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Referierte Publikation
- nein (1913) (entfernen)
Schlagworte
- Additive Manufacturing (49)
- Corrosion (49)
- Korrosion (45)
- LIBS (30)
- Additive manufacturing (27)
- Concrete (26)
- Fluorescence (26)
- Nanoparticles (24)
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Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (390)
- 7 Bauwerkssicherheit (308)
- 6 Materialchemie (274)
- 1 Analytische Chemie; Referenzmaterialien (236)
- 3 Gefahrgutumschließungen; Energiespeicher (188)
- 9 Komponentensicherheit (188)
- 4 Material und Umwelt (186)
- 5 Werkstofftechnik (139)
- 2 Prozess- und Anlagensicherheit (133)
- 7.6 Korrosion und Korrosionsschutz (114)
- 9.3 Schweißtechnische Fertigungsverfahren (107)
- 8.0 Abteilungsleitung und andere (105)
- 6.6 Physik und chemische Analytik der Polymere (91)
- 8.5 Röntgenbildgebung (82)
- 2.1 Sicherheit von Energieträgern (78)
- 8.4 Akustische und elektromagnetische Verfahren (75)
- 1.4 Prozessanalytik (66)
- 6.1 Oberflächen- und Dünnschichtanalyse (65)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (64)
- 6.3 Strukturanalytik (57)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (57)
- 7.2 Ingenieurbau (56)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (56)
- 9.4 Integrität von Schweißverbindungen (55)
- S Qualitätsinfrastruktur (52)
- 4.5 Kunst- und Kulturgutanalyse (49)
- 3.2 Gefahrguttanks und Unfallmechanik (45)
- 3.0 Abteilungsleitung und andere (43)
- 4.2 Material-Mikrobiom Wechselwirkungen (39)
- 5.1 Mikrostruktur Design und Degradation (38)
- 7.4 Baustofftechnologie (38)
- 1.2 Biophotonik (37)
- 1.1 Anorganische Spurenanalytik (36)
- 1.9 Chemische und optische Sensorik (36)
- 4.1 Biologische Materialschädigung und Referenzorganismen (36)
- 3.3 Sicherheit von Transportbehältern (35)
- 3.4 Sicherheit von Lagerbehältern (35)
- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (34)
- 6.2 Material- und Oberflächentechnologien (34)
- 1.8 Umweltanalytik (33)
- 8.6 Faseroptische Sensorik (33)
- 3.1 Sicherheit von Gefahrgutverpackungen und Batterien (32)
- 7.1 Baustoffe (31)
- 5.2 Metallische Hochtemperaturwerkstoffe (30)
- 6.7 Materialsynthese und Design (30)
- S.2 Digitalisierung der Qualitätsinfrastruktur (29)
- 5.4 Multimateriale Fertigungsprozesse (27)
- 1.6 Anorganische Referenzmaterialien (24)
- 5.3 Polymere Verbundwerkstoffe (21)
- 9.5 Tribologie und Verschleißschutz (21)
- 4.0 Abteilungsleitung und andere (20)
- 5.6 Glas (19)
- 4.3 Schadstofftransfer und Umwelttechnologien (18)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (18)
- S.3 Ökodesign und Energieverbrauchskennzeichnung (18)
- 1.7 Organische Spuren- und Lebensmittelanalytik (17)
- 7.7 Modellierung und Simulation (16)
- 2.2 Prozesssimulation (15)
- 2.4 Prüfung und Bewertung von Explosivstoffen/Pyrotechnik (15)
- 5.5 Materialmodellierung (14)
- 7.0 Abteilungsleitung und andere (13)
- 1.5 Proteinanalytik (12)
- 2.0 Abteilungsleitung und andere (12)
- 2.3 Einstufung von Gefahrstoffen und -gütern (11)
- 9.2 Versuchsanlagen und Prüftechnik (11)
- P Präsident (10)
- P.0 Präsident und andere (8)
- 2.5 Konformitätsbewertung Explosivstoffe/Pyrotechnik (7)
- 7.3 Brandingenieurwesen (7)
- 5.0 Abteilungsleitung und andere (6)
- 9.0 Abteilungsleitung und andere (6)
- 6.0 Abteilungsleitung und andere (3)
- 9.6 Additive Fertigung metallischer Komponenten (3)
- S.1 Qualität im Prüfwesen (3)
- 3.5 Sicherheit von Gasspeichern (2)
- S.0 Abteilungsleitung und andere (2)
- Z Zentrale Dienstleistungen (2)
- Z.1 Organisation, Controlling (2)
- 1.3 Instrumentelle Analytik (1)
- KM Kommunikation, Marketing (1)
- PST Präsidiale Stabsstelle (1)
Eingeladener Vortrag
- nein (1102)
High heat input leads to grain coarsening and softening in WM and HAZ; the tensile strength is reduced. Low heat input leads to inadmissible hardening in the WM; the impact strength is reduced.
The proposed t8/5-time of 3 s to 15 s could be achieved through the reduced welding velocity.
The concept of electromagnetic weld pool support system allowed single-pass welds in flat position without gravity drop-outs even for reduced welding speeds; in this way the heat input can be controlled.
The adaptation of the electromagnetic weld pool support system to laser and laser hybrid welding process can dramatically increase the potential field of application of these technologies for real industrial implementation.
Single-pass Hybrid Laser Arc Welding of Thick Materials Using Electromagnetic Weld Pool Support
(2019)
Hybrid laser-arc welding process allows single-pass welding of thick materials, provides good quality formation of joints with minimal thermal deformations and a high productivity in comparison with arc-based welding processes. Nevertheless, thick-walled steels with a thickness of 20 mm or more are still multi-pass welded using arc welding processes, due to increased process instability by increasing laser power. One limitation factor is the inadmissible formation of gravity drop-outs at the root. To prevent this, an innovative concept of electromagnetic weld pool support is used in this study. With help of such system a stable welding process can be established for 25 mm thick steel plates and beyond. Sound welds could be obtained which are tolerant to gaps and misalignment of the welded parts. The adaptation of this system to laser and hybrid laser-arc welding process can dramatically increase the potential field of application of these technologies for real industrial implementation.
The presented study deals with the performing and mechanical testing of single pass hybrid laser-arc welds (HLAW) on 25 mm thick plates made of steel grade S355J2. One of the challenges have to be solved at full penetration HLAW of thick plates is the drop formation occurring due to the disbalances of the forces acting in the keyhole and on the melt pool surface. Such irregularities mostly limit the use of high-power laser beam welding or HLAW of thick-walled constructions. To overcome this problem, an innovative concept of melt pool support based on generating Lorentz forces in the weld pool is used in this work. This method allows to perform high quality welds without sagging even for welding of 25 mm thick plates in flat position at a welding speed of 0.9 m min-1. For the obtain of full penetrated welds a laser beam power of 19 kW was needed. A high V-impact energy of up to 160 J could be achieved at the test temperature of 0 °C. Even at the most critical part in the weld root an impact energy of 60 J in average could be reached. The tensile strength of the weld reaches that of the base material. An introduce of the HLAW process with electromagnetic support of the melt pool in the industrial practice is an efficient alternative to the time- and cost-intensive arc-based multi-layer welding techniques which are established nowadays for joining of thick-walled constructions.
With global increases in clean energy demand, the natural gas is gaining in importance. Pipelines are the safest and most cost-effective way of transporting natural gas. Due to high transport volume and resulting high operation pressure, the demand for ultra-high strength steel grades such as X120 is very strong. As a result of the fact that these steels are produced by thermo-mechanical controlled processing, the welding process must be selected accordingly. Based on investigations, a high heat input such as by submerged arc welding process leads to softening in the weld metal and loss of strength whereas pure laser beam welding results in high cooling rates and deteriorate toughness of the weld metal. The objective of this research is to investigate the influence of heat input to mechanical properties of hybrid laser-arc welded pipeline steels of grade X120. Test specimens with a thickness of 20 mm could be welded without preheating in a single-pass with different welding velocities to observe the largest possible parameter window of the heat input. The achieved V-notch impact energy for hybrid laser-arc welded samples was 144±37 J at a testing temperature of -40 °C. With a tensile strength of 930±4 MPa the requirements of API 5L was achieved. To prevent gravity drop-outs at the slow welding speeds, an electromagnetic weld pool support system was used, which works contactless and is based on generating Lorentz forces. It was therefore possible to control the cooling rate in order to meet the requirements of the mechanical properties. By adapting the electromagnetic weld pool support to the laser and laser hybrid welding process, the application potential of these technologies for industrial implementation can be drastically increased.
The presentation summarizes our recent results on the coupled electrochemical methods for high resolution corrosion studies. The combination of Scanning Electrochemical Microscopy (SECM) and multielectrode (MMA) based real-time corrosion monitoring was presented as a new method for achieving high time resolution in local electrochemical analysis. Correlative imaging by means of Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) was demonstrated as a tool for the investigation of local corrosion processes initiated by the intermetallic particles (IMPs) on AA2024-T3 aluminium alloy.
The performance of functional coatings and adhesively joined hybrid components relies strongly on the stability of the polymer-metal interface. With the increasing utilization of multi-material structures in the automotive and aerospace industry, it is of great scientific and technical interest to understand the processes leading to interface degradation and to develop novel strategies to increase corrosion and delamination resistance.
The aim of this project is to develop thin epoxy-based films and their carbon nanofiller loaded composites on aluminium alloy AA2024-T3 as a model system and to investigate their interfacial stability under corrosive and coupled corrosive-mechanical load. Spin coating was used for the layer-by-layer deposition of poly[(o-cresyl glycidyl ether)-co-formaldehyde] and poly-(ethylenimine) bi-layers. Atomic force microscopy (AFM) results indicate a very homogeneous and dense film with low surface roughness. Carbon nanofillers were introduced either by mixing into the coating components or in between individual layers to control the separation between the carbon nanofillers and alloy surface. The film chemistry and barrier properties were characterized by means of spectroscopic and electrochemical methods, respectively. The degradation and delamination behavior of the epoxy-based films was characterized by means of in situ AFM corrosion experiments. The quantitative imaging (QI) mode allowed the observation of hydrogen-generation induced blister formation during exposure to corrosive electrolyte and how the local corrosion processes evolved with exposure time. Complementary energy dispersive X-ray spectroscopy (EDX) analysis was performed to correlate the corrosion behavior with the different intermetallic particle chemistries and distributions. The presentation will summarize our results on the effect of interface chemistry and carbon nanofiller – alloy separation on the initiation of local corrosion processes on thin film covered AA2024-T3 aluminium alloys.
In service, most materials are operated under simultaneous corrosive and mechanical load and there are very few methods capable for testing material degradation under these conditions, especially when it comes to high resolution analysis. For this purpose, in this work, a tensile module capable of uniaxial stretching and compression with up to 5 kN force was integrated into an AFM stage. The elimination of the need for sample unmounting and remounting and the resulting possibility of keeping the sample under constant mechanical load during AFM measurements not only enables a precise positioning of the area of interest but also allows for the analysis of processes in the elastic deformation regime.
This methodology was demonstrated for two case studies. Scanning Kelvin Probe Force Microscopy (SKPFM) was used as the main tool to characterize the deformation behavior. Moreover, a flexible electrochemical measurement cell was used to enable electrochemical analysis by means of electrochemical impedance spectroscopy (EIS) and Linear Sweep Voltammetry (LSV) during AFM measurements at different levels of strain. The in situ AFM results are complemented by microstructure analysis by means of electron backscatter diffraction (EBSD).
