Fernando Sordo - Academia.edu (original) (raw)

Papers by Fernando Sordo

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2013

ABSTRACT This paper reports on design studies concerning a moderator concept which aims to maximi... more ABSTRACT This paper reports on design studies concerning a moderator concept which aims to maximize the time averaged flux. The idea is to provide neutron spectra showing two clear maxima, with peaks at View the MathML source and View the MathML source arising from leakage from both cryogenic and thermal moderators. Such a concept known as a bi-spectral moderator (Mezei, 2006 [1]) while proven on a reactor source has only been examined for the ESS 2003 proposal. Filges et al. (2003 [2]), which featured a different design than the current ESS. This paper thus reports on a baseline design for such a moderator concept and shows that it can provide substantial gains in count rates for those applications not requiring high resolution in time-of-flight.

ABSTRACT The mechanical aspects of an extended vertical shaft rotating target have been evaluated... more ABSTRACT The mechanical aspects of an extended vertical shaft rotating target have been evaluated in a full-scale mockup test. A prototype assembly based on a conceptual target design for a 1 to 3-MW spallation facility was built and tested. Key elements of the drive/coupling assembly implemented in the prototype include high integrity dynamic face seals, commercially available bearings, realistic manufacturing tolerances, effective monitoring and controls, and fail-safe shutdown features. A representative target disk suspended on a 3.5 meter prototypical shaft was coupled with the drive to complete the mechanical tests. After1800 hours of operation the test program has confirmed the overall mechanical feasibility of the extended vertical shaft rotating target concept. Precision alignment of the suspended target disk; successful containment of the water and verification of operational stability over the full speed range of 30 to 60 rpm were primary indications the proposed mechanical design is valid for use in a high power target station.

Physics Procedia, 2012

ABSTRACT The ESS-Bilbao Accelerator Center site at Lejoa UPV/EHU campus will be provided with a p... more ABSTRACT The ESS-Bilbao Accelerator Center site at Lejoa UPV/EHU campus will be provided with a proton accelerator up to 300-400 MeV. In the first construction phase, a beam extraction will be set at the end of the DTL, which will produce a 50 MeV proton beam with an average current of 2.25 mA and 1.5 ms pulses at a frequency of 20 Hz. These beam characteristics allow to configure a low intensity neutron source based on Be (p, n) reactions, which enables experimentation with cold neutrons similar to that of LENS. The total beam power will be 112 kW, so the configuration of the neutron production target will be based on a rotating disk of beryllium slabs facing the beam on one side and a cryogenic methane moderator on the other, with the target-moderator system surrounded by a beryllium reflector. In this paper, first estimates will be presented for thermomechanical conditions of the target cooling scheme, neutron source intensities, and cold neutron pulses.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2015

Ion irradiation on dielectric materials produces several processes, such ionization and defect fo... more Ion irradiation on dielectric materials produces several processes, such ionization and defect formation followed by a decay governed by thermal processes such as heat diffusion and atomic rearrangement. Finally in the irradiated region the mechanical properties are altered, strain and stress fields appear, a densification takes places and other properties such as the refractive index are affected.

Nuclear Engineering and Design, 2009

High performance neutrón sources are being proposed for many scientific and industrial applicatio... more High performance neutrón sources are being proposed for many scientific and industrial applications, ranging from material studies, hybrid reactors and transmutation of nuclear wastes. In the case of transmutation of nuclear wastes, accelerator driven systems (ADS) are considered as one of the main technical options for such purpose. In ADS a high performance spallation neutrón source becomes an essential element for its operation and control. This spallation source must fulfil very challenging nuclear and thermo-mechanical requirements, because of the high neutrón rates needed in ADS. The material selection for this key component becomes of paramount importance, particularly the source window that separates the vacuum accelerator tube from the spallation material where the accelerated protons impinge. In this paper, an integral analysis of spallation sources is done, taking as a reference the projects in this field proposal in the framework of European projects. Our analysis and calculations show that titanium and vanadium alloys are more suitable than steel as structural material for an industrial ADS beam window, mostly due to its irradiation damage resistance.

Journal of Physics: Conference Series, 2011

The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been c... more The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been completed and the normal conducting section of the linac is at present under construction. The machine has been designed to be compliant with ESS specifications following the international guidelines of such project as described in Ref.

