B. Schillinger - Academia.edu (original) (raw)

Papers by B. Schillinger

5th International Topical Meeting on Neutron Radiography

Neutron Radiography - WCNR-11, 2020

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licens... more Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under license by Materials Research Forum LLC.

Zirconium in the Nuclear Industry: 18th International Symposium, 2018

Physics Procedia, 2017

In parallel to the upgrade of neutron imaging facility at TRR-1/M1 since 2015, the practice on im... more In parallel to the upgrade of neutron imaging facility at TRR-1/M1 since 2015, the practice on image processing software has led to implementation of neutron tomography (NT). The current setup provides a thermal neutron flux of 1.08×10 6 cm-2 sec-1 at the exposure position. In general, the sample was fixed on a plate at the top of rotary stage controlled by Labview 2009 Version 9.0.1. The incremental step can be adjusted from 0.45 to 7.2 degree. A 16 bit CCD camera assembled with a Nikkor 50 mm f/1.2 lens was used to record light from 6 LiF/ZnS (green) neutron converter screen. The exposure time for each shot was 60 seconds, resulting in the acquisition time of approximately three hours for completely turning the sample around. Afterwards, the batch of two dimensional neutron images of the sample was read into the reconstruction and visualization software Octopus reconstruction 8.8 and Octopus visualization 2.0, respectively. The results revealed that the system alignment is important. Maintaining the stability of heavy sample at every particular angle of rotation is important. Previous alignment showed instability of the supporting plane while tilting the sample. This study showed that the sample stage should be replaced. Even though the NT is a lengthy process and involves large data processing, it offers an opportunity to better understand features of an object in more details than with neutron radiography. The digital NT also allows us to separate inner features that appear superpositioned in radiography by cross-sectioning the 3D data set of an object without destruction. As a result, NT is a significant tool for revealing hidden information included in the inner structure of cultural heritage objects, providing great benefits in archaeological study, conservation process and authenticity investigating.

Physics Procedia, 2015

The University of California, Davis McClellan Nuclear Research Center (MNRC) operates a 2 MW TRIG... more The University of California, Davis McClellan Nuclear Research Center (MNRC) operates a 2 MW TRIGA TM reactor, which is currently the highest power TRIGA TM reactor in the United States. The Center was originally build by the US Air Force to detect hidden defects in aircraft structures using neutron radiography; the Center can accommodate samples as large as 10.00 m long, 3.65 m high, and weighing up to 2,270 kg. The MNRC reactor can be pulsed to 350 MW for about 30 ms (FWHM). The combination of a short neutron pulse with a fast microchannel plate based neutron detector enables high-resolution flash neutron radiography to complement conventional neutron radiography

The application of 3D computed tomography with X-rays and neutrons to visualize archaeological objects in blocks of soil

Studies in Conservation, 2010

Abstract The examination of archaeological objects lifted in blocks of soil is very time-consumin... more Abstract The examination of archaeological objects lifted in blocks of soil is very time-consuming; both this fact and the array of findings make it imperative to find new techniques of analysis and documentation to ensure archaeological interpretation. Computed tomography of such blocks of soil could be a non-destructive alternative to conventional methods. In the present study, the use of 3D computed tomography with X-rays (XCT) and neutrons (NCT) was reviewed and compared with conventional radiography and the manual unearthing and documentation of the objects. In almost every case it was possible to resolve all relevant archaeological questions by XCT. In some special cases it was not possible to visualize all organic materials. In contrast to XCT, NCT, which is very sensitive to hydrogen, visualizes organic materials much better than X-rays. On the other hand the high water content in the plaster and soil around the objects caused some problems because of this sensitivity to hydrogen. However, very good results were obtained with NCT when applied to already separated single metal objects with organic remains on their surface.