In the first case study, the deformation induced delamination of a thin organic coating on AA2024 T3 aluminium alloy was investigated as a function of alloy surface treatment. The formation of cracks in the insulating passive film enabled an early detection of deformation processes by means of SKPFM. The second case study focused on the comparison of corrosion and deformation behavior of conventional and additively manufactured 316 stainless steels. In comparison to the conventional 316 stainless steel, the effect of processing was clearly detectable on the additively manufactured material as zones of inhomogeneous potential, which also affected the initiation of local corrosion processes. The contribution will provide detailed information on the new AFM setup and summarize our results from both case studies.
Dose enhancement by gold nanoparticles (AuNP) was shown to increase the biological effectiveness of radiation damage in biomolecules and tissue. Most of the current studies focus on external beam therapy on combination with AuNP. Here we present a Monte-Carlo study (Geant4) to characterise radioactive AuNP. Radioactive 198 Au emits beta and gamma rays and is considered for applications with solid tumours. To effectively apply 198 AuNP their energy deposit characteristics have to be determined in terms of intrinsic and extrinsic properties e.g. AuNP diameter, AuNP density, and their clustering behaviour. After each decay process, the energy deposit, inelastic scattering events, kinetic energy spectrum of secondary particles within the AuNP themselves and in a spherical target volume of water up to 1 μm radius were determined. Simulations were performed for AuNP radii ranging from 2.5 nm to 20 nm radius, different cluster sizes and densities. The results show an increase of the energy deposit in the vicinity of the AuNP up to 150 nm. This effect nearly vanishes for distances up to one micron. For the case of AuNP clusters and the same activity, the enhancement of the energy deposit increases with the relative gold mass percentage and therefore can be adjusted by changing AuNP radius or clustering behaviour.
Der Ersatz von Röntgenfilmen durch digitale Detektoren in der Zerstörungsfreien Prüfung im Anlagenbau wird seit 2013 durch neue ISO-Normen unterstützt. Nach der Erfolgsgeschichte der digitalen Photographie und der fast vollständigen Ablösung der Filmtechnik in der optischen Bilderfassung wird erwartet, dass sich der Übergang von der Filmradiographie zur digitalen Radiographie schnell vollzieht. Dieser Trend ist derzeit so noch nicht zu beobachten. Zur mobilen Prüfung wird in Europa immer noch vorrangig die Filmradiographie und nur teilweise die Computerradiographie mit Speicherfolien eingesetzt. Im Bereich der stationären Prüftechnik haben sich die Matrixdetektoren (DDA) weitgehend durchgesetzt, wobei es auch hier noch alternative Detektoren wie Bildverstärker und Fluoroskope gibt. Mit Einführung der DIN EN ISO 17636-2 zur Schweißnahtprüfung wird seit 2013 erstmalig geregelt, wie man einen digitalen Detektor für die technische Radiographie auswählen soll, um im Vergleich zur Filmradiographie eine äquivalente Bildqualität zu erhalten. Essentielle Parameter bestimmen, ob die geforderte Bildgüte (Fehlernachweißempfindlichkeit) erreicht wird. Ein Überblick zeigt, welche Parameter für den praktischen Einsatz wichtig sind und wie sie ermittelt werden. Praktische Einsatzbeispiele im Anlagenbau werden diskutiert.
In den letzten zwei Jahren wurden 11 neue Standards/Standardrevisionen zur RT veröffentlicht (ohne Strahlenschutz) und 5 werden dafür gestrichen. Es wird über die neuen Anforderungen ausgewählter Normen bzw. Normrevisionen informiert und insbesondere auch über die veränderten Parameter, die bei Prüfpraxis und bei der Klassifizierung zu berücksichtigen sind. Das wichtigste Projekt ist die Revision der DIN EN ISO 17636-1, -2, RT von Schweißverbindungen, in ISO TC 44 SC 5 WG 1. Die Standards zur Schweißnahtprüfung in der Kerntechnik, DIN 25435, wurden ins Englische übertragen und bei ISO TC 85 SC 6 bearbeitet. Hauptaktivität bei ASTM ist gegenwärtig die Überarbeitung der CT-Standards und die Berücksichtigung der Anforderungen an das dimensionelle Messen. Der Guide ASTM E 1441 zur Bestimmung von MTF, Kontrast-Detail-Funktion (CDF) und Kontrast-Diskrimination-Diagramm (CDD) wird revidiert. E 2445 zur CR Long Term Stability wird ebenfalls revidiert. Die Revision soll auch in die ISO 16371-1 eingehen. Dazu ist ein Round Robin-Test geplant. Auch die Standards zur Durchstrahlungsprüfung auf Korrosion und Ablagerungen in Rohren mit Röntgen- und Gammastrahlen (EN 16407-1, -2, 2014) wurden revidiert. Diese Revision wurde als DIN EN ISO 20769-1, -2 2018 veröffentlicht und EN 16407 wird zurückgezogen. Die Revision der Standards EN 12543 und EN 12679 zur Messung der Brennfleckgröße und der Strahlergröße ist mit Verzögerung in Überarbeitung, um die digitalen Detektoren und Messmöglichkeiten mit Bildverarbeitungsprogrammen zu berücksichtigen. Ein Entwurf zur Messung der Brennfleckgröße von nano-Fokusröhren wird derzeit vom Europäischen Metrologie-Programm EMPIR gefördert. Zur radiographischen Gussteilprüfung wurde der Standard EN 12681 revidiert und 2018 veröffentlicht. Er wurde um Zulässigkeitsgrenzen erweitert und die digitale Radiographie wurde in Teil 2 berücksichtigt.
Metallische Mikropartikel in der Größenfraktion von ca. 10 – 100 Mikrometer bilden das Grundmaterial für den additiven Aufbau komplexer Strukturen durch lokales Aufschmelzen mit einem Laserstrahl. Entscheidend für dieses Verfahren ist die Kenntnis der Größen-, Form- und Defektverteilungen von Partikelfraktionen, da sie direkten Einfluss auf die Fließfähigkeit des Pulvers während des lagenweisen Auftragens, als auch auf die finale innere Porosität des Bauteils haben. Im Pulver vorhandene Poren verlassen in der Regel das Schmelzbad vor dem Erstarren nicht wieder, da deren Konvektionszeiten größer sind als die Zeit, während der das lokale Schmelzbad besteht, so dass einmal durch die Ausgangspartikel eingebrachte Poren in der Regel auch im fertigen Bauteil verbleiben. Eine strenge Qualitätskontrolle des Ausgangspulvers ist also Voraussetzung, um hochwertige Bauteile mit geringer Restporosität zu erhalten. Der Vorteil der Röntgentomographie ist dabei, dass mit nur sehr geringem Präparationsaufwand innenliegende Poren bis zu einem Durchmesser von wenigen Mikrometern detektiert werden können. Dies ist mit konkurrierenden Verfahren (Licht- / Elektronenmikroskopie, Laserbeugung) so nicht möglich. Zusammenfassend werden wir zeigen, dass die zerstörungsfreie Bildgebung mit der Röntgen-Mikrotomographie für die Qualitätskontrolle in der additiven Fertigung ein leistungsfähiges Werkzeug ist. Wir erörtern die Grenzen der Methode durch eine numerische Studie mithilfe des Simulationsprogramms aRTist. Dabei werden verschiedene Partikelgrößen dahingehend untersucht, welche Poren mit mikroradiographischen Verfahren detektierbar sind. Dazu wird ein Modell für eine dreilagige dichteste Kugelpackung entwickelt, so dass auch Überlagerungen von Anzeigen untersucht werden können. Im Ergebnis werden verschiedene Partikel- und Porengrößenkombinationen untersucht und die entsprechenden Detektionsgrenzen bestimmt.
Neben der klassischen Durchstrahlung wird die bildgebende Röntgen-rückstreuung bisher nur sehr begrenzt eingesetzt. Vor über 20 Jahren hatte Philips mit „COMSCAN“ eine erste industrielle Anwendung in der Luftfahrt gefunden, die sogar eine Tiefenauflösung besaß. Die Firma AS&E in Boston bietet Röntgenrückstreu-Anlagen für den Sicherheitsbereich an. In diesen wird mit einem hochkollimierten Nadelstrahl aus einem rotierenden Blendenrad ein Objekt einseitig abgetastet. Zur Detektion der gestreuten Strahlung aus dem Objekt werden großflächige Detektoren direkt neben dem rotierenden Nadelstrahlkollimator eingesetzt. Ein solcher Prototyp wird an der BAM für den Einsatz in der zerstörungsfreien Prüfung untersucht und optimiert. Als neues industrielles Einsatzgebiet wird dabei die in situ Überwachung in der additiven Fertigung avisiert. Hier ist die Zugänglichkeit zum entstehenden Werkstück in den 3D-Druckanlagen stark eingeschränkt, was den Einsatz einer zweiseitigen Durchstrahlung oder der Computer-Tomographie, bei der das Objekt rotiert wird, verhindert. Auch sind die in der additiven Fertigung eingesetzten Werkstoffe (Polymere, Keramik, Leichtmetalle wie Al oder Ti) für die Rückstreuung besser geeignet als Metalle höherer Dichte, da das Streusignal mit der Ordnungszahl und der Materialdichte abnimmt. Allerdings sind die Anforderungen an räumliche Auflösung und Kontrastempfindlichkeit in der zerstörungsfreien Prüfung additiv gefertigter Bauteil deutlich höher als im Sicherheitsbereich, da hier Bauteilfehler mit typischen Dimensionen kleiner als 1 mm sicher detektiert werden müssen. Die Untersuchung dieser Grenzen des derzeitigen Standes der Röntgenrückstreutechnik mit Nadelstrahl ist ein Teilbereich des mehrjährigen BAM-Themenfeldprojektes „ProMoAM“. Im Vortrag werden die ersten Ergebnisse der Optimierung sowie die gefundenen Anwendungsgrenzen an Beispielen erläutert.
Neues aus der BAM 2019
(2019)
X-ray back scatter imaging is rarely applied compared to classical X-ray projection imaging. More than 20 years ago the company Philips developed “COMSCAN”, a first application case for aircraft industry, which allowed even a depth resolution using back scatter imaging. The company AS&E in Boston offers back scatter imaging solutions for the security market. The principle is to scan the object with a highly collimated X-ray needle beam from one side only and to detect the backscattered radiation by a large area detector side by side with the collimation wheel. A new prototype is investigated at BAM for application and optimization in non-destructive testing. As modern industrial application field in-situ inspection in additive manufacturing is targeted. The accessibility of the printed part during the production process is very limited. This prevent the application of a two sided X-ray inspection or Computed Tomography, were an rotation of the object is required to acquire projections from 360 degrees. An important advantage for the X-ray back scatter technique are also the materials used in additive manufacturing (polymers, ceramics, light metals like Aluminum or Titanium). These materials with lower density and lower Z values give better scatter signals than metals with higher densities and Z values. The back scatter intensity decreases with increasing density and Z value of the material. But the requirements on spatial resolution and contrast sensitivity are more stringent for non-destructive testing of additive manufactured parts compared to the security area. In NDT sizes of indications smaller than 1 mm have to be detected clearly. The investigation of these limits on a state-of-the-art prototype for X-ray back scattering using rotating collimated X-ray needle beams is a part of the BAM project “ProMoAM”. The contribution shows first results of the optimization for NDT and the achieved application limits for several example cases.
