http://hdl.handle.net/2117/3377 2013-05-25T01:17:41Z http://hdl.handle.net/2117/19009 Title: Experimental analysis of a degraded open-cathode PEM fuel cell stack Authors: Strahl, Stephan; Gasamans Rodríguez, Noemí; Llorca Piqué, Jordi; Husar, Attila Peter Abstract: The well-known challenges to be overcome in PEM fuel cell research are their relatively low durability and high costs for the platinum catalysts. Thus, this work focuses on factors that impact durability and the links to the fuel cell performance. Therefore a degraded, open-cathode, 20-cell, PEM fuel cell stack, which was used in a laboratory test station for characterization experiments, was analyzed experimentally. Voltage transients during external perturbations, such as changing temperature, humidity and stoichiometries show that degradation affects individual cells quite differently throughout the lifetime of the stack. Electrochemical impedance spectroscopy (EIS) data presents non-reversible catalyst layer and membrane degradation of several cells. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) are in progress in order to validate the results of the electrical analysis and elucidate catalyst and membrane degradation. 2013-04-26T12:04:59Z http://hdl.handle.net/2117/18722 Title: Present status and future programs of the n-TOF experiment Authors: Chiaveri, E.; Calviani, M.; Andriamonje, S.; Calviño Tavares, Francisco; Cortés Rossell, Guillem Pere; Riego Pérez, Albert; Gómez Hornillos, María Belén; Vlachoudis, V.; Massimi, C. Abstract: The neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology. The most relevant measurements performed up to now and foreseen for the future will be presented in this contribution. The overall efficiency of the experimental program and the range of possible measurements achievable with the construction of a second experimental area (EAR-2), vertically located 20 m on top of the n_TOF spallation target, might offer a substantial improvement in measurement sensitivities. A feasibility study of the possible realisation of the installation extension will be also presented. 2013-04-09T10:25:17Z http://hdl.handle.net/2117/18645 Title: Measurement of the Pu-240,242 neutron-induced fission cross sections Authors: Salvador-Castiñeria, P; Bevilacqua, R; Brys, T; Hambsch, FJ; Oberstedt, S; Pretel Sánchez, Carme; Vidali, M 2013-04-05T11:39:58Z http://hdl.handle.net/2117/18635 Title: Performance of the magnetic system of a 12 MeV UPC race-track microtron Authors: Koubychine Merkulov, Youri Alexandrovich; Rigla Perez, Juan Pablo; Shvedunov, V.I.; Pakhomov, N.I. Abstract: The per­for­mance of the mag­netic sys­tem of a 12 MeV elec­tron race-track mi­cro­tron (RTM) which is under con­struc­tion at the Uni­ver­si­tat Politècnica de Catalunya (UPC) is de­scribed. The RTM mag­netic sys­tem con­sists of two four-pole end mag­nets with the main field level about 0.8 T, one quadru­pole and four beam ex­trac­tion dipoles. As a source of the mag­netic field in these mag­nets a Sa-Co rare earth per­ma­nent mag­net ma­te­r­ial is used. This helps to get a quite com­pact de­sign of the RTM and al­lows to place the mag­netic sys­tems in a high vac­uum en­vi­ron­ment of the ac­cel­er­a­tor vac­uum cham­ber. We dis­cuss re­sults of nu­mer­i­cal sim­u­la­tions of the tun­ing of the end mag­nets by mean of spe­cial tuners and de­scribe their en­gi­neer­ing de­sign which per­mits to as­sem­ble the mag­nets and fix the Sa-Co blocks with­out glu­ing. Also a method and re­sults of mag­netic field dis­tri­b­u­tion mea­sure­ments and mag­net tun­ing are re­ported. 