7th International Topical Meeting on Neutron Radiography (Itmnr-7), 2013

Imaging an intact, commercial battery as it cycles and wears is proved possible with neutron imag... more Imaging an intact, commercial battery as it cycles and wears is proved possible with neutron imaging. The wavelength range of imaging neutrons corresponds nicely with crystallographic dimensions of the electrochemically active species and the metal electrodes are relatively transparent. The time scale of charge/discharge cycling is well matched to dynamic tomography as performed with a golden ratio based projection angle ordering. The hydrogen content does create scatter which tends to blur internal structure. In this report, three neutron experiments will be described: 3D images of charged and discharged batteries were obtained with monochromatic neutrons at the FRM II reactor. 2D images (PSI) of fresh and worn batteries as a function of charge state may show a new wear pattern. In situ neutron diffraction (SNS) of the intact battery provides more information about the concentrations of electrochemical species within the battery as a function of charge state and wear. The combination of 2D imaging, 3D imaging, and diffraction data show how neutron imaging can contribute to battery development and wear monitoring.

Journal of Neutron Research, 2008

Even the most powerful steady-state neutron sources do not deliver sufficient flux for neutron im... more Even the most powerful steady-state neutron sources do not deliver sufficient flux for neutron imaging with microsecond time resolution. The future pulsed neutron spallation sources will offer a much higher peak flux, but have a low repetition rate that makes sequential data collection and synchronization for repetitive motions rather difficult. This paper proposes an asynchronous data collection scheme for recording movies of fast continuous repetitive motions like running combustion engines.

Neutronen sehen, was Röntgenstrahlen verborgen bleibt

D. B. Dingwell, Y. Lavallée, K.-U. Hess, A. Flaws, J. Marti, A. R. L. Nichols, H. A. Gilg, and B.... more D. B. Dingwell, Y. Lavallée, K.-U. Hess, A. Flaws, J. Marti, A. R. L. Nichols, H. A. Gilg, and B. Schillinger Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Theresienstr. 41/III, 80333 München, Germany Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, UK Consejo Superior de Investigations Cientificas, Institute of Earth Sciences Jaume Almera, Barcelona, Spain Research and Development Center for Ocean Drilling Science, Japan Agency for Marine Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan Ingenieursfakultät Bau Geo Umwelt, Technische Universität München, München, Germany Forschungsreaktor FRM-II, Technische Universität München, Garching, Germany

Neutron Tomography

Neutron Scattering in Novel Materials, 2000

Neutron imaging of a commercial Li-ion battery during discharge: Application of monochromatic imaging and polychromatic dynamic tomography

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

... dynamic tomography. Leslie G. Butler a , Corresponding Author Contact Information , E-mail Th... more ... dynamic tomography. Leslie G. Butler a , Corresponding Author Contact Information , E-mail The Corresponding Author , Burkhard Schillinger b , Kyungmin Ham c , Tabbetha A. Dobbins d , e , Ping Liu f and John J. Vajo f. a Department ...

Scientific Reports, 2021

Imaging using scintillators is a widespread and cost-effective approach in radiography. While dif... more Imaging using scintillators is a widespread and cost-effective approach in radiography. While different types of scintillator and sensor configurations exist, it can be stated that the detection efficiency and resolution of a scintillator-based system strongly depend on the scintillator material and its thickness. Recently developed event-driven detectors are capable of registering spots of light emitted by the scintillator after a particle interaction, allowing to reconstruct the Center-of-Mass of the interaction within the scintillator. This results in a more precise location of the event and therefore provides a pathway to overcome the scintillator thickness limitation and increase the effective spatial resolution of the system. Utilizing this principle, we present a detector capable of Time-of-Flight imaging with an adjustable field-of-view, ad-hoc binning and re-binning of data based on the requirements of the experiment including the possibility of particle discrimination via ...

A marker-free 3 D image registration for the ANCIENT CHARM project . Case study with neutron and X-ray tomography datasets

The aim of the ambitious ANCIENT CHARM project is the development of new imaging methods for a no... more The aim of the ambitious ANCIENT CHARM project is the development of new imaging methods for a non-destructive analysis of archaeological objects using neutron beams: Neutron Resonant Capture Imaging, Prompt Gamma Activation Imaging and Neutron Diffraction To-mography. Together with the well-established Neutron Tomography, these methods will provide a comprehensive and complementary set of position dependent information for the examined objects. The information they provide includes internal structure , strain, phase and elemental composition. One of the crucial tasks of the project is a detailed comparison of the 3-dimensional information provided by every single method. A precise alignment of the 3D data from each method is an essential prerequisite. A common approach is to use external markers fixed on the examined object and use them to align the data. In this article we explore the practicability of an alternative method that would precisely align the images without the use of ...