Der Ersatz von Röntgenfilmen durch digitale Detektoren in der Zerstörungsfreien Prüfung im Anlagenbau wird seit 2013 durch neue ISO-Normen unterstützt. Nach der Erfolgsgeschichte der digitalen Photographie und der fast voll-ständigen Ablösung der Filmtechnik in der optischen Bilderfassung wird erwartet, dass sich der Übergang von der Filmradiographie zur digitalen Radiographie schnell vollzieht. Dieser Trend ist derzeit so noch nicht zu beobachten. Zur mobilen Prüfung wird in Europa immer noch vorrangig die Filmradiographie und nur teilweise die Computerra-diographie mit Speicherfolien eingesetzt. Im Bereich der stationären Prüftechnik haben sich die Matrixdetektoren (DDA) weitgehend durchgesetzt, wobei es auch hier noch alternative Detektoren wie Bildverstärker und Fluorosko-pe gibt. Mit Einführung der DIN EN ISO 17636-2 zur Schweißnahtprüfung wird seit 2013 erstmalig geregelt, wie man einen digitalen Detektor für die technische Radiographie auswählen soll, um im Vergleich zur Filmradiographie eine äquivalente Bildqualität zu erhalten. Essentielle Parameter bestimmen, ob die geforderte Bildgüte (Fehlernachweiß-empfindlichkeit) erreicht wird. Ein Überblick zeigt, welche Parameter für den praktischen Einsatz wichtig sind und wie sie ermittelt werden. Praktische Einsatzbeispiele im Anlagenbau werden diskutiert.
Die Technologie der hybriden Teilchen (oder Photonen) zählenden Bilddetektoren wurde seit mehr als 2 Jahrzehnten durch Institutionen wie das CERN (MediPix-/ TimePix-Chips) oder das Paul-Scherrer-Institut (Pilatus-/ Eiger-Chips) entwickelt. Die Ursprünge dieser Technologie kommen aus der Hochenergie-Physik mit ihren Beschleuniger-basierten Experimenten, bei denen ein zuverlässiger und rauschfreier Nachweis jedes ionisierten Teilchens gefordert wird. Eine Energieauflösung wird ebenfalls oft verlangr. Das ist auch in der klassischen Radiographie von Nutzen, so wurden diese Detektoren auch dafür optimiert. Neueste Photonen zählenden Detektoren besitzen folgende exzellenten Bildeigenschaften: rauschfreie Photonen-Detektion in einem hohen Dynamikbereich (SNR >2500 erreichbar), hohe räumliche Auflösung (bis zu 10 µm Pixelgröße), Energieschwellen bis zur vollen spektralen Auflösung und eine sehr hohe Geschwindigkeit (bis zu Tausenden Bildern pro Sekunde). Diese hybriden Detektoren können mit hochabsorbierenden Sensorschichten aus CdTe, CZT oder GaAs bestückt werden, um bildgebende Anwendungen mit Gamma- oder harten Röntgenstrahlen zu realisieren, in denen bisher Szintillator basierende Bilddetektoren dominierten (z.B. für NDT, SPECT, PET). Im Beitrag wird der erste wirklich große Photonen zählende Detektor mit CdTe und einer lückenlosen Detektionsfläche, die aus einer theoretisch unbegrenzten Anzahl von MediPix-/ TimePix-Modulen besteht, gezeigt. Die erste kommerzielle Version eines solchen Detektors hat eine Fläche von 7cm x7cm, 1,6 Megapixel und erfüllt die Anforderungen der Prüfklasse „B“ in der industriellen Radiographie. Die Energie auflösenden Fähigkeiten dieses Detektors erlauben eine „Farb-Radiographie“, in der verschiedene Materialien in verschiedene Farben dargestellt werden. Der 2. Teil dieses Beitrags stellt einen voll spektral auflösenden Gamma- und Röntgen-Bilddetektor mit dickem CdTe und 2,4 Megapixel vor, der auf TimePix3-Chips basiert und eine sehr hohe Ortsauflösung von ~10 µm erreicht. Die hohe Zeitauflösung von TimePix3 wird mit großem Nutzen für eine substantielle Verbesserung der erhaltenen Bilder und Spektren zur Unterdrückung interner Fluoreszenzstrahlung sowie Comptonstreuungsanteilen, die die Bildinformation verschmieren, verwendet.
In den letzten zwei Jahren wurden 11 neue Standards/Standardrevisionen zur RT veröffentlicht (ohne Strahlenschutz) und 5 werden dafür gestrichen. Es wird über die neuen Anforderungen ausgewählter Normen bzw. Normrevisionen informiert und insbesondere auch über die veränderten Parameter, die bei Prüfpraxis und bei der Klassifizierung zu berücksichtigen sind. Das wichtigste Projekt ist die Revision der DIN EN ISO 17636-1, -2, RT von Schweißverbindungen, in ISO TC 44 SC 5 WG 1. Die Standards zur Schweißnahtprüfung in der Kerntechnik, DIN 25435, wurden ins Englische übertragen und bei ISO TC 85 SC 6 bearbeitet. Hauptaktivität bei ASTM ist gegenwärtig die Überarbeitung der CT-Standards und die Berücksichtigung der Anforderungen an das dimensionelle Messen. Der Guide ASTM E 1441 zur Bestimmung von MTF, Kontrast-Detail-Funktion (CDF) und Kontrast-Diskrimination-Diagramm (CDD) wird revidiert. E 2445 zur CR Long Term Stability wird ebenfalls revidiert. Die Revision soll auch in die ISO 16371-1 eingehen. Dazu ist ein Round Robin-Test geplant. Auch die Standards zur Durchstrahlungsprüfung auf Korrosion und Ablagerungen in Rohren mit Röntgen- und Gammastrahlen (EN 16407-1, -2, 2014) wurden revidiert. Diese Revision wurde als DIN EN ISO 20769-1, -2 2018 veröffentlicht und EN 16407 wird zurückgezogen. Die Revision der Standards EN 12543 und EN 12679 zur Messung der Brennfleckgröße und der Strahlergröße ist mit Verzögerung in Überarbeitung, um die digitalen Detektoren und Messmöglichkeiten mit Bildverarbeitungsprogrammen zu berücksichtigen. Ein Entwurf zur Messung der Brennfleckgröße von nano-Fokusröhren wird derzeit vom Europäischen Metrologie-Programm EMPIR gefördert. Zur radiographischen Gussteilprüfung wurde der Standard EN 12681 revidiert und 2018 veröffentlicht. Er wurde um Zulässigkeitsgrenzen erweitert und die digitale Radiographie wurde in Teil 2 berücksichtigt.
X-ray back scatter imaging is rarely applied compared to classical X-ray projection imaging. 20 years ago the company Philips developed “COMSCAN”, a first application case in the aircraft industry, which allowed even a depth resolution using back scatter imaging. The company AS&E in Boston offers back scatter imaging solutions for the security market. Their principle is to scan the object with a highly collimated X-ray needle beam from one side only and detect the backscattered radiation by a large area detector side by side with the collimation wheel. A new prototype is investigated at BAM for application and optimization in non-destructive testing. As modern industrial application field in-situ testing in additive manufacturing is targeted. The accessibility of the printed part during the production process is very limited. This prevent the application of a two sided X-ray inspection or Computed Tomography, were an rotation of the object is required to acquire projections from 360 degrees. An important advantage for the X-ray back scatter technique are also the materials used in additive manufacturing (polymers, ceramics, light metals like Aluminum or Titanium). These materials with lower density and lower Z values give better scatter signals than metals with higher densities and Z values. The back scatter intensity decreases with increasing density and Z value of the material. But the requirements on spatial resolution and contrast sensitivity are more stringent for non-destructive testing of additive manufactured parts compared to the security area. In NDT sizes of indications smaller than 1 mm have to be detected clearly. The investigation of these limits on a stateof-the-art prototype for X-ray back scattering using rotating collimated X-ray needle beams is a part of the BAM project “ProMoAM”. The contribution shows first results of the optimization for NDT and the achieved application limits for several example cases.
X-ray back scatter imaging is rarely applied compared to classical X-ray projection imaging. 20 years ago the company Philips developed “COMSCAN”, a first application case in the aircraft industry, which allowed even a depth resolution using back scatter imaging. The company AS&E in Boston offers back scatter imaging solutions for the security market. Their principle is to scan the object with a highly collimated X-ray needle beam from one side only and detect the backscattered radiation by a large area detector side by side with the collimation wheel. A new prototype is investigated at BAM for application and optimization in non-destructive testing. As modern industrial application field in-situ testing in additive manufacturing is targeted. The accessibility of the printed part during the production process is very limited. This prevent the application of a two sided X-ray inspection or Computed Tomography, were an rotation of the object is required to acquire projections from 360 degrees. An important advantage for the X-ray back scatter technique are also the materials used in additive manufacturing (polymers, ceramics, light metals like Aluminum or Titanium). These materials with lower density and lower Z values give better scatter signals than metals with higher densities and Z values. The back scatter intensity decreases with increasing density and Z value of the material. But the requirements on spatial resolution and contrast sensitivity are more stringent for non-destructive testing of additive manufactured parts compared to the security area. In NDT sizes of indications smaller than 1 mm have to be detected clearly. The investigation of these limits on a stateof-the-art prototype for X-ray back scattering using rotating collimated X-ray needle beams is a part of the BAM project “ProMoAM”. The contribution shows first results of the optimization for NDT and the achieved application limits for several example cases.
The revision of ISO 24497:2007 started in 2017 (by decision of Com-V at the IIW annual assembly in Shanghai). After 3 years of discussions and incorporation of many comments from all over the world the working group C-V-E-b headed by Uwe Zscherpel finalized the work with a final draft to be forwarded for final vote at ISO TC 44. The working group C-V-E-b finalised the work and can be resolved. The chair thanks for all the successfully work done, the vote to forward the latest draft to ISO for final vote was done without any negative.
Das Kupferstichkabinett der Hamburger Kunsthalle besitzt seit seiner Gründung vier Zeichnungen von Leonardo da Vinci (1452–1519). Sie sind Teil eines umfangreichen Legats des Hamburger Kunsthändlers Georg Ernst Harzen, das der Stadt Hamburg für die 1869 eröffnete Kunsthalle als Besitz übereignet wurde. Die Zeichnungen gelten aufgrund ihrer Provenienzen und stilistischen Verankerung im Werk Leonardos als gesichert. Weiterführende materialtechnologische Untersuchungen wurden nun erstmals anlässlich der Ausstellung »Leonardo da Vinci – Die Zeichnungen im Hamburger Kupferstichkabinett« durchgeführt.
The layerwise slurry deposition (LSD) has been established in the recent years as a method for the deposition of ceramic powder layers. The LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade; each layer is sequentially deposited and dried to achieve a highly packed powder layer.
The combination of binder jetting and LSD was introduced as a novel technology named LSD-print. The LSD-print takes advantage of the speed of binder jetting to print large areas, parallel to the flexibility of the LSD, which allows the deposition of highly packed powder layers with a variety of ceramic materials.
The working principle and history of the LSD technology will be shortly discussed. A theoretical background will be also discussed, highlighting advantages and drawbacks of the LSD compared to the deposition of a dry powder.
The last part of the talk will be dedicated to highlight recent results on the LSD-print of SiSiC of geometrically complex components, in collaboration between BAM and HC Starck Ceramics GmbH. Density, microstructure and mechanical properties of LSD-printed and isostatic pressed samples will be discussed and compared.
Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability.
However, the flowability of the powder used in these processes is essential to achieve defect-free and densely packed powder layers. For standard powder bed AM technologies, this limits the use of many raw materials which are too fine or too cohesive.
