. Las p��rdidas esperadas el refrigerante y la celda caliente de IFMIF se pueden considerar despreciables para condiciones normales de funcionamiento. Los c��lculos termohidr��ulicos se han realizado con el objetivo de optimizar el dise��o de las c��psulas experimentales y el LBVM de manera que se pueda cumplir el principal requisito del m��dulo que es llevar a cabo los experimentos a temperaturas comprendidas entre 300-550��C. Para ello, se ha dimensionado la refrigeraci��n necesaria del m��dulo y evaluado la geometr��a de las c��psulas, tubos experimentales y la zona experimental del contenedor. Como consecuencia de los an��lisis realizados, se han elegido c��psulas y tubos cil��ndricos instalados en compartimentos cil��ndricos debido a su buen comportamiento mec��nico (las tensiones debidas a la presi��n de los fluidos se ven reducidas significativamente con una geometr��a cil��ndrica en lugar de prism��tica) y t��rmico (uniformidad de temperatura en las paredes de los tubos y c��psulas). Se han obtenido campos de presi��n, temperatura y velocidad en diferentes zonas cr��ticas del m��dulo concluyendo que la presente propuesta es factible. Cabe destacar que el uso de c��digos fluidodin��micos (e.g. ANSYS-CFX, utilizado en esta tesis) para el dise��o de c��psulas experimentales de IFMIF no es directo. La raz��n de ello es que los modelos de turbulencia tienden a subestimar la temperatura de pared en mini canales de helio sometidos a altos flujos de calor debido al cambio de las propiedades del fluido cerca de la pared. Los diferentes modelos de turbulencia presentes en dicho c��digo han tenido que ser estudiados con detalle y validados con resultados experimentales. El modelo SST (del ingl��s, ���Shear Stress Transport Model���) para turbulencia en transici��n ha sido identificado como adecuado para simular el comportamiento del helio de refrigeraci��n y la temperatura en las paredes de las c��psulas experimentales. Con la geometr��a propuesta y los valores principales de refrigeraci��n y purga definidos, se ha analizado el comportamiento mec��nico de cada uno de los tubos experimentales que contendr�� el m��dulo. Los resultados de tensiones obtenidos, han sido comparados con los valores m��ximos recomendados en c��digos de dise��o estructural como el SDC-IC (del ingl��s, ���Structural Design Criteria for ITER Components���) para as�� evaluar el grado de protecci��n contra el colapso pl��stico. La conclusi��n del estudio muestra que la propuesta es mec��nicamente robusta. El LBVM implica el uso de metales l��quidos y la generaci��n de tritio adem��s del riesgo asociado a la activaci��n neutr��nica. Por ello, se han estudiado los riesgos asociados al uso de metales l��quidos y el tritio. Adem��s, se ha incluido una evaluaci��n preliminar de los riesgos radiol��gicos asociados a la activaci��n de materiales y el calor residual en el m��dulo despu��s de la irradiaci��n as�� como un escenario de p��rdida de refrigerante. Los riesgos asociados al m��dulo de naturaleza convencional est��n asociados al manejo de metales l��quidos cuyas reacciones con aire o agua se asocian con emisi��n de aerosoles y probabilidad de fuego. De entre los riesgos nucleares destacan la generaci��n de gases radiactivos como el tritio u otros radiois��topos vol��tiles como el Po-210. No se espera que el m��dulo suponga un impacto medioambiental asociado a posibles escapes. Sin embargo, es necesario un manejo adecuado tanto de las c��psulas experimentales como del m��dulo contenedor as�� como de las l��neas de purga durante operaci��n. Despu��s de un d��a de despu��s de la parada, tras un a��o de irradiaci��n, tendremos una dosis de contacto de 7000 Sv/h en la zona experimental del contenedor, 2300 Sv/h en la c��psula y 25 Sv/h en el LiPb. El uso por lo tanto de manipulaci��n remota est�� previsto para el manejo del m��dulo irradiado. Por ��ltimo, en esta tesis se ha estudiado tambi��n las posibilidades existentes para la fabricaci��n del m��dulo. De entre las t��cnicas propuestas, destacan la electroerosi��n, soldaduras por haz de electrones o por soldadura l��ser. Las bases para el dise��o final del LBVM han sido pues establecidas en el marco de este trabajo y han sido incluidas en el dise��o intermedio de IFMIF, que ser�� desarrollado en el futuro, como parte del dise��o final de la instalaci��n IFMIF. ABSTRACT Nuclear fusion is, today, an alternative energy source to which the international community devotes a great effort. The goal is to generate 10 to 50 times more energy than the input power by means of fusion reactions that occur in deuterium (D) and tritium (T) plasma at two hundred million degrees Celsius. In the future commercial reactors it will be necessary to breed the tritium used as fuel in situ, by the reactor itself. This constitutes a step further from current experimental machines dedicated mainly to the study of the plasma physics. Therefore, tritium, in fusion reactors, will be produced in the so-called breeder blankets whose primary mission is to provide neutron shielding, produce and recover tritium and convert the neutron energy into heat. There are