Physical Review B, 2018

With a full set of experimentally obtained self-and interdiffusion coefficients, we are able to v... more With a full set of experimentally obtained self-and interdiffusion coefficients, we are able to verify the relation between different transport coefficients in binary glass-forming Zr-Ni liquids. Despite a thermodynamic strong tendency of mixing, the interdiffusion is up to a factor of 2 slower than that predicted by the Darken equation. With the help of mode-coupling theory calculations, we identify that this is due to a slow, dominating kinetic contribution, arising from the dense packing of the melt, and the coupling of dynamics due to the strong Zr-Ni affinity. As a consequence, the cross correlation is on the order of 0.5 or less, whose contribution cannot be neglected, which seems to be a general feature of the glass-forming melts.

Investigations of the hydrogen diffusion and distribution in Zirconium by means of Neutron Imaging

Kerntechnik, 2018

Absorbed hydrogen degrades the mechanical properties of zirconium alloys used for nuclear fuel cl... more Absorbed hydrogen degrades the mechanical properties of zirconium alloys used for nuclear fuel claddings. Not only the total amount of hydrogen absorbed in the cladding tube but also the zirconium hydride orientation and its distribution influence the toughness of the material. For instance, the so-called delayed hydride cracking is caused by the diffusive re-distribution of hydrogen into the dilative elastic strain field ahead of crack tips. The paper presents in-situ and ex-situ neutron imaging investigations of hydrogen uptake, diffusion and distribution in zirconium alloys used for claddings. An overview about results of in-situ experiments studying the hydrogen uptake in strained Zircaloy-4, as well as ex-situ investigations of the diffusion of hydrogen in cold rolled Zircaloy-2 and Zr-2.5 % Nb alloy depending on temperature, rolling direction and thermal treatment and of the hydrogen re-distribution in the β-phase of Zircaloy-4 during a Three-Point-Bending-Test at 600 °C are p...

Water management in novel direct membrane deposition fuel cells under low humidification

International Journal of Hydrogen Energy, 2016

Abstract Polymer electrolyte membrane fuel cells (PEMFCs) fabricated by direct membrane depositio... more Abstract Polymer electrolyte membrane fuel cells (PEMFCs) fabricated by direct membrane deposition (DMD) were shown to work even at dry conditions without significant deterioration of the membrane resistance. Here, in situ neutron radiography is used to investigate the water management in those fuel cells to uncover the phenomena that lead to the robust operation under low humidification. A constant level of humidification within the membrane electrode assembly (MEA) of a DMD fuel cell is observed even under dry anode operation and 15% relative humidity on the cathode side. This proves a pronounced back diffusion of generated water from the cathode side to the anode side through the thin deposited membrane layer. Over the entire range of polarization curves a very high similarity of the water evolution in anode and cathode flow fields is found in spite of different humidification levels. It is shown that the power density of directly deposited membranes in contrast to a 50 μm thick N-112 membrane is only marginally affected by dry operation conditions. Water profiles in through-plane direction of the MEA reveal that the water content in the DMD fuel cell remains steady even at high current densities. This is in contrast to the N-112 reference fuel cell which shows a strong increase in membrane resistance and a reduced MEA water content with raising current densities. Thus this new MEA fabrication technique has a promising perspective, since dry operation conditions are highly requested in order to reduce fuel cell system costs.