This presentation will discuss the possibilities to either optimize the powder raw material to adapt it to the specific AM process, or to develop novel AM technologies which are able to process powders in a wider range of conditions.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of very fine ceramic particles.
In powder bed Additive Manufacturing (AM) technologies, a part is produced by depositing and piling up thin powder layers. In each layer, the cross section of the object to build is defined by locally consolidating the powder, by sintering/melting the material (powder bed fusion technologies) or by ink jetting a binder (binder jetting technologies).
These are already leading AM technologies for metals and polymers, thanks to their high productivity and scalability. The application of these techniques to most ceramics has been challenging so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of SLS/SLM and 3DP technologies for advanced ceramic materials. LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade. Each layer is deposited and dried to achieve a highly packed powder layer. The LSD offers high flexibility in the ceramic feedstock used, especially concerning material and particle size, and enables the production of parts with physical and mechanical properties comparable to pressed or slip-casted parts. In this presentation, the LSD technique will be introduced and several examples of application to porcelain, SiC and alumina products will be reported.
Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability.
However, the flowability of the powder used in these processes is essential to achieve defect-free and densely packed powder layers. For standard powder bed AM technologies, this limits the use of many raw materials which are too fine or too cohesive.
This presentation will discuss the possibilities to either optimize the powder raw material to adapt it to the specific AM process, or to develop novel AM technologies which are able to process powders in a wider range of conditions.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of very fine ceramic particles. Another technology, the Gas Flow Assisted Powder Deposition, can increase the stability of the powder bed and the packing density, even in extreme conditions such as in absence of gravitational forces.
Powder bed -based technologies are amongst the most successful Additive Manufacturing (AM) techniques. "Selective laser sintering/melting" (SLS/SLM) and "binder jetting 3D printing" (3DP) especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability. In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of SLS/SLM and 3DP technologies for advanced ceramic materials. LSD consists in the layer-by-layer deposition of a ceramic slurry by means of a doctor blade. Each layer is deposited and dried to achieve a highly packed powder layer, which can be used for SLM or for 3DP. This technique offers high flexibility in the ceramic feedstock used, especially concerning material and particle size, and is capable of producing parts with physical and mechanical properties comparable to traditionally shaped parts. In this presentation, the LSD technique will be introduced and several examples of application to porcelain, SiC and alumina products will be reported.
Das Projekt befasst sich mit einem neuen Ansatz, den pH-Wert im Beton zu bestimmen.
Der pH-Wert ist vor allem für Stahlbeton-Bauwerke von Bedeutung, da dieser maßgeblich die Korrosion des Stahls beeinflusst. Im frischen Beton liegt der pH-Wert im basischen Bereich.
Der Stahl ist in diesem Bereich passiviert, also vor schädlicher Korrosion geschützt. Durch die sogenannte Karbonatisierung sinkt der pH-Wert und die Korrosionswahrscheinlichkeit steigt deutlich an. Die Stabilität von Bauwerken in denen Stahlbeton verbaut ist, wird durch diese Korrosion langfristig beeinträchtigt. Allein in deutscher Infrastruktur rechnet man mit circa 5 Milliarden Euro Schaden jährlich.
Die entwickelte Methode verwendet Sonden, welche die Korrosion Monitoren sollen. Im Sondeninneren befindet sich eine Schicht pH-Indikator (Thymolblau) und eine Schicht mit Quantenpunkten. Die Quantenpunkte fluoreszieren, nach Anregung durch zum Beispiel einen Laser, bei circa 440 nm (blau) beziehungsweise 610 nm (gelb-orange). Das Thymolblau ist im basischen Milieu (pH > 9,6) blau, im neutralen Milieu (um pH 7) gelb-orange. Der Indikator wirkt wie ein Farbfilter und lässt, je nach pH-Wert, unterschiedliche Wellenlängen zur Glasfaser durch. Aus der gemessenen Intensität bei 440 nm und 610 nm kann ein Verhältnis ermittelt werden. Dieses Verhältnis lässt erkennen, welchen pH-Wert das Milieu besitzt, in dem sich die Sonde befindet.
Die entwickelte Methodik ist zerstörungsfrei, das heißt kein Material muss aus den Bauwerken entnommen werden. Vielmehr sollen die Sonden beim Betonieren in das Bauwerk eingebettet werden. Über Glasfasern können die Sonden jederzeit angesprochen werden. Dies ermöglicht permanentes pH-Monitoring, was die Früherkennung von Korrosionsgefahr verbessert und die Sanierungskosten verringert.
Alkali-silica reaction (ASR) is a serious Problem concerning the deterioration of concrete. This leads to significant maintenance and reconstruction costs for concrete infrastructures all over the world. The geographical regions, which play a major role in concrete deterioration, are for example coastal Areas or in general, areas with a high air humidity/salinity due to closeness of rivers or lakes.
These exemplary results show, the application of Raman spectroscopy establishes a valuable approach for characterizing the chemical and structural composition of ASR-products. The results prove the potential to trace the kind of reaction products, developing in dependence on the aggregate and to follow up its local alteration from origin of the gel.
Due to their high irradiance and wide modulation bandwidth, high-power lasers open up a wide field of application. For example, the classical methods of pulse and lock-in thermography can be realized in high quality. In addition, structured heating is also possible by using arrays of such lasers. This makes it possible to implement new thermographic methods, such as interference-based detection of cracks or super resolution.
Die thermografische ZfP basiert auf der Wechselwirkung von thermischen Wellen mit Inhomogenitäten. Diese Inhomogenitäten hängen mit der Probengeometrie oder der Materialzusammensetzung zusammen. Obwohl die Thermografie für ein breites Spektrum von Inhomogenitäten und Materialien geeignet ist, ist die grundlegende Einschränkung die diffuse Natur der thermischen Wellen und die Notwendigkeit, ihre Wirkung lediglich an der Probenoberfläche radiometrisch messen zu können. Die Ausbreitung der thermischen Wellen von der Wärmequelle über die Inhomogenität zur Detektionsoberfläche führt zu einer Verschlechterung des räumlichen Auflösungsvermögens der thermografischen Technik. Ein neuer konzertierter Ansatz auf Basis einer räumlich strukturierten Erwärmung und einer Joint Sparsity des Signalensembles ermöglicht eine verbesserte Rekonstruktion von Inhomogenitäten.
Im Beitrag wird die Implementierung dieses Ansatzes auf Basis einer strukturierten Beleuchtung mit einem 1D-Laser-Array vorgestellt. Die einzelnen Emitterzellen des Laser-Arrays werden durch ein pseudozufälliges Binärmuster gesteuert und zusätzlich leicht verschoben. Die wiederholte Messung dieser verschiedenen Konfigurationen bei gleichzeitig konstanter Inhomogenität ermöglicht eine Rekonstruktion der Inhomogenität unter Ausnutzung der Joint Sparsity.
The acronym IBESS stands for "Integrale Bruchmechanische Ermittlung der Schwingfestigkeit von Schweißverbindungen" which, translated from German, means "integral fracture mechanics determination of the fatigue strength of welds". the method introduced in this study is the outcome of a German Research cluster in which eight partners were involved. A list of them is found at the end this study. The IBESS method is characterized by a number of partially novel aspects and elements of fracture mechanics applied to the evaluation of fatigue stength of welds. The most important ones are: (a) Determination of fatigue crack propagation for mechanically/physically short and long cracks. (b) Determination of an elastic-plastic crack driving force for the treatment of mechanically short cracks. To that purpose an analytical expression for the cyclic J-integral was developed and validated against finite element results. (c) The gradual build-up of the crack closure phenomenon is determined by using cyclic R-curves which describe the crack size dependency of the fatigue crack propagation threshold in the physically short crack growth regime. (d) A physically meaningful initial crack size is defined for total life consideration. It is based on a two-criteria approach. Based on a cyclic R-curve analysis, the crack size at crack arrest is determined as a lower bound. If, however, a pre-existing crack-like defect is larger than this, its dimensions define the initial crack size. (e) Multiple crack propagation at the weld toe is considered. (f) In conjunction with this, the variation of the weld toe geometry is considered in a stochastic model. (g) As a result, both the fatigue limit (defined for 107 loading cycles) and the finite life (high cycle) fatigue S-N curve are obtained statistically. (h) At various analysis steps, parametric equations have been developed which allow for analytical calculations instead of complete stochastic analyses based on finite elements which are unrealistic even at present. (i) The method has been validated with a large number of S-N curves including two materials, three weldment types with two geometries, each referring to differnt manufacturing technologies and the as-welded and stressrelieved state. (j) Althrough not finally solved, an extended discussion is provided on the issue of welding residual stresses including their redistribution under cyclic loading. (k) A number of simplifications is proposed at lower analyses levels which, however, partly lack complete validation by now.
This book provides a comprehensive and thorough guide to those readers who are lost in the often-confusing context of weld fatigue. It presents straightforward information on the fracture mechanics and material background of weld fatigue, starting with fatigue crack initiation and short cracks, before moving on to long cracks, crack closure, crack growth and threshold, residual stress, stress concentration, the stress intensity factor, J-integral, multiple cracks, weld geometries and defects, microstructural parameters including HAZ, and cyclic stress-strain behavior. The book treats all of these essential and mutually interacting parameters using a unique form of analysis.
Der Vortrag behandelt in grundsätzlicher weise die Anwendung bruchmechanischer Methoden auf die rechnerische Ermittlung der Wöhlerkurve. Dabei werden die Besonderheiten des Kurzrisswachstums (Notwendigkeit der elastisch-plastischen Beschreibung der zyklischen Rissspitzenbelastung, gradueller Aufbau des Rissschlißphänomens) ebenso diskutiert wie das Problem des Mehrfachrissewachstums und Rissarrest. Die Ausführungen werden an einem Beispiel illustriert.
The presentation provides a discussion and damage tolerant assessment of metallic AM components. In the focus are problems of the determination of representative material data, the effect of material defects and residual stresses. Starting with the actual state-of-the-art in the field, options and possibilities of a damage tolerant design for AM are discussed.
Der Vortrag thematisiert die Behandlung von Schweißeigenspannungen bei der Auslegung geschweißter Bauteile. Ausgehend von Fragen der Klassifizierung unterschiedlicher Typen von Eigenspannungen wird auf Fragen der Behandlung von Primär- und Sekundärspannungen, der Ermittlung und Aussagefähigkeit von Eigenspannungs-Tiefen-Profilen und der Stabilität der Eigenspannungen bei zyklischer Beanspruchung eingegangen. Neben der Auslegung auf Bruch wird die Beschreibung der Ermüdungsrissausbreitung bei Vorhandensein von Eigenspannungen diskutiert, wobei neben der klassischen Langrissbruchmechanik auch Besonderheiten der Kurzrissbruchmechanik angesprochen werden.
The evaluation of cladding integrity is a major issue to be demonstrated in Germany for extended interim storage periods up to 100 years and subsequent transportation considering operational and accidental conditions with respect to reactor operation, cask drying and dry interim storage. The chemical reaction between the zirconium fuel cladding and the cooling water in water-cooled reactors produces hydrogen and zirconium oxide. Hydrogen diffuses into the cladding and precipitates as zirconium hydrides when the solubility limit is reached, preferably oriented in hoop direction. At high temperatures during vacuum drying procedures, the hydrides can dissolve. Over a succeeding period of slow cooling with existing hoop stress the hydrides precipitate again, but partly reoriented along the radial direction of the cladding. This change of microstructure in combination with a decreasing temperature (0.5...2 K/year) during (extended) interim storage and additional mechanical load by handling procedures or under accident conditions could lead to a potential cladding embrittlement and consequently increased failure probability. The current research project BRUZL (Fracture mechanical analysis of spent fuel claddings under long-term dry interim storage conditions) has been launched by BAM to investigate potential sudden brittle failure of spent fuel claddings at small deformation under long-term dry interim storage conditions and is presented.