2013-04-05T10:03:10Z http://hdl.handle.net/2117/18205 Title: Diseño conceptual e ingenieria de detalle de un lazo experimental dual Pb15.7Li/ He (proyecto BCN_LOOP®): una propuesta de proyecto de I+D+i industrial para desarrollos clave en tecnologia nuclear de fusion Authors: Batet Miracle, Lluís; Reventós Puigjaner, Francesc Josep; Mas de les Valls Ortiz, Elisabet; Fernández, Iván; Veredas, G.; Abellà, Jordi; Sempere Cebrían, Julià; Sanmartí, Manel; Linares, José Ignacio; Sedano, L.A. 2013-03-12T12:24:21Z http://hdl.handle.net/2117/18170 Title: Análisis de la permeación de tritio en los canales de metal líquido de las envolturas regeneradoras de un reactor de fusión en presencia de burbujas de helio Authors: Batet Miracle, Lluís; Mas de les Valls Ortiz, Elisabet; Sedano, L.A. Abstract: En el interior de los canales de metal l quido de las envolturas regeneradoras de un reactor de fusi on, la posibilidad de existencia de burbujas de helio nucleado no es remota. El helio se forma junto al tritio en la reacci on de los neutrones escapados del plasma con el litio. La acumulaci on de helio en las super cies de contacto entre la estructura y el ML conllevar a una reducci on de la transferencia de calor, al mismo tiempo que una reducci on en la permeaci on de tritio. La coexistencia de tres fases en contacto: metal l quido, helio y material estructural, convierte al transporte de calor y tritio en fen omenos complejos. Para enriquecer estudios de transporte de tritio realizados en el pasado, se plantea ahora un an alisis de detalle del entorno de una burbuja de helio adherida a la pared de un canal de ML de una envoltura regeneradora. Para el estudio se ha utilizado una herramienta CFD desarrollada sobre el c odigo libre OpenFOAM. El transporte de tritio a trav es de las tres fases y a trav es de cada interfase se ha analizado de forma detallada mediante simulaci on CFD. El modelo incluye los distintos mecanismos de transporte: difusi on en ML y gas; recombinaci on y disociaci on en las interfases. Los resultados obtenidos deben permitir re nar los modelos simpli cados ya utilizados en el c alculo de transporte de tritio en canales de ML en presencia de helio nucleado en las paredes 2013-03-11T11:45:59Z http://hdl.handle.net/2117/18168 Title: Máster en Ingeniería Nuclear por la UPC (Máster UPC-ENDESA). Balance de la primera edición Authors: Batet Miracle, Lluís; Duch Guillen, María Amor; Calviño Tavares, Francisco; del Val, Luis; Fernández-Olano, Pablo Abstract: El Máster en Ingeniería Nuclear por la UPC, está orientado a la formación de ingenieros nucleares con un nivel alto de competencias que les permitan optar a puestos de responsabilidad en empresas del sector. El máster, que ha iniciado su andadura durante el curso 2011-2012, cuenta con el patrocinio de ENDESA y la colaboración de entidades y empresas del sector. En esta ponencia se realiza un balance de los dos primeros semestres del máster y se describen los puntos fuertes y las oportunidades de mejora detectados. En el análisis se ha tenido en cuenta el rendimiento académico de los estudiantes, sus impresiones y el grado de satisfacción. La información se ha recogido a través de encuestas, entrevistas personales y reuniones con todo el grupo de estudiantes. Los 90 créditos ECTS del Máster se reparten en asignaturas obligatorias (46,5) y optativas (13,5) y prácticas externas y Proyecto Final. La participación de expertos externos a la universidad ha sido muy alta (casi un 50 % de la docencia), especialmente en las materias de Gestión de Plantas y Normativa y Seguridad. Todas las materias incluyen actividades basadas en aprendizaje activo y trabajo en equipo: se consigue así que el sistema de evaluación sea una parte integral e inseparable del proceso de aprendizaje. En cada uno de los dos semestres lectivos, los estudiantes desarrollan un proyecto transversal en grupos de tres o cuatro miembros. En general el grado de satisfacción del alumnado es muy bueno, pero se han detectado algunos aspectos referentes a la distribución de la carga de trabajo y a los mecanismos de evaluación que han sido mejorados sobre la marcha. Estas mejoras se incorporarán en la edición de 2012-2013. Creemos que el Máster satisface las expectativas del sector y de la sociedad a la vez que presenta un gran atractivo para los estudiantes. 