Physics Procedia, 2015

The hydrogen concentration and distribution at both sides of the burst opening of cladding tubes ... more The hydrogen concentration and distribution at both sides of the burst opening of cladding tubes used in three QUENCH-LOCA simulation bundle experiments were investigated by means of neutron radiography and tomography. The quantitative correlation between the total macroscopic neutron cross-section and the atomic number density ratio between hydrogen and zirconium was determined by testing calibration specimens with known hydrogen concentrations. Hydrogen enrichments located at the end of the ballooning zone of the tested tubes were detected in the inner rods of the test bundles. Nearly all of the peripheral claddings exposed to lower temperatures do not show such enrichments. This implies that under the conditions investigated a threshold temperature exists below which no hydrogen enrichments can be formed. In order to understand the hydrogen distribution a model was developed describing the processes occurring during loss of coolant accidents after rod burst. The general shape of the hydrogen distributions with a peak each side of the ballooning region is well predicted by this model whereas the absolute concentrations are underestimated compared to the results of the neutron tomography investigations. The model was also used to discuss the influence of the alloy composition on the secondary hydrogenation. Whereas the relations for the maximal hydrogen concentrations agree well for one and the same alloy, the agreement for tests with different alloys is less satisfying, showing that material parameters such as oxidation kinetics, phase transition temperature for the zirconium oxide, and yield strength and ductility at high temperature have to be taken into account to reproduce the results of neutron imaging investigations correctly.

Physics Procedia, 2015

A common denominator of all neutron radiography (NRAD) facilities worldwide is that the perimeter... more A common denominator of all neutron radiography (NRAD) facilities worldwide is that the perimeter of the experimental chamber of the facility is a radiation shielding structure which, in some cases, also includes flight tube and filter chamber structures. These chambers are normally both located on the beam port floor outside the biological shielding of the neutron source. The main function of the NRAD-shielding structure is to maintain a radiological safe working environment in the entire beam hall according to standards set by individual national radiological safety regulations. In addition, the shielding's integrity and capability should not allow, during NRAD operations, an increase in radiation levels in the beam port hall and thus negatively affect adjacent scientific facilities (e.g. neutron diffraction facilities). As a bonus, the shielding for the NRAD facility should also prevent radiation scattering towards the detector plane and doing so, thus increase the capability of obtaining better quantitative results. This paper addresses Monte Carlo neutron-particle transport simulations to theoretically optimize the shielding capabilities of the biological barrier for the SANRAD facility at the SAFARI-1 nuclear research reactor in South Africa. The experimental process to develop the shielding, based on the principles of the ANTARES facility, is described. After casting, the homogeneity distribution of these concrete mix materials is found to be near perfect and first order experimental radiation shielding characteristics through film badge (TLD) exposure show acceptable values and trends in neutron-and gamma-ray attenuation.

5th International Topical Meeting on Neutron Radiography

Neutron Radiography - WCNR-11, 2020

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licens... more Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under license by Materials Research Forum LLC.

Zirconium in the Nuclear Industry: 18th International Symposium, 2018

Physics Procedia, 2017

In parallel to the upgrade of neutron imaging facility at TRR-1/M1 since 2015, the practice on im... more In parallel to the upgrade of neutron imaging facility at TRR-1/M1 since 2015, the practice on image processing software has led to implementation of neutron tomography (NT). The current setup provides a thermal neutron flux of 1.08×10 6 cm-2 sec-1 at the exposure position. In general, the sample was fixed on a plate at the top of rotary stage controlled by Labview 2009 Version 9.0.1. The incremental step can be adjusted from 0.45 to 7.2 degree. A 16 bit CCD camera assembled with a Nikkor 50 mm f/1.2 lens was used to record light from 6 LiF/ZnS (green) neutron converter screen. The exposure time for each shot was 60 seconds, resulting in the acquisition time of approximately three hours for completely turning the sample around. Afterwards, the batch of two dimensional neutron images of the sample was read into the reconstruction and visualization software Octopus reconstruction 8.8 and Octopus visualization 2.0, respectively. The results revealed that the system alignment is important. Maintaining the stability of heavy sample at every particular angle of rotation is important. Previous alignment showed instability of the supporting plane while tilting the sample. This study showed that the sample stage should be replaced. Even though the NT is a lengthy process and involves large data processing, it offers an opportunity to better understand features of an object in more details than with neutron radiography. The digital NT also allows us to separate inner features that appear superpositioned in radiography by cross-sectioning the 3D data set of an object without destruction. As a result, NT is a significant tool for revealing hidden information included in the inner structure of cultural heritage objects, providing great benefits in archaeological study, conservation process and authenticity investigating.