The safety evaluation of cask components made of ductile cast iron includes investigations to prevent brittle fracture. Generally, ductile cast iron is endangered by brittle fracture especially at low temperatures (down to -40°C) and in combination with existing crack-like material defects. An applicable method is the assessment of fracture resistance using fracture mechanics according to the IAEA guidelines. The approach is based on the prevention of fracture initiation. For application of these principles for drop loads, account must be taken both of dynamic stresses within the component and dynamic material behavior. Basically, the dynamic stress intensity factor of postulated pre-existing crack-like defects is compared with the dynamic fracture toughness of the material. Applicable numerical and experimental methods for the safety assessment of cask components are demonstrated for the case of an artificially pre-cracked cylindrical cast iron cask which undergoes dynamic loading conditions as result of the hard impact between the cask and a concrete target. The proposed evaluation procedure is a combination of numerical and experimental steps. Exemplarily, the calculated stress intensity factor is compared with measured fracture toughness values from single edge notched bending specimens.
The characterization of spent fuel and radioactive waste is essential in the evaluation of the ability of these materials to meet acceptance criteria. Prior to determining a method for spent fuel characterization, it is necessary to identify the type of data required to support safety and other analyses for the storage, transportation and final disposal of spent fuel. BAM’s understanding and capabilities in the field of spent fuel characterization are presented for the scope of a coordinated research project on the topic.
Embrittlement of spent fuel claddings during long-term dry interim storage - Current approach at BAM
(2019)
The integrity of fuel rods and cladding tubes must be demonstrated throughout the dry interim storage of spent nuclear fuel in Germany. For at least a relevant number of casks, an extension of interim storage between 40 and 100 years is foreseeable. The drying procedure for the fuel rods in conjunction with the thermomechanical storage conditions may change the microstructure of the cladding tubes and lead to their possible embrittlement. The failure probability might increase under mechanical load by handling procedures (transport after storage) on potentially embrittled cladding tubes of fuel rods especially at low temperatures after long-term storage. Results of ring compression tests on unirradiated pre-hydrided as well as irradiated samples with radial hydrides are investigated by finite element analyses to be able to describe the failure process and to identify failure criteria.
In order to demonstrate the safety of both spent fuel and the storage system, a good understanding of the processes that might cause deterioration is required. The International Atomic Energy Agency (IAEA) continued the coordinated research on Spent Fuel Performance Assessment and Research (SPAR) into a fourth phase starting in 2015 to evaluate fuel and materials performance under wet and dry storage and to assess the impact of interim storage on associated spent fuel management activities (such as handling and transport). BAM’s understanding and experiences in the field of long-term storage of spent fuel and especially spent fuel characterization are presented to assist the preparation of the final project report.
Embrittlement of spent fuel claddings during long-term dry interim storage - Current approach at BAM
(2019)
In this presentation, the actual situation of long-term dry interim storage of spent nuclear fuel in Germany is reported. An extension of the interim storage period between 40 and 100 years for at least a relevant number of casks is foreseeable. To demonstrate the integrity of fuel rods and cladding tubes throughout the extended dry interim storage, a potential cladding embrittlement should be investigated. The current approach at BAM is a research project on experimental and numerical investigations of sudden failure of unirradiated pre-hydrided cladding tubes after hydride reorientation at small deformation under Ring Compression Test conditions. A fracture mechanics based failure analysis and suggested failure criteria for a potential brittle failure of spent fuel claddings after long-term dry interim storage under mechanical loads are discussed.
A reliable finite element analysis presupposes a qualified model of the object to be analyzed. The finite element mesh density may significantly vary throughout a model. A transition between dissimilar meshes can be accomplished by a gradual change of element size or by an interface with constraint conditions. Some issues may arise from such mesh transitions. Generally, a finer mesh can transmit signals of higher frequency than a coarser mesh. Stress wave propagation through the model could be affected by the transition region or the artificially induced interface. Stress waves generated within the fine mesh could be partly encapsulated by the surrounding coarse mesh. Therefore poor mesh transitions could result in reflections or shape changes of stress waves. A thin rod is investigated to demonstrate the effects.
This study supports the development of the ASME Guidance Document "Use of Explicit Finite Element Analysis for the Evaluation of Nuclear Transport and Storage Packages in Energy-Limited Impact Events".
The current research project BRUZL (Fracture mechanical analysis of spent fuel claddings during long-term dry interim storage) is presented. General aim of the project is the development of methods for risk assessment and identification of boundary conditions to prevent potential sudden brittle failure of spent fuel claddings at small deformation during long-term dry interim storage and subsequent transportation. The project is funded by the Federal Ministry for Economic Affairs and Energy (BMWi) under contract no. 1501561.
The safety evaluation of cask components made of ductile cast iron includes investigations to prevent brittle fracture. Generally, ductile cast iron is endangered by brittle fracture especially at low temperatures (down to -40°C) and in combination with existing crack-like material defects. An applicable method is the assessment of fracture resistance using fracture mechanics according to the IAEA guidelines. The approach is based on the prevention of fracture initiation. For application of these principles for drop loads, account must be taken both of dynamic stresses within the component and dynamic material behavior. Basically, the dynamic stress intensity factor of postulated pre-existing crack-like defects is compared with the dynamic fracture toughness of the material. Applicable numerical and experimental methods for the safety assessment of cask components are demonstrated for the case of an artificially pre-cracked cylindrical cast iron cask which undergoes dynamic loading conditions as result of the hard impact between the cask and a concrete target. The proposed evaluation procedure is a combination of numerical and experimental steps. Exemplarily, the calculated stress intensity factor is compared with measured fracture toughness values from single edge notched bending specimens.
The evaluation of cladding integrity is a major issue to be demonstrated in Germany for extended interim storage periods up to 100 years and subsequent transportation considering operational and accidental conditions with respect to reactor operation, cask drying and dry interim storage. The chemical reaction between the zirconium fuel cladding and the cooling water in water-cooled reactors produces hydrogen and zirconium oxide. Hydrogen diffuses into the cladding and precipitates as zirconium hydrides when the solubility limit is reached, preferably oriented in hoop direction. At high temperatures during vacuum drying procedures, the hydrides can dissolve. Over a succeeding period of slow cooling with existing hoop stress the hydrides precipitate again, but partly reoriented along the radial direction of the cladding. This change of microstructure in combination with a decreasing temperature (0.5...2 K/year) during (extended) interim storage and additional mechanical load by handling procedures or under accident conditions could lead to a potential cladding embrittlement and consequently increased failure probability. The current research project BRUZL (Fracture mechanical analysis of spent fuel claddings under long-term dry interim storage conditions) has been launched by BAM to investigate potential sudden brittle failure of spent fuel claddings at small deformation under long-term dry interim storage conditions and is presented.
Spherical mesoporous bioactive glasses in the silicon dioxide (SiO2)-phosphorus pentoxide (P2O5)–calcium oxide (CaO) system with a high specific surface area of up to 300m2/g and a medium pore radius of 4 nm were synthesized by using a simple one-pot surfactant-assisted sol–gel synthesis method followed by calcination at 500–700°C. The authors were able to control the particle properties by varying synthesis parameters to achieve microscale powders with spherical morphology and a particle size of around 5–10 mm by employing one structure-directing agent. Due to a high Calcium oxide content of 33·6mol% and a phosphorus pentoxide content of 4·0mol%, the powder showed very good bioactivity up to 7 d of immersion in simulated Body fluid. The resulting microspheres are promising materials for a variety of life science applications, as further processing – for example, granulation – is unnecessary. Microspheres can be applied as materials for powder-based additive manufacturing or in stable suspensions for drug release, in bone cements or fillers.
In diesem Verbundvorhaben werden standardisierte Messverfahren für hybride Gemische erarbeitet, die der Bestimmung sicherheitstechnischer Kenngrößen des Explosionsschutzes dienen. Unter einem hybriden Gemisch wird dabei ein mehrphasiges System aus Brenngas oder brennbarem Dampf, sowie Luft und brennbarem Staub verstanden. Die Veröffentlichung der Ergebnisse erfolgt in einem Abschlussbericht und als DIN-Spezifikation (DIN SPEC). Diese DIN SPEC versetzt Prüfinstitute und Industrie in die Lage, Explosionsgefahren beim Betrieb technischer Anlagen mit hybriden Gemischen einzuschätzen und damit Prozesse sowohl sicherer als auch effizienter zu steuern. Dieses Projekt wird im Rahmen des WIPANOProgramms (Wissens- und Technologietransfer durch Patente und Normen) vom BMWi gefördert.
In this joint project, standardized measurement methods for hybrid
mixtures are developed, which serve to determine safety
characteristics for explosion protection.
A hybrid mixture is a multi-phase System consisting of fuel gas or
vapor, as well as air and flammable dust. This combination can occur
for instance in drying processes or during heterogenous reaction
processes.
In diesem Verbundvorhaben werden standardisierte Messverfahren für hybride Gemische erarbeitet, die der Bestimmung sicherheitstechnischer Kenngrößen des Explosionsschutzes dienen. Unter einem hybriden Gemisch wird dabei ein mehrphasiges System aus Brenngas oder brennbarem Dampf, sowie Luft und brennbarem Staub verstanden. Die Veröffentlichung der Ergebnisse erfolgt in einem Abschlussbericht und als DIN-Spezifikation (DIN SPEC). Diese DIN SPEC versetzt Prüfinstitute und Industrie in die Lage, Explosionsgefahren beim Betrieb technischer Anlagen mit hybriden Gemischen einzuschätzen und damit Prozesse sowohl sicherer als auch effizienter zu steuern. Dieses Projekt wird im Rahmen des WIPANOProgramms (Wissens- und Technologietransfer durch Patente und Normen) vom BMWi gefördert.
At the Bundesanstalt für Materialforschung und -prüfung (BAM) in Division 3.4 Safety of Storage Containers, one of our tasks is to evaluate the safety of containers designed for disposal of low and intermediate radioactive waste. As such containers might be transported before and stored until disposal, safe enclosure of the radioactive inventory is important for this time span.
Elastomer O-rings are widely used as barrier seals in these containers. Thus, as for many other applications, an understanding of the practical effects of ageing degradation on elastomer seals during long-term exposure is mandatory for predicting the lifetime of such components. According to a long-term test programme on three kinds of rubbers (EPDM and FKM (relevant for application), HNBR (for comparison)), over several years we have studied the degradation and the change of mechanical properties (e.g. hardness, strain at break) at four different ageing temperatures (75 °C, 100 °C, 125 °C and 150 °C) as well as the change of sealing properties. Continuous and intermittent compression stress relaxation (CSR) measurements were performed in order to investigate the respective contribution of crosslinking and chain scission to the observed degradation effects. Thus, the degradation kinetics and mechanisms could be resolved more clearly. For assessing the seal performance, compression set (CS) and leakage rate measurements were conducted. The experimental results showed that the O-rings remained leak-tight under purely static conditions even when CSR, CS and mechanical properties already indicated far advanced degradation. For this reason, a modified leakage test involving a small and rapid partial decompression of the seal was developed that enabled determining an end-of-lifetime criterion for O-rings with a safety margin for thermal shrinkage and vibrations.