different concepts of breeding blankets that can be separated into two main categories: solids or liquids. The former are based on ceramics containing lithium as Li2O , Li4SiO4 , Li2TiO3 , Li2ZrO3 and Be, used as a neutron multiplier, required to achieve the required amount of tritium. The liquid concepts are based on molten salts or liquid metals as pure Li, LiPb, FLIBE or FLINABE. These blankets use, as neutron multipliers, Be or Pb (in the case of the concepts based on LiPb). Proposed structural materials comprise various options, always with low activation characteristics, as low activation ferritic-martensitic steels, vanadium alloys or even SiCf/SiC. Each concept of breeding blanket has specific challenges that will be studied in the experimental reactor ITER (International Thermonuclear Experimental Reactor). However, ITER cannot answer questions associated to material damage and the effect of neutron radiation in the different breeding blankets functions and performance. As a reference, the first wall of a fusion reactor of 4000 MW will receive about 30 dpa / year (values for Fe-56) , while values expected in ITER would be <10 dpa in its entire lifetime. Consequently, the irradiation effects on candidate materials for fusion reactors will be studied in IFMIF (International Fusion Material Irradiation Facility). This thesis fits in the framework of the bilateral agreement among Europe and Japan which is called ���Broader Approach Agreement ���(BA) (2007-2017) where Spain plays a key role. These projects, complementary to ITER, are mainly IFMIF and the fusion facility JT-60SA. The purpose of this thesis is the design of an irradiation module to test candidate materials for breeding blankets in IFMIF, the so-called Liquid Breeder Validation Module (LBVM). This proposal is born from the fact that this option was not considered in the conceptual design of the facility. As a first step, in order to study the feasibility of this proposal, neutronic calculations have been performed to estimate irradiation parameters in different materials foreseen for liquid breeding blankets. Various functional materials were considered: Fe (base of structural materials), SiC (candidate material for flow channel inserts, SiO2 (candidate for antipermeation coatings), CaO (candidate for insulating coatings), Al2O3 (candidate for antipermeation and insulating coatings) and AlN (candidate for insulation coating material). For each material, the most significant irradiation parameters have been calculated (dpa, H/dpa and He/dpa) in different positions of IFMIF. These values were compared to those expected in the first wall and breeding zone of a fusion reactor. For this exercise, a HCLL (Helium Cooled Lithium Lead) type was selected as it is one of the most promising options. In addition, estimated values were also compared with those obtained in a fast fission reactor since most of existing irradiations have been made in these installations. The main conclusion of this study is that the medium flux area of IFMIF offers a good irradiation environment to irradiate functional materials for liquid breeding blankets. The obtained ratios of H/dpa and He/dpa are very similar to those expected in the most irradiated areas of a fusion reactor. Moreover, with the aim of bringing the values further close, the use of a W moderator is proposed to be used only in some experimental campaigns (as obviously, the total amount of dpa decreases). The values of ratios obtained for a fission reactor, much lower than in a fusion reactor, reinforce the need of LBVM for IFMIF. Having demonstrated the suitability of IFMIF to irradiate functional materials for liquid breeding blankets, and an analysis of the main problems associated to each type of liquid breeding blanket, also presented in this thesis, three different experiments are proposed as basis for the design of the LBVM. These experiments are dedicated to the needs of a blanket HCLL type although the applicability of the module for other blankets is also discussed. Therefore, the experimental capability of the module is focused on the study of the behavior of the eutectic alloy LiPb, tritium permeation, corrosion and material compatibility. For each of the experiments proposed an experimental scheme is given explaining the different module conditions and defining the required instrumentation to control and monitor the experimental capsules. In order to carry out the proposed experiments, the LBVM is proposed, located in the medium flux area of the IFMIF hot cell, with capability of up to 16 experimental capsules. Each capsule (24-22 mm of diameter, 80 mm high) will contain the eutectic allow LiPb (up to 50 mm of capsule high) in contact with different material specimens. They will be supported inside rigs or steel pipes. Helium will be used as purge gas, to sweep the tritium generated in the eutectic and permeated through the capsule walls (continuously, during irradiation). These tubes, will be installed in a steel container providing support and cooling for the tubes and hence the inner experimental capsules. The experimental