Physics Procedia, 2015

The University of California, Davis McClellan Nuclear Research Center (MNRC) operates a 2 MW TRIG... more The University of California, Davis McClellan Nuclear Research Center (MNRC) operates a 2 MW TRIGA TM reactor, which is currently the highest power TRIGA TM reactor in the United States. The Center was originally build by the US Air Force to detect hidden defects in aircraft structures using neutron radiography; the Center can accommodate samples as large as 10.00 m long, 3.65 m high, and weighing up to 2,270 kg. The MNRC reactor can be pulsed to 350 MW for about 30 ms (FWHM). The combination of a short neutron pulse with a fast microchannel plate based neutron detector enables high-resolution flash neutron radiography to complement conventional neutron radiography

The application of 3D computed tomography with X-rays and neutrons to visualize archaeological objects in blocks of soil

Studies in Conservation, 2010

Abstract The examination of archaeological objects lifted in blocks of soil is very time-consumin... more Abstract The examination of archaeological objects lifted in blocks of soil is very time-consuming; both this fact and the array of findings make it imperative to find new techniques of analysis and documentation to ensure archaeological interpretation. Computed tomography of such blocks of soil could be a non-destructive alternative to conventional methods. In the present study, the use of 3D computed tomography with X-rays (XCT) and neutrons (NCT) was reviewed and compared with conventional radiography and the manual unearthing and documentation of the objects. In almost every case it was possible to resolve all relevant archaeological questions by XCT. In some special cases it was not possible to visualize all organic materials. In contrast to XCT, NCT, which is very sensitive to hydrogen, visualizes organic materials much better than X-rays. On the other hand the high water content in the plaster and soil around the objects caused some problems because of this sensitivity to hydrogen. However, very good results were obtained with NCT when applied to already separated single metal objects with organic remains on their surface.

7th International Topical Meeting on Neutron Radiography (Itmnr-7), 2013

Imaging an intact, commercial battery as it cycles and wears is proved possible with neutron imag... more Imaging an intact, commercial battery as it cycles and wears is proved possible with neutron imaging. The wavelength range of imaging neutrons corresponds nicely with crystallographic dimensions of the electrochemically active species and the metal electrodes are relatively transparent. The time scale of charge/discharge cycling is well matched to dynamic tomography as performed with a golden ratio based projection angle ordering. The hydrogen content does create scatter which tends to blur internal structure. In this report, three neutron experiments will be described: 3D images of charged and discharged batteries were obtained with monochromatic neutrons at the FRM II reactor. 2D images (PSI) of fresh and worn batteries as a function of charge state may show a new wear pattern. In situ neutron diffraction (SNS) of the intact battery provides more information about the concentrations of electrochemical species within the battery as a function of charge state and wear. The combination of 2D imaging, 3D imaging, and diffraction data show how neutron imaging can contribute to battery development and wear monitoring.

Journal of Neutron Research, 2008

Even the most powerful steady-state neutron sources do not deliver sufficient flux for neutron im... more Even the most powerful steady-state neutron sources do not deliver sufficient flux for neutron imaging with microsecond time resolution. The future pulsed neutron spallation sources will offer a much higher peak flux, but have a low repetition rate that makes sequential data collection and synchronization for repetitive motions rather difficult. This paper proposes an asynchronous data collection scheme for recording movies of fast continuous repetitive motions like running combustion engines.

Neutronen sehen, was Röntgenstrahlen verborgen bleibt

D. B. Dingwell, Y. Lavallée, K.-U. Hess, A. Flaws, J. Marti, A. R. L. Nichols, H. A. Gilg, and B.... more D. B. Dingwell, Y. Lavallée, K.-U. Hess, A. Flaws, J. Marti, A. R. L. Nichols, H. A. Gilg, and B. Schillinger Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Theresienstr. 41/III, 80333 München, Germany Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, UK Consejo Superior de Investigations Cientificas, Institute of Earth Sciences Jaume Almera, Barcelona, Spain Research and Development Center for Ocean Drilling Science, Japan Agency for Marine Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan Ingenieursfakultät Bau Geo Umwelt, Technische Universität München, München, Germany Forschungsreaktor FRM-II, Technische Universität München, Garching, Germany

Neutron Tomography

Neutron Scattering in Novel Materials, 2000

Neutron imaging of a commercial Li-ion battery during discharge: Application of monochromatic imaging and polychromatic dynamic tomography

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

... dynamic tomography. Leslie G. Butler a , Corresponding Author Contact Information , E-mail Th... more ... dynamic tomography. Leslie G. Butler a , Corresponding Author Contact Information , E-mail The Corresponding Author , Burkhard Schillinger b , Kyungmin Ham c , Tabbetha A. Dobbins d , e , Ping Liu f and John J. Vajo f. a Department ...