Nowadays, different nanoparticles have been developed for commercial applications. However, since data on toxicity are barely available, their increasing application in cosmetic products, food and their release in the environment might cause severe problems. Since a range of physical, chemical, and biological characteristics of NPs are closely related to particle size and surface functionalization, precise separation and surface groups quantification is essential to acquire an in-depth understanding of their properties.
In this work, the performance of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) for the separation of nanoparticles (NPs) with different sizes, coatings, and coating densities was investigated and optimized.
For the first time, a two-dimensional off-line hyphenation of both techniques (AF4-CE) was developed. The results clearly demonstrated, that AF4-CE hyphenation can significantly improve the separation resolution and reduce the peak broadening in CE. Also, for the first time, CE was employed to determine the coating density of NPs and the results were in good agreement with the values acquired with conductometric titration.
The successful off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) for Separation of nanoparticles (NPs) with different surface coatings was shown.
Two mixtures of polystyrene nanoparticles (PS-NPs) with comparable core sizes (20 nm and 50 nm) but different coatings (no coating/carboxyl-coated) were studied. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional off-line coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots and can obviouly improve separation resolution.
Polymeric membranes represent a low-cost, energy efficient solution for gas separation. Recently polymers of intrinsic microporosity (PIMs) have emerged as prestigious membrane materials featuring a large concentration of pores smaller than 1 nm, a BET surface area larger than 700 m2/g and high gas permeability and selectivity. Unusual chain structure combining rigid segments with sites of contortion gives rise to the intrinsic microporosity. However, this novel class of glassy polymers are prone to pronounced physical aging. The initial microporous structures approach a denser state via local small scale fluctuataions, leading to a dramatic reduction in the gas permeabilities. For the first time, dielectric relaxation spectroscopy with state-of-the-art high-resolution analyzers was employed to investigate three representative PIMs with a systematic change in chain rigidity: PIM-EA-TB 〉 PIM-1 〉 PIM-MDPH-TB. The molecular mobility, the charge transport and their response upon heating (aging) in the polymers were measured in a broad temperature range through isothermal frequency scans during different heating / cooling cycles. Multiple dielectric processes following Arrhenius behavior were observed for the investigated polymers. Local fluctuations, Maxwell-Wagner-Sillars (MWS) polarization and structural relaxation phenomena were discussed and attempted to be correlated with the structural features of PIMs. Moreover, all PIMs showed conductivity in the glassy state. The significant increase in the conductivity with increasing temperature far below the glass transition temperature of PIMs is explained in terms of the loosely packed microporous structure and the formation of local intermolecular agglomerates due to interaction of π-electrons in aromatic moieties of the polymer backbone.
High performance polymers of intrinsic microporosity (PIMs) have emerged as novel materials with broad applications from gas separation to electronic devices. Sufficiently rigid, even contorted polymer chains show only limited molecular mobility, therefore undergo inefficient packing and give rise to intrinsic microporosity with pore size generally smaller than 1 nm and BET surface areas larger than 700 m2/g. Further performance optimization and long-term stability of devices incorporating PIMs rely on our understanding of structure-processing-property relationships and physical aging, in which glass transition plays a key role. Up to now no glass transition temperature (Tg) of PIMs could be detected with conventional thermal analysis techniques before degradation. Decoupling the time scales responsible for the glass transition and the thermal decomposition is a reliable strategy to overcome this. This was achieved by employing fast scanning calorimetry (FSC) based on a chip sensor, which is capable to heat and cool a small sample (ng-range) with ultrafast rates of several ten thousand K/s. FSC provides definitive evidence of glass transition of a series of PIMs with a special consideration on the chain rigidity. The determined glass transition temperature of these PIMs follows the order of the rigidity of their backbone structures. FSC provides the first clear-cut experimental evidence of the glass transition of PIM-EA-TB with a Tg of 663 K, PIM-1 of 644 K and PIM-DMDPH-TB of 630 K at a heating rate of 1Χ104 K/s. Local fluctuations are featured in glass transition of highly rigid PIMs. As conformational changes are prevented by the backbone rigidity, the glass transition must rather be assigned to local small scale fluctuations.
In this study, the molecular dynamics of a series of dipole functionalized triphenylene-based discotics, forming a columnar mesophase, were investigated by broadband dielectric spectroscopy (BDS). In addition to conductivity and localized dynamics, glassy dynamics were also observed. At higher temperatures an α1-processes and at low temperatures an α2 processes were detected having a completely different temperature dependence of its relaxation times. Different molecular assignments of α1- and α2-processes are suggested. The phase behavior of the material was explored under helium purge down to 100 K by differential scanning calorimetry (DSC). Besides the phase transition temperatures and enthalpies, one or two thermal glass transitions were found for all the materials. Moreover, the glassy dynamics were further investigated by Flash DSC, which is a chip-based calorimetry technique allowing for fast heating and cooling rates as high as 10000K/s.
The elemental analysis of seawater is often critical to the understanding of marine chemistry, marine geochemistry, and the deep-sea ecosystems. Laser-induced breakdown spectroscopy (LIBS) with the advantage of rapid multi-elements detection, has a great potential for in-situ elemental analysis of seawater. In practice, it is crucial to create a compact, low cost and power saving instrument for the long-term deep-sea observation. A recently appeared diode-pumped solid-state (DPSS) laser seems to be a promising candidate as it is both compact and robust. Additionally, its high repetition rate up to hundreds of kHz can provide a considerable throughput for LIBS analysis. However, the DPSS lasers operate at moderate pulse energies, usually less than one mJ, which cannot sustain stable breakdowns in bulk water. To ensure stable laser-induced plasmas underwater with such a μJ-DPSS laser, we introduced an ultrasound source to assist the breakdown process. The phase interface and mass flow generated by the near-field ultrasound can greatly reduce the breakdown threshold and enhance element-specific emissions. Meanwhile, the high repetition-rate pulses can also improve the breakdown probability and generate unique emission lines originated from the water molecule. We further demonstrate that the high repetition-rate DPSS laser combined with the Echelle spectrometer can provide effective quantitative analysis for metal elements in bulk water.
The elemental analysis of seawater is often critical to the understanding of marinechemistry, marine geochemistry, and the deep-sea ecosystems. Laser-induced breakdownspectroscopy (LIBS) with the advantage of rapid multi-elements detection, has a greatpotential for in-situ elemental analysis of seawater. In practice, it is crucial to create acompact, low cost and power saving instrument for the long-term deep-sea observation. Arecently appeared diode-pumped solid-state (DPSS) laser seems to be a promising candidateas it is both compact and robust. Additionally, its high repetition rate up to hundreds of kHzcan provide a considerable throughput for LIBS analysis. However, the DPSS lasers operateat moderate pulse energies, usually less than one mJ, which cannot sustain stablebreakdowns in bulk water. To ensure stable laser-induced plasmas underwater with such aμJ-DPSS laser, we introduced an ultrasound source to assist the breakdown process. Thephase interface and mass flow generated by the near-field ultrasound can greatly reduce thebreakdown threshold and enhance element-specific emissions. Meanwhile, the highrepetition-rate pulses can also improve the breakdown probability and generate uniqueemission lines originated from the water molecule. We further demonstrate that the highrepetition-rate DPSS laser combined with the Echelle spectrometer can provide effectivequantitative analysis for metal elements in bulk water.
Non-linear optical emitters are promising materials for energy applications and biotechnologies. Solid-state multi-band emitters like lanthanide doped up-conversion nanoparticles (UCNPs) show excellent photostability, are excitable in the near infrared (NIR), and show emission bands from the UV to SWIR spectral regions. The optical properties of these materials strongly depend on the excitation power density, i.e., the number of photons absorbed per time interval. The upconversion (ΦUC) and downshifting quantum efficiencies (ΦDS) of these materials, the excitation power dependent population, and the deactivation dynamics are influenced by nanoparticle architecture, doping concentration, and the microenvironment. We studied the fundamental changes of the luminescence properties of ß-NaYF4 UCNPs doped with Yb3+ and Er3+ depending on size, different surroundings such as aqueous and organic media, and different surface chemistries. We obtained further insights into shelling procedures, FRET optimization, influence of doping concentration, and advantages of different sensitizer ions.
Tanks sind für normale Beförderungsbedingungen gebaut und zugelassen! Tankkörper müssen nach Normen (siehe 6.8.2.6 RID/ADR) oder nach einem von der zuständigen Behörde anerkannten technischen Regelwerk entworfen und gebaut werden Schweißverbindungen müssen nach Regeln der Technik ausgeführt werden. Unterdruck im Tank ist zu berücksichtigen (Berechnung, Vakuumventil). Beständigkeit – Gefahrgut darf mit Tankwerkstoff nicht gefährlich reagieren oder die Werkstoffe merklich schwächen!
Vor nun 30 Jahren, im Jahre 1989, wurde die erste Zulassung für eine Kunststoffdichtungsbahn (KDB) von der BAM auf der Grundlage des Niedersächsischen Dichtungserlasses“ erteilt. Vor ungefähr 10 Jahren wurde die BAM mit dem Erscheinen der Deponieverordnung (DepV) mit der Zulassung von Geokunststoffen, Polymeren und Dichtungskontrollsystemen beauftragt. Wir möchten dies zum Anlass nehmen, an dieser Stelle den viele ehrenamtlichen Experten des Fachbeirats und seiner Arbeitsgruppen für ihren Einsatz und die Unterstützung zu danken.
Darüber hinaus soll über aktuelle Arbeitsthemen und Entwicklungen im Fachbeirat berichtet werden. So wurde in einer Sondersitzung des Fachbeirats über die Entlassung aus der Nachsorgephase beim Einsatz von Geokunststoffprodukten in Böschungen diskutiert. Die Unterarbeitsgruppe Fremdüberwachung in der Produktion hat getagt. Darüber hinaus werden Änderungen in den Zulassungsrichtlinien für Kunststoffdichtungsbahnen, Kunststoff-Dränelemente und Geogitter kurz vorgestellt.
Vor nun 30 Jahren, im Jahre 1989, wurde die erste Zulassung für eine Kunststoffdichtungsbahn (KDB) von der BAM auf der Grundlage des „Niedersächsischen Dichtungserlasses“ erteilt. Vor ungefähr 10 Jahren wurde die BAM mit dem Erscheinen der Deponieverordnung (DepV) mit der Zulassung von Geokunststoffen, Polymeren und Dichtungskontrollsystemen beauftragt. Wir möchten dies zum Anlass nehmen, an dieser Stelle den viele ehrenamtlichen Experten des Fachbeirats und seiner Arbeitsgruppen für ihren Einsatz und die Unterstützung zu danken.
Darüber hinaus soll über aktuelle Arbeitsthemen und Entwicklungen im Fachbeirat berichtet werden. So wurde in einer Sondersitzung des Fachbeirats über die Entlassung aus der Nachsorgephase beim Einsatz von Geokunststoffprodukten in Böschungen diskutiert. Die Unterarbeitsgruppe Fremdüberwachung in der Produktion hat getagt. Darüber hinaus werden Änderungen in den Zulassungsrichtlinien für Kunststoffdichtungsbahnen, Kunststoff-Dränelemente und Geogitter kurz vorgestellt.