data will consist of on line monitoring signals and the analysis of purge gas by the tritium measurement station. In addition to the experimental signals, the module will produce signals having a safety function and therefore playing a major role in the operation of the module. For an adequate operation of the capsules and to control its temperature, each capsule will be equipped with an electrical heater so the module will to be connected to an electrical power supply. The technical justification behind the dimensioning of each of these parts forming the module is presented supported by tritium transport calculations, thermalhydraulic and structural analysis. One of the main conclusions of the tritium transport calculations is that the measure of the permeated tritium is perfectly achievable by commercial ionization chambers and proportional counters with sensitivity of 10-9 Bq/m3. The results are applicable to all experiments, even to low temperature capsules or to the ones using antipermeation coatings. From a safety point of view, the knowledge of the amount of tritium being swept by the purge gas is a clear indicator of certain problems that may be occurring in the module such a capsule rupture. In addition, the tritium balance in the installation should be known. Losses of purge gas permeated into the refrigerant and the hot cell itself through the container have been assessed concluding that they are negligible for normal operation. Thermal hydraulic calculations were performed in order to optimize the design of experimental capsules and LBVM to fulfill one of the main requirements of the module: to perform experiments at uniform temperatures between 300-550��C. The necessary cooling of the module and the geometry of the capsules, rigs and testing area of the container were dimensioned. As a result of the analyses, cylindrical capsules and rigs in cylindrical compartments were selected because of their good mechanical behavior (stresses due to fluid pressure are reduced significantly with a cylindrical shape rather than prismatic) and thermal (temperature uniformity in the walls of the tubes and capsules). Fields of pressure, temperature and velocity in different critical areas of the module were obtained concluding that the proposal is feasible. It is important to mention that the use of fluid dynamic codes as ANSYS-CFX (used in this thesis) for designing experimental capsules for IFMIF is not direct. The reason for this is that, under strongly heated helium mini channels, turbulence models tend to underestimate the wall temperature because of the change of helium properties near the wall. Therefore, the different code turbulence models had to be studied in detail and validated against experimental results. ANSYS-CFX SST (Shear Stress Transport Model) for transitional turbulence model has been identified among many others as the suitable one for modeling the cooling helium and the temperature on the walls of experimental capsules. Once the geometry and the main purge and cooling parameters have been defined, the mechanical behavior of each experimental tube or rig including capsules is analyzed. Resulting stresses are compared with the maximum values recommended by applicable structural design codes such as the SDC- IC (Structural Design Criteria for ITER Components) in order to assess the degree of protection against plastic collapse. The conclusion shows that the proposal is mechanically robust. The LBVM involves the use of liquid metals, tritium and the risk associated with neutron activation. The risks related with the handling of liquid metals and tritium are studied in this thesis. In addition, the radiological risks associated with the activation of materials in the module and the residual heat after irradiation are evaluated, including a scenario of loss of coolant. Among the identified conventional risks associated with the module highlights the handling of liquid metals which reactions with water or air are accompanied by the emission of aerosols and fire probability. Regarding the nuclear risks, the generation of radioactive gases such as tritium or volatile radioisotopes such as Po-210 is the main hazard to be considered. An environmental impact associated to possible releases is not expected. Nevertheless, an appropriate handling of capsules, experimental tubes, and container including purge lines is required. After one day after shutdown and one year of irradiation, the experimental area of the module will present a contact dose rate of about 7000 Sv/h, 2300 Sv/h in the experimental capsules and 25 Sv/h in the LiPb. Therefore, the use of remote handling is envisaged for the irradiated module. Finally, the different possibilities for the module manufacturing have been studied. Among the proposed techniques highlights the electro discharge machining, brazing, electron beam welding or laser welding. The bases for the final design of the LBVM have been included in the framework of the this work and included in the intermediate design report of IFMIF which will be developed in future, as part of the IFMIF facility final design.