Journal of Physics: Conference Series, 2008

Energy Conversion and Management, 2008

The spallation process is a cascade of nuclear reactions induced by medium-energy hadrons, notabl... more The spallation process is a cascade of nuclear reactions induced by medium-energy hadrons, notably protons, which impinge in a suitable material as accelerated particles. A main outcome of that cascade is a shower of medium and high-energy neutrons, which can be used for irradiation purposes or to feed a subcritical reactor. The neutron production is accompanied by the generation of a broad set of radioactive products, which presents specific problems of radiological protection and decay heat removal. The nominal heat load is another point of concern, because of the very high power densities produced in the proton beam energy deposition in the interaction region. All these phenomena are taken into account in this paper in order to set up an integral and coherent task flowchart in order to guide the design of spallation sources.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2013

ABSTRACT This paper reports on design studies concerning a moderator concept which aims to maximi... more ABSTRACT This paper reports on design studies concerning a moderator concept which aims to maximize the time averaged flux. The idea is to provide neutron spectra showing two clear maxima, with peaks at View the MathML source and View the MathML source arising from leakage from both cryogenic and thermal moderators. Such a concept known as a bi-spectral moderator (Mezei, 2006 [1]) while proven on a reactor source has only been examined for the ESS 2003 proposal. Filges et al. (2003 [2]), which featured a different design than the current ESS. This paper thus reports on a baseline design for such a moderator concept and shows that it can provide substantial gains in count rates for those applications not requiring high resolution in time-of-flight.

ABSTRACT The mechanical aspects of an extended vertical shaft rotating target have been evaluated... more ABSTRACT The mechanical aspects of an extended vertical shaft rotating target have been evaluated in a full-scale mockup test. A prototype assembly based on a conceptual target design for a 1 to 3-MW spallation facility was built and tested. Key elements of the drive/coupling assembly implemented in the prototype include high integrity dynamic face seals, commercially available bearings, realistic manufacturing tolerances, effective monitoring and controls, and fail-safe shutdown features. A representative target disk suspended on a 3.5 meter prototypical shaft was coupled with the drive to complete the mechanical tests. After1800 hours of operation the test program has confirmed the overall mechanical feasibility of the extended vertical shaft rotating target concept. Precision alignment of the suspended target disk; successful containment of the water and verification of operational stability over the full speed range of 30 to 60 rpm were primary indications the proposed mechanical design is valid for use in a high power target station.

Physics Procedia, 2012

ABSTRACT The ESS-Bilbao Accelerator Center site at Lejoa UPV/EHU campus will be provided with a p... more ABSTRACT The ESS-Bilbao Accelerator Center site at Lejoa UPV/EHU campus will be provided with a proton accelerator up to 300-400 MeV. In the first construction phase, a beam extraction will be set at the end of the DTL, which will produce a 50 MeV proton beam with an average current of 2.25 mA and 1.5 ms pulses at a frequency of 20 Hz. These beam characteristics allow to configure a low intensity neutron source based on Be (p, n) reactions, which enables experimentation with cold neutrons similar to that of LENS. The total beam power will be 112 kW, so the configuration of the neutron production target will be based on a rotating disk of beryllium slabs facing the beam on one side and a cryogenic methane moderator on the other, with the target-moderator system surrounded by a beryllium reflector. In this paper, first estimates will be presented for thermomechanical conditions of the target cooling scheme, neutron source intensities, and cold neutron pulses.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2015

Ion irradiation on dielectric materials produces several processes, such ionization and defect fo... more Ion irradiation on dielectric materials produces several processes, such ionization and defect formation followed by a decay governed by thermal processes such as heat diffusion and atomic rearrangement. Finally in the irradiated region the mechanical properties are altered, strain and stress fields appear, a densification takes places and other properties such as the refractive index are affected.

Nuclear Engineering and Design, 2009

High performance neutrón sources are being proposed for many scientific and industrial applicatio... more High performance neutrón sources are being proposed for many scientific and industrial applications, ranging from material studies, hybrid reactors and transmutation of nuclear wastes. In the case of transmutation of nuclear wastes, accelerator driven systems (ADS) are considered as one of the main technical options for such purpose. In ADS a high performance spallation neutrón source becomes an essential element for its operation and control. This spallation source must fulfil very challenging nuclear and thermo-mechanical requirements, because of the high neutrón rates needed in ADS. The material selection for this key component becomes of paramount importance, particularly the source window that separates the vacuum accelerator tube from the spallation material where the accelerated protons impinge. In this paper, an integral analysis of spallation sources is done, taking as a reference the projects in this field proposal in the framework of European projects. Our analysis and calculations show that titanium and vanadium alloys are more suitable than steel as structural material for an industrial ADS beam window, mostly due to its irradiation damage resistance.

Journal of Physics: Conference Series, 2011

The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been c... more The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been completed and the normal conducting section of the linac is at present under construction. The machine has been designed to be compliant with ESS specifications following the international guidelines of such project as described in Ref.

Journal of Physics: Conference Series, 2008

Energy Conversion and Management, 2008

The spallation process is a cascade of nuclear reactions induced by medium-energy hadrons, notabl... more The spallation process is a cascade of nuclear reactions induced by medium-energy hadrons, notably protons, which impinge in a suitable material as accelerated particles. A main outcome of that cascade is a shower of medium and high-energy neutrons, which can be used for irradiation purposes or to feed a subcritical reactor. The neutron production is accompanied by the generation of a broad set of radioactive products, which presents specific problems of radiological protection and decay heat removal. The nominal heat load is another point of concern, because of the very high power densities produced in the proton beam energy deposition in the interaction region. All these phenomena are taken into account in this paper in order to set up an integral and coherent task flowchart in order to guide the design of spallation sources.