Vor nun 30 Jahren im Jahre 1989 wurde die erste Zulassung für eine Kunststoffdichtungsbahn von der BAM auf der Grundlage des „Niedersächsischen Dichtungserlasses“ erteilt. Vor ungefähr 10 Jahren wurde die BAM mit dem Erscheinen der Deponieverordnung (DepV) mit der Zulassung von Geokunststoffen, Polymeren und Dichtungskontrollsystemen beauftragt. Wir möchten dies zum Anlass nehmen, an dieser Stelle den viele ehrenamtlichen Experten des Fachbeirats und seiner Arbeitsgruppen für ihren Einsatz und die Unterstützung zu danken.
Darüber hinaus soll über aktuelle Arbeitsthemen und Entwicklungen im Fachbeirat berichtet werden. So soll in einer Sondersitzung des Fachbeirats über die Entlassung aus der Nachsorgephase beim Einsatz von Geokunststoffprodukten in Böschungen diskutiert werden. Es ist geplant, in einer Unterarbeitsgruppe eine Sitzung über die Fremdüber¬wachung in der Produktion abzuhalten. Darüber hinaus werden Änderungen in den Zulassungsrichtlinien für Kunststoff Dichtungsbahnen und Kunststoff Dränelemente kurz vorgestellt. In der Zwischenzeit wurde auch die abschließende Zulassungsrichtlinie für Geogitter verabschiedet. Neue Fragestellungen sind hier entstanden. Unter welchen Voraussetzungen können Geogitter in Zwischenabdichtungen eingesetzt werden. Bisher können diese Produkte formal nur in Oberflächenabdichtungen eingesetzt werden. Auch auf diese beiden Themen soll im Folgenden in Kürze eingegangen werden.
Vor nun 30 Jahren im Jahre 1989 wurde die erste Zulassung für eine Kunststoffdichtungsbahn von der BAM auf der Grundlage des „Niedersächsischen Dichtungserlasses“ erteilt. Vor ungefähr 10 Jahren wurde die BAM mit dem Erscheinen der Deponieverordnung (DepV) mit der Zulassung von Geokunststoffen, Polymeren und Dichtungskontrollsystemen beauftragt. Wir möchten dies zum Anlass nehmen, an dieser Stelle den viele ehrenamtlichen Experten des Fachbeirats und seiner Arbeitsgruppen für ihren Einsatz und die Unterstützung zu danken.
Darüber hinaus soll über aktuelle Arbeitsthemen und Entwicklungen im Fachbeirat berichtet werden. So soll in einer Sondersitzung des Fachbeirats über die Entlassung aus der Nachsorgephase beim Einsatz von Geokunststoffprodukten in Böschungen diskutiert werden. Es ist geplant, in einer Unterarbeitsgruppe eine Sitzung über die Fremdüber¬wachung in der Produktion abzuhalten. Darüber hinaus werden Änderungen in den Zulassungsrichtlinien für Kunststoff Dichtungsbahnen und Kunststoff Dränelemente kurz vorgestellt. In der Zwischenzeit wurde auch die abschließende Zulassungsrichtlinie für Geogitter verabschiedet. Neue Fragestellungen sind hier entstanden. Unter welchen Voraussetzungen können Geogitter in Zwischenabdichtungen eingesetzt werden. Bisher können diese Produkte formal nur in Oberflächenabdichtungen eingesetzt werden. Auch auf diese beiden Themen soll im Folgenden in Kürze eingegangen werden.
By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localize damage was examined. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localization responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed. In this attempt, the systematic influences such as residual stress are kept as low as possible.
The present work is intended to make a contribution to the monitoring of civil engineering structures. The detection of damage to structures is based on the evaluation of spatially and temporally distributed hybrid measurements. The acquired data can be evaluated purely geometrically or physically. It is preferable to do the latter, since the cause of damage can be determined by means of geometrical-physical laws in order to be able to intervene in time and ensure the further use of the structures. For this reason, the continuum mechanical field equations in conjunction with the finite element method and hybrid measurements are combined into a single evaluation method by the adjustment calculation. This results in two challenges.
The first task deals with the relationship between the finite element method and the method of least squares. The finite element method solves certain problem classes, which are described by a system of elliptical partial differential equations. Whereas the method of least squares solves another class of problems, which is formulated as an overdetermined system of equations. The striking similarity between both methods is known since many decades. However, it remains unresolved why this resemblance exists. The contribution is to clarify this by examining the variational calculus, especially with regard to its methodological procedure. Although the well-known Gauss-Markov model within the method of least squares and the finite element method solve inherently different problem classes, it is shown that both methods can be derived by following the same methodological steps of the variational calculus. From a methodical viewpoint, this implies that both methods are not only similar, but actually the same. In addition, it is pointed out where a possible cross-connection to other methods exists.
The second task introduces a Measurement- and Model-based Structural Analysis (MeMoS) by integrating the finite element method into the adjustment calculation. It is shown in numerical examinations how this integrated analysis can be used for parameter identification of simple as well as arbitrarily shaped structural components. Based on this, it is examined with which observation types, with which precision and at which location of the structure these measurements must be carried out in order to determine the material parameters as precisely as possible. This serves to determine an optimal and economic measurement set-up. With this integrated analysis, a substitute model of a geometrically complex structure can also be determined. The issue of the detection and localisation of damage within a structure is studied by means of this structural analysis. The Measurement and Model-based Structural Analysis is validated using two different test setups, an aluminum model bridge and a bending beam.
The present work is intended to make a contribution to the monitoring of civil engineering structures. The detection of damage to structures is based on the evaluation of spatially and temporally distributed hybrid measurements. The acquired data can be evaluated purely geometrically or physically. It is preferable to do the latter, since the cause of damage can be determined by means of geometrical-physical laws in order to be able to intervene in time and ensure the further use of the structures. For this reason, the continuum mechanical field equations in conjunction with the finite element method and hybrid measurements are combined into a single evaluation method by the adjustment calculation. This results in two challenges.
The first task deals with the relationship between the finite element method and the method of least squares. The finite element method solves certain problem classes, which are described by a system of elliptical partial differential equations. Whereas the method of least squares solves another class of problems, which is formulated as an overdetermined system of equations. The striking similarity between both methods is known since many decades. However, it remains unresolved why this resemblance exists. The contribution is to clarify this by examining the variational calculus, especially with regard to its methodological procedure. Although the well-known Gauss-Markov model within the method of least squares and the finite element method solve inherently different problem classes, it is shown that both methods can be derived by following the same methodological steps of the variational calculus. From a methodical viewpoint, this implies that both methods are not only similar, but actually the same. In addition, it is pointed out where a possible cross-connection to other methods exists.
The second task introduces a Measurement- and Model-based Structural Analysis (MeMoS) by integrating the finite element method into the adjustment calculation. It is shown in numerical examinations how this integrated analysis can be used for parameter identification of simple as well as arbitrarily shaped structural components. Based on this, it is examined with which observation types, with which precision and at which location of the structure these measurements must be carried out in order to determine the material parameters as precisely as possible. This serves to determine an optimal and economic measurement set-up. With this integrated analysis, a substitute model of a geometrically complex structure can also be determined. The issue of the detection and localisation of damage within a structure is studied by means of this structural analysis. The Measurement and Model-based Structural Analysis is validated using two different test setups, an aluminum model bridge and a bending beam.
By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localize damage was examined. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localization responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed. In this attempt, the systematic influences such as residual stress are kept as low as possible.
The sales of niobium carbide (NbC) have grown in the last years, but NbC is still a hidden carbide and mainly used as grain growth inhibitor in hard metals. In the present work it was shown that the progress in the key properties, like HV30, KIC and strength, followed by machining and tribological results of the respective NbC grades.
For the purpose of increasing payload and reduce freight cost, lightweight composite tank containers used for Transportation have been progressively developed during the last years. Compared to conventionally produced cylindrical steel tanks, the fiber-reinforced solutions allow greater flexibility in the tank design. Despite a number of further material-related benefits of fiber-reinforced composites as non-conductive and non-magnetic behavior as well as corrosion resistance and high strength, the optimization of their thermal degradation properties during combustion is still a challenge. To improve the fire performance of lightweight composite containers, special intumescent fire protection coatings can be applied onto the outside tank surface. This paper presents fire tests on glass-fiber-reinforced plastic transport tanks with complex geometries sheltered with different surface-applied fire protection systems. To evaluate the fire resistance of the tank structures, a fiber optic monitoring system was developed. This system is based on distributed temperature measurements using high-Resolution optical backscatter reflectometry and pointwise reference measurements using fiber Bragg gratings. Thereby, all the fiber optic sensors were directly integrated in the composite layer structure of the tanks. The focus of the presented work is on the demonstration of capability of fiber optic monitoring system in such high-temperature application. Moreover, the fiber optic measurements provide new insights into the efficiency of intumescent coating applied for fire protection of fiber-reinforced plastic transport tanks.
We present our research on the development of a Brillouin optical frequency-domain analysis (BOFDA) using a perfluorinated graded-index polymer optical fiber (PFGI-POF) as a sensing fiber. The described works include investigations both on the selection of the setup components with respect to mode coupling effects and on the impact of the humidity cross-sensitivity. The suitability of the developed POF-based BOFDA is proved by a distributed measurement on an 86 m long PFGI-POF recorded with the spatial resolution of 6 m.
Smart geosynthetics with embedded optical fibers as distributed sensors provide solutions both for applications in geotechnical engineering and for cost-effective monitoring of critical infrastructures. The incorporation of glass or polymer optical fibers (GOFs or POFs) in geotextiles and geogrids allows early detection of mechanical deformations, temperature and humidity. This paper presents selected examples of smart geosynthetics based on Brillouin and Rayleigh scattering effects in incorporated fiber optic sensors for monitoring of large geotechnical structures like dikes, dams, railways, embankments or slopes. The focus of the presented work is on real field tests of measurement capability with respect to the chosen measurement principle and used fiber type.
In the present study, the impact of static traffic loading on the slight deflection effects in the concrete structure of an existing bridge has been investigated using distributed fiber optic sensors. In the face of increasing traffic density and severe traffic loading, the results of the load tests on the Amsterdam bridge 705 make an important contribution to the understanding of its structural behavior. The concept of the static loading was based on the use of two 36-ton trucks stopped on the bridge at multiple pre-determined locations. The load applied in this way led to location-dependent small deflection effects recorded as longitudinal strain of the sensing fiber embedded at the underside of the bridge. The measurements were performed with a commercially-available solution based on Tunable Wavelength Coherent Optical Time Domain Reflectometry with the measurement accuracy in the range of 0.5 µm/m.
In the present study, the impact of static traffic loading on the slight deflection effects in the concrete structure of an existing bridge has been investigated using distributed fiber optic sensors. In the face of increasing traffic density and severe traffic loading, the results of the load tests on the Amsterdam bridge 705 make an important contribution to the understanding of its structural behavior. The concept of the static loading was based on the use of two 36-ton trucks stopped on the bridge at multiple pre-determined locations. The load applied in this way led to location-dependent small deflection effects recorded as longitudinal strain of the sensing fiber embedded at the underside of the bridge. The measurements were performed with a commercially-available solution based on Tunable Wavelength Coherent Optical Time Domain Reflectometry with the measurement accuracy in the range of 0.5 µm/m.
Auf der Grundlage der in DIN EN 61757-2-2:2017 beschriebenen Standardisierungsmethoden wurden in dieser Arbeit wichtige Leistungsparameter von vier kommerziellen Messsystemen zur ortsaufgelösten faseroptischen Erfassung der temperatur- und dehnungsabhängigen Brillouin-Frequenzverschiebung untersucht. Gemäß der oben genannten Norm konzentrierte sich hier die Ermittlungsprüfung auf messtechnische Aspekte reiner Temperaturmessungen. Dabei diente die Ermittlung von einem festgelegten Satz dreier Betriebsverhaltenskenngrößen in Form von quantitativen Angaben des Messfehlers, der Wiederholgenauigkeit sowie der räumlichen Unsicherheit einem Vergleich der getesteten Messsysteme.