Scientific Reports, 2021

Imaging using scintillators is a widespread and cost-effective approach in radiography. While dif... more Imaging using scintillators is a widespread and cost-effective approach in radiography. While different types of scintillator and sensor configurations exist, it can be stated that the detection efficiency and resolution of a scintillator-based system strongly depend on the scintillator material and its thickness. Recently developed event-driven detectors are capable of registering spots of light emitted by the scintillator after a particle interaction, allowing to reconstruct the Center-of-Mass of the interaction within the scintillator. This results in a more precise location of the event and therefore provides a pathway to overcome the scintillator thickness limitation and increase the effective spatial resolution of the system. Utilizing this principle, we present a detector capable of Time-of-Flight imaging with an adjustable field-of-view, ad-hoc binning and re-binning of data based on the requirements of the experiment including the possibility of particle discrimination via ...

A marker-free 3 D image registration for the ANCIENT CHARM project . Case study with neutron and X-ray tomography datasets

The aim of the ambitious ANCIENT CHARM project is the development of new imaging methods for a no... more The aim of the ambitious ANCIENT CHARM project is the development of new imaging methods for a non-destructive analysis of archaeological objects using neutron beams: Neutron Resonant Capture Imaging, Prompt Gamma Activation Imaging and Neutron Diffraction To-mography. Together with the well-established Neutron Tomography, these methods will provide a comprehensive and complementary set of position dependent information for the examined objects. The information they provide includes internal structure , strain, phase and elemental composition. One of the crucial tasks of the project is a detailed comparison of the 3-dimensional information provided by every single method. A precise alignment of the 3D data from each method is an essential prerequisite. A common approach is to use external markers fixed on the examined object and use them to align the data. In this article we explore the practicability of an alternative method that would precisely align the images without the use of ...

Physical Review B, 2018

With a full set of experimentally obtained self-and interdiffusion coefficients, we are able to v... more With a full set of experimentally obtained self-and interdiffusion coefficients, we are able to verify the relation between different transport coefficients in binary glass-forming Zr-Ni liquids. Despite a thermodynamic strong tendency of mixing, the interdiffusion is up to a factor of 2 slower than that predicted by the Darken equation. With the help of mode-coupling theory calculations, we identify that this is due to a slow, dominating kinetic contribution, arising from the dense packing of the melt, and the coupling of dynamics due to the strong Zr-Ni affinity. As a consequence, the cross correlation is on the order of 0.5 or less, whose contribution cannot be neglected, which seems to be a general feature of the glass-forming melts.

Investigations of the hydrogen diffusion and distribution in Zirconium by means of Neutron Imaging

Kerntechnik, 2018

Absorbed hydrogen degrades the mechanical properties of zirconium alloys used for nuclear fuel cl... more Absorbed hydrogen degrades the mechanical properties of zirconium alloys used for nuclear fuel claddings. Not only the total amount of hydrogen absorbed in the cladding tube but also the zirconium hydride orientation and its distribution influence the toughness of the material. For instance, the so-called delayed hydride cracking is caused by the diffusive re-distribution of hydrogen into the dilative elastic strain field ahead of crack tips. The paper presents in-situ and ex-situ neutron imaging investigations of hydrogen uptake, diffusion and distribution in zirconium alloys used for claddings. An overview about results of in-situ experiments studying the hydrogen uptake in strained Zircaloy-4, as well as ex-situ investigations of the diffusion of hydrogen in cold rolled Zircaloy-2 and Zr-2.5 % Nb alloy depending on temperature, rolling direction and thermal treatment and of the hydrogen re-distribution in the β-phase of Zircaloy-4 during a Three-Point-Bending-Test at 600 °C are p...