2013-03-11T11:18:50Z http://hdl.handle.net/2117/17758 Title: Comissioning of the decelerator test beam line in CTF3 Authors: Adli, E; Döbert, Steffan; Lillestol, R; Olvegaard, M; Syratchev, I; Carrillo, David; Toral, Fernando; Faus-Golfe, Angeles; García-Garrigos, JJ; Koubychine Merkulov, Youri Alexandrovich; Montoro López, Gabriel Abstract: The CLIC Test Facility (CTF3) at CERN was constructed by the CTF3 collaboration to study the feasibility of the concepts for a compact linear collider. The test beam line (TBL) recently added to the CTF3 machine was designed to study the CLIC decelerator beam dynamics and 12 GHz power production. The beam line consists of a FODO lattice with high precision BPM’s and quadrupoles on movers for precise beam alignment. A total of 16 Power Extraction and Transfer Structures (PETS) will be installed in between the quadrupoles to extract 12 GHz power from the drive beam provided by the CTF3 machine. The CTF3 drive beam with a bunchtrain length of 140 ns, 12 GHz bunch repetition frequency and an average current over the train of up to 28 A will be injected into the test beam line. Each PETS structure will produce 135 MW of 12 GHz power at nominal current. The beam will have lost more than 50 % of its initial energy of 150 MeV at the end of the beam line and will contain particles with energies between 65 MeV and 150 MeV. The beam line is completely installed and the PETS structures will be successively added until the end of 2011. The paper will describe the first results obtained during commissioning of the beam line and the first PETS prototype. 2013-02-14T11:52:46Z http://hdl.handle.net/2117/17656 Title: Current status of the 12 MeV UPC race-track microtron Authors: Koubychine Merkulov, Youri Alexandrovich; Berenguer Sau, Jordi; Crisol, A; Gonzalez, Xavier; Montoro López, Gabriel; Rigla Perez, Juan Pablo; Roure Fernández, Francisco; Carrillo, David; Garcia-Tabares, Luis; Toral, F; Lucas, J; Aloev, A.V.; Shvedunov, V.I. Abstract: A com­pact race-track mi­crotron (RTM) with the max­i­mal out­put en­er­gy 12 MeV is under con­struc­tion at the Uni­ver­si­tat Politècnica de Catalun­ya (UPC) in col­lab­o­ra­tion with the Sko­belt­syn In­sti­tute of Nu­cle­ar Physics of the Moscow State Uni­ver­si­ty, CIEMAT and a few Span­ish in­dus­tri­al com­pa­nies and med­i­cal cen­ters. The RTM end mag­nets are four-pole sys­tems with the mag­net­ic field cre­at­ed by a rare-earth per­ma­nent mag­net ma­te­ri­al. As a source of elec­trons a 3D off-ax­is elec­tron gun is used. These el­e­ments to­geth­er with a C-band ac­cel­er­at­ing struc­ture, dipole mag­nets, which allow to ex­tract the elec­tron beam with en­er­gy from 6 MeV to 12 MeV in 2 MeV step, and a fo­cus­ing quadrupole are placed in­side a vac­u­um cham­ber. We re­port on the cur­rent sta­tus of the tech­ni­cal de­sign and re­sults of tests of some of the com­po­nents. 2013-02-12T13:01:40Z http://hdl.handle.net/2117/17626 Title: Simulations of emittance measurement at CLIC Authors: Koubychine Merkulov, Youri Alexandrovich; Garcia, Hector; Marin Lacoma, Eduard; Schulte, Daniel; Stulle, Frank Abstract: A proposal for a CLIC emittance measurement line using laser-wire beam profile monitors is presented. Results of simulations and optimizations are given. Estimates of the impact of beam size as well as statistical and machinerelated errors on the measurement accuracy are discussed. 