Alle faseroptischen Messungen wurden mit einer Faserschleife ausgeführt, d. h. als Sensorkonfiguration der Messfaser wurde eine Schleifenanordnung gewählt. Die Messverfahren der getesteten Messysteme basierten somit auf der Brillouin-optischen Zeit- bzw. Frequenzbereichsanalyse. Die Betriebsverhaltenskenngrößen wurden ferner bei unterschiedlichen Werten zweier messtechnischer Parameter, des Frequenzschrittes und der Mittelungsrate, für Standardeinstellungen der Laserleistungswerte der in die Sensorfaser einzukoppelnden Laserlichtsignale ermittelt. Auf diesem Weg lassen sich relevante Aussagen zur Optimierung der Messgenauigkeiten in Bezug auf Messdauer treffen.
Auf der Grundlage der in DIN EN 61757-2-2:2017 beschriebenen Standardisierungsmethoden wurden in dieser Arbeit wichtige Leistungsparameter von vier kommerziellen Messsystemen zur ortsaufgelösten faseroptischen Erfassung der temperatur- und dehnungsabhängigen Brillouin-Frequenzverschiebung untersucht. Gemäß der oben genannten Norm konzentrierte sich hier die Ermittlungsprüfung auf messtechnische Aspekte reiner Temperaturmessungen. Dabei diente die Ermittlung von einem festgelegten Satz dreier Betriebsverhaltenskenngrößen in Form von quantitativen Angaben des Messfehlers, der Wiederholgenauigkeit sowie der räumlichen Unsicherheit einem Vergleich der getesteten Messsysteme.
Alle faseroptischen Messungen wurden mit einer Faserschleife ausgeführt, d. h. als Sensorkonfiguration der Messfaser wurde eine Schleifenanordnung gewählt. Die Messverfahren der getesteten Messysteme basierten somit auf der Brillouin-optischen Zeit- bzw. Frequenzbereichsanalyse. Die Betriebsverhaltenskenngrößen wurden ferner bei unterschiedlichen Werten zweier messtechnischer Parameter, des Frequenzschrittes und der Mittelungsrate, für Standardeinstellungen der Laserleistungswerte der in die Sensorfaser einzukoppelnden Laserlichtsignale ermittelt. Auf diesem Weg lassen sich relevante Aussagen zur Optimierung der Messgenauigkeiten in Bezug auf Messdauer treffen.
We present our research on the development of a Brillouin optical frequency-domain analysis (BOFDA) using a perfluorinated graded-index polymer optical fiber (PFGI-POF) as a sensing fiber. The described works include investigations both on the selection of the setup components with respect to mode coupling effects and on the impact of the humidity cross-sensitivity. The suitability of the developed POF-based BOFDA is proved by a distributed measurement on an 86 m long PFGI-POF recorded with the spatial resolution of 6 m.
This publication summarizes the work carried out during an IAEA coordinated research project (CRP) on safe and reliabe management of spent nuclear fuel. This work contributes to the overall goal of demonstrating the performance of spent nuclear fuel and related storage systems components over long durations, and facilitates the transfer of this knowledge to Member States. The technical areas addressed by the CRP participants were related to potential degradation mechanisms in metal casks and concrete overpacks, such as stress corrosion cracking; long term integrity and performance of the fuel cladding; thermo-mechanical behaviour of the metal seals; and long term gamma and neutron shielding capability. The participants also considered past and ongoing demonstration programmes. For each technical topic addressed the main conclusions have been drawn, including information on the development of specific monitoring and inspection techniques as well as future opportunities for closing relevant data gaps. A major achievement is also the establishment of a worldwide network of experts working on current research projects to demonstrate the long term performance of spent fuel in dry storage systems.
Spent fuel storage periods well beyond those originally foreseen are a reality. This publication offers several ideas and approaches that may be considered to address the increasingly longer storage times. The aim is to raise awareness, encourage dialogue and provide ideas on how to manage spent fuel. Key messages include the following:
- Delays in reprocessing or disposal could result in spent fuel being stored for 100 years or longer. Safe, secure and effective storage of spent fuel manages fuel degradation while preserving future fuel cycle options.
- Ageing management programmes apply engineering, operations and maintenance actions to ensure safety is maintained during storage, future handling and transport.
- Site selection and facility and equipment design can significantly reduce the risks and costs of spent fuel storage over longer periods.
- Spent fuel storage configurations can be selected to accommodate uncertain storage periods, to facilitate ageing management and to provide flexibility needed to accommodate the uncertainty of future end points, such as reprocessing or disposal.
- By considering multiple licence renewals, regulatory frameworks can be designed to ensure safe storage until an acceptable end point is achieved.
- Safety can be assured by maintaining shielding, containment, decay heat removal and criticality control. Navigating the complexity of societal beliefs and values, as well as political systems, has proven to be a greater challenge for the management of spent fuel than maintaining its safety and security or addressing the technical and economic aspects.
- Sustainable spent fuel management requires policies and strategies to provide a clear, consistent and stable direction because they drive the need for spent fuel storage as well as the available options and timing for achieving an acceptable end point. Unless States address spent fuel reprocessing and disposal on a sufficient scale to accommodate their spent fuel discharges, then storage for longer and longer periods becomes the de facto end point — which is not considered to be consistent with the responsibility to protect human health and the environment.
An effective, periodic licence renewal process can ensure effective ageing management and strong institutional control. Hence, spent fuel can be safely and securely stored for as long as it may be necessary until transport for reprocessing or disposal. However, the risks and costs of storing the growing inventory of spent fuel will continue to increase; and in the absence of an end point, it will eventually become a significant societal burden.
In this presentation, the history and actual situation of the German nuclear waste management policy of spent fuel (SF) and high-level waste (HLW) is reported. Beside the description of the restructuration of responsible authorities and organizations in Germany, the principle of dry interim storage of SF and HLW in dual purpose casks is explained. The need for extended interim storage towards disposal implicates additional challenges for the nuclear waste management strategy in Germany. (Extended)interim storage, subsequent transportation, and final disposal are closely linked. Integrated approaches concerning waste package designs and operations are supposed to be beneficial for the establishment of efficient long-term SF and HLW management strategies. Knowledge management and staff recruiting, education and training during phase out and beyond nuclear power plant operation are major issues.
In der Praxis kommt es immer wieder zu Ausbränden von medizinischen Geräten und industriellen Anlagen mit Sauerstoff. Armaturen und Anlagenteile dürfen deshalb nur dann mit Sauerstoff verwendet werden, wenn sie sicherheitstechnisch für die entsprechenden Betriebsbedingungen geeignet sind. Neben ganz konkreten Anforderungen aus produktspezifischen Normen und Richtlinien, müssen die Prüfungen in vielen Fällen individuell auf die jeweilige Anwendung zugeschnitten werden. Der Vortrag stellt die BAM-Sicherheitsphilosophie hinsichtlich der unterschiedlichen Anforderungen und Möglichkeiten der Beurteilung der Ausbrennsicherheit vor.
In der Praxis kommt es immer wieder zu Ausbränden von medizinischen Geräten und industriellen Anlagen mit Sauerstoff. Armaturen und Anlagenteile dürfen deshalb nur dann mit Sauerstoff verwendet werden, wenn sie sicherheitstechnisch für die entsprechenden Betriebsbedingungen geeignet sind. Neben ganz konkreten Anforderungen aus produktspezifischen Normen und Richtlinien, müssen die Prüfungen in vielen Fällen individuell auf die jeweilige Anwendung zugeschnitten werden. Der Vortrag stellt die BAM-Sicherheitsphilosophie hinsichtlich der unterschiedlichen Anforderungen und Möglichkeiten der Beurteilung der Ausbrennsicherheit vor.
This presentation gives an introduction to the gas-sensitive aerial robots developed at BAM, including various application examples in the field of mobile robot olfaction: gas source localization and gas distribution mapping.
Occupational health is an important topic, especially in industry, where workers are exposed to airborne by-products (e.g., dust particles and gases). Therefore, continuous monitoring of the air quality in industrial environments is crucial to meet safety standards. For practical and economic reasons, high-quality, costly measurements are currently only carried out sparsely, both in time and space, i.e., measurement data are collected in single day campaigns at selected locations only.
Recent developments in sensor technology enable cost-efficient gas monitoring in real-time for long-term intervals. This knowledge of contaminant distribution inside the industrial environment would provide means for better and more economic control of air impurities, e.g., the possibility to regulate the workspace’s ventilation exhaust locations, can reduce the concentration of airborne contaminants by 50%.
This paper describes a concept proposed in the project “Robot-assisted Environmental Monitoring for Air Quality Assessment in Industrial Scenarios“ (RASEM). RASEM aims to bring together the benefits of both – low- and high-cost – measuring technologies: A stationary network of low-cost sensors shall be augmented by mobile units carrying high-quality sensors. Additionally, RASEM will develop procedures and algorithms to map the distribution of gases and particles in industrial environments.
The Motivation of RASEM (Robot-assisted Environmental Monitoring):
Monitoring of the air quality in industrial environments is inevitable to meet safety Standards.
Because of economic and practical reasons, measurements are carried out sparsely in terms of time and space.
Newest developments on the field of low cost sensor technology enable cost efficient long term monitoring of gases and dust
Es wird ein alternatives Verfahren zur schnellen zweidimensionalen Analyse der chemischen Zusammensetzung von Baustoffen vorgestellt. Dieses beruht auf der Kombination des Abtrags einer geringen Materialmenge durch einen gepulsten Laser, der Plasmaerzeugung und der Analyse der Lichtemission des Plasmas mittels optischer Spektroskopie. Es können prinzipiell alle Elemente gleichzeitig nachgewiesen werden. Damit ist es möglich einerseits Informationen über den Baustoff an sich als auch über den Eintrag potentiell schädigender Elemente (z. B. Cl, C, Na, K, S) zu gewinnen. Das Verfahren kann automatisiert im Labor oder als mobile Version direkt vor Ort eingesetzt werden. Es liefert zweidimensionale Bilder der Elementverteilung in Echtzeit. Es kann ohne große Probenvorbereitung z. B. direkt an der Querschnittsfläche eines Bohrkernes gemessen werden. Die Messung dauert nur wenige Minuten. Das Prinzip der Messung, die Vor- und die Nachteile, sowie die verfügbare Gerätetechnik für den Einsatz im Labor oder direkt am Bauwerk werden vorgestellt. Abschließend werden praktische Beispiele für die Anwendung des LIBS-Verfahrens zur Erfassung des Chlorid-Eintrages, der Karbonatisierung und der Verteilung von Schwefel präsentiert.
The application of a LIBS system is presented. A diode-pumped low energy laser (3 mJ, 1.5 ns, 100 Hz) and a compact NIR spectrometer are used. A scanner allows the two-dimensional element mapping. For the quantitative analysis calibration of the system is carried out with reference samples in a concentration range of chlorine of 0.05 wt.% to 2.5 wt.%. To determine the 2D distribution of harmful elements (Cl, C), concrete cores were drilled, split and analyzed directly. By comparing the chloride ingress and the carbonation, the interaction of both processes can be visualized in one measurement that takes less than 10 minutes with a drill core of 50 mm x 100 mm. Results obtained were compared and verified with standard measurements.