Water management in novel direct membrane deposition fuel cells under low humidification

International Journal of Hydrogen Energy, 2016

Abstract Polymer electrolyte membrane fuel cells (PEMFCs) fabricated by direct membrane depositio... more Abstract Polymer electrolyte membrane fuel cells (PEMFCs) fabricated by direct membrane deposition (DMD) were shown to work even at dry conditions without significant deterioration of the membrane resistance. Here, in situ neutron radiography is used to investigate the water management in those fuel cells to uncover the phenomena that lead to the robust operation under low humidification. A constant level of humidification within the membrane electrode assembly (MEA) of a DMD fuel cell is observed even under dry anode operation and 15% relative humidity on the cathode side. This proves a pronounced back diffusion of generated water from the cathode side to the anode side through the thin deposited membrane layer. Over the entire range of polarization curves a very high similarity of the water evolution in anode and cathode flow fields is found in spite of different humidification levels. It is shown that the power density of directly deposited membranes in contrast to a 50 μm thick N-112 membrane is only marginally affected by dry operation conditions. Water profiles in through-plane direction of the MEA reveal that the water content in the DMD fuel cell remains steady even at high current densities. This is in contrast to the N-112 reference fuel cell which shows a strong increase in membrane resistance and a reduced MEA water content with raising current densities. Thus this new MEA fabrication technique has a promising perspective, since dry operation conditions are highly requested in order to reduce fuel cell system costs.

Physics Procedia, 2015

The hydrogen concentration and distribution at both sides of the burst opening of cladding tubes ... more The hydrogen concentration and distribution at both sides of the burst opening of cladding tubes used in three QUENCH-LOCA simulation bundle experiments were investigated by means of neutron radiography and tomography. The quantitative correlation between the total macroscopic neutron cross-section and the atomic number density ratio between hydrogen and zirconium was determined by testing calibration specimens with known hydrogen concentrations. Hydrogen enrichments located at the end of the ballooning zone of the tested tubes were detected in the inner rods of the test bundles. Nearly all of the peripheral claddings exposed to lower temperatures do not show such enrichments. This implies that under the conditions investigated a threshold temperature exists below which no hydrogen enrichments can be formed. In order to understand the hydrogen distribution a model was developed describing the processes occurring during loss of coolant accidents after rod burst. The general shape of the hydrogen distributions with a peak each side of the ballooning region is well predicted by this model whereas the absolute concentrations are underestimated compared to the results of the neutron tomography investigations. The model was also used to discuss the influence of the alloy composition on the secondary hydrogenation. Whereas the relations for the maximal hydrogen concentrations agree well for one and the same alloy, the agreement for tests with different alloys is less satisfying, showing that material parameters such as oxidation kinetics, phase transition temperature for the zirconium oxide, and yield strength and ductility at high temperature have to be taken into account to reproduce the results of neutron imaging investigations correctly.

Physics Procedia, 2015

A common denominator of all neutron radiography (NRAD) facilities worldwide is that the perimeter... more A common denominator of all neutron radiography (NRAD) facilities worldwide is that the perimeter of the experimental chamber of the facility is a radiation shielding structure which, in some cases, also includes flight tube and filter chamber structures. These chambers are normally both located on the beam port floor outside the biological shielding of the neutron source. The main function of the NRAD-shielding structure is to maintain a radiological safe working environment in the entire beam hall according to standards set by individual national radiological safety regulations. In addition, the shielding's integrity and capability should not allow, during NRAD operations, an increase in radiation levels in the beam port hall and thus negatively affect adjacent scientific facilities (e.g. neutron diffraction facilities). As a bonus, the shielding for the NRAD facility should also prevent radiation scattering towards the detector plane and doing so, thus increase the capability of obtaining better quantitative results. This paper addresses Monte Carlo neutron-particle transport simulations to theoretically optimize the shielding capabilities of the biological barrier for the SANRAD facility at the SAFARI-1 nuclear research reactor in South Africa. The experimental process to develop the shielding, based on the principles of the ANTARES facility, is described. After casting, the homogeneity distribution of these concrete mix materials is found to be near perfect and first order experimental radiation shielding characteristics through film badge (TLD) exposure show acceptable values and trends in neutron-and gamma-ray attenuation.