2013-02-11T12:18:12Z http://hdl.handle.net/2117/17623 Title: A novel electron gun for off-beam injection Authors: Koubychine Merkulov, Youri Alexandrovich; Aloev, A.V.; Shvedunov, V.I.; Pakhomov, N.I. Abstract: For certain type of electron accelerators injection from an off-axis cathode is required. This is the case of a racetrack microtron (RTM), in which the beam passes several times through the accelerating structure, or of a high power standing wave electron linac, for which the lifetime of an on-axis cathode would be strongly reduced by the electron back-bombardment. The standard solution with the beam injection via a dipole magnet from an electron gun placed off-axis is too bulky, moreover in case of RTMs it requires special compensating dipoles. An annular ring cathode gun used in some accelerators leads to large beam emittance and divergence. As a new solution we describe a 3D on-axis electron gun with an off-axis cathode and a central hole for the beam passage. Results of the design optimization and performance of an electron gun built for a miniature 12 MeV RTM for medical applications are presented. We also discuss results of the beam parameters measurements and estimates of the beam emittance. 2013-02-11T11:46:01Z http://hdl.handle.net/2117/17603 Title: RF and accelerating structure of 12 MeV UPC race-track microtron Authors: Koubychine Merkulov, Youri Alexandrovich; Gonzalez, Xavier; Montoro López, Gabriel; Carrillo, David; Garcia-Tabares, Luis; Toral, Fernando; Mathot, Serge Jean; Shvedunov, V.I. Abstract: We describe the design and technical characteristics of a C-band SW accelerating structure of a 12 MeV race-track microtron, which is under construction at the Technical University of Catalonia, and its RF system with a 5712 MHz magnetron as a source. Results of cold tests of the accelerating structure, before and after the brazing, and of high-power tests of the RF system at a special stand are reported. The main features of the magnetron frequency stabilization subsystem are also outlined. 2013-02-08T10:17:03Z http://hdl.handle.net/2117/17601 Title: Laser wire emittance measurement line at CLIC Authors: Garcia, Hector; Koubychine Merkulov, Youri Alexandrovich; Blair, Grahame; Aumeyr, T; Schulte, Daniel; Shvedunov, V.I. Abstract: A precise measurement of the transverse beam size and beam emittances upstream of the final focus is essential for ensuring the full luminosity at future linear colliders. A scheme for the emittance measurements at the RTML line of the CLIC using laser-wire beam profile monitors is described. A lattice of the measurement line is discussed and results of simulations of statistical errors and of their impact on the accuracy of the emittance reconstruction are given. Laser wire systems suitable for CLIC and their main characteristics are discussed. 2013-02-08T09:43:16Z http://hdl.handle.net/2117/17592 Title: Monte Carlo simulation of the total dose distribution around the 12 MeV UPC race-track microtron and radiation shielding calculations Authors: De la Fuente, Cristina; Duch Guillen, María Amor; Koubychine Merkulov, Youri Alexandrovich; Shvedunov, V.I. Abstract: The Technical University of Catalonia is building a miniature 12 MeV electron race-track microtron for medical applications. In the paper we study the leakage radiation caused by beam losses inside the accelerator head, as well as the bremsstrahlung radiation produced by the primary beam in the commissioning setting. Results of Monte Carlo simulations using the PENELOPE code are presented and two shielding schemes, global and local, are studied. The obtained shielding parameters are compared with estimates based on DIN 6847 part 2 as international recommendation of the radiation safety standards. 2013-02-07T12:33:21Z http://hdl.handle.net/2117/17348 Title: MHD para fusión: parámetros puente entre CFD y códigos de sistema Authors: Mas de les Valls Ortiz, Elisabet; Batet Miracle, Lluís; Sedano, L.A. 2013-01-14T15:16:51Z