Post-testing measurement of freely movable and diffusible hydrogen in context of WEC formation at cylindrical roller thrust bearings from 100Cr6

Sub-surface crack networks in areas of altered microstructure are a common cause for bearing failures. Due to its appearance under light microscopy, the damage pattern is referred to as White Etching Cracks (WEC). The root causes leading to the formation of WEC are still under debate. Nevertheless, it has already been shown that atomic hydrogen can have an accelerating effect on the formation and propagation of WEC. In addition to hydrogen pre-charging, hydrogen can be released and absorbed during rolling/sliding due to the decomposing of the lubricant and water. The current work focuses on the analysis of the hydrogen content of cylindrical roller thrust bearings after testing in a FE8 type test rig using two different lubricants. Within the framework of this work, two different hydrogen analysis methods were used and assessed regarding their applicability. The results show that the so-called Hydrogen Collecting Analysis (HCA) is more suitable to investigate the correlation between lubricant chemistry and hydrogen content in the test bearings than the Local Hydrogen Analysis (LHA). The measurements with the HCA show a continuously increasing freely movable and diffusible hydrogen content under tribological conditions, which leads to the formation of WEC. Comparative tests with an oil without hydrogen showed that the tendency of the system to fail as a result of WEC can be reduced by using a lubricant without hydride compounds.

Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident in the APR1400 Containment Using a Multi-Dimensional Hydrogen Analysis System

Korea Atomic Energy Research Institute (KAERI) established a multi-dimensional hydrogen analysis system to evaluate hydrogen release, distribution, and combustion in the containment of a Nuclear Power Plant (NPP), using MAAP, GASFLOW, and COM3D. In particular, KAERI developed an analysis methodology for a hydrogen flame acceleration, on the basis of the COM3D validation results against measured data of the hydrogen combustion tests in the ENACCEF and THAI facilities. The proposed analysis methodology accurately predicted the peak overpressure with an error range of approximately ±10%, using the Kawanabe model used for a turbulent flame speed in the COM3D. KAERI performed a hydrogen flame acceleration analysis using the multi-dimensional hydrogen analysis system for a severe accident initiated by a station blackout (SBO), under the assumption of 100% metal–water reaction in the Reactor Pressure Vessel (RPV), to evaluate an overpressure buildup in the containment of the Advanced Power Reactor 1400 MWe (APR1400). The magnitude of the overpressure buildup in the APR1400 containment might be used as a criterion to judge whether the containment integrity is maintained or not, when the hydrogen combustion occurs during a severe accident. The COM3D calculation results using the established analysis methodology showed that the calculated peak pressure in the containment was lower than the fracture pressure of the APR1400 containment. This calculation result might have resulted from a large air volume of the containment, a reduced hydrogen concentration owing to passive auto-catalytic recombiners installed in the containment during the hydrogen release from the RPV, and a lot of stem presence during the hydrogen combustion period in the containment. Therefore, we found that the current design of the APR1400 containment maintained its integrity when the flame acceleration occurred during the severe accident initiated by the SBO accident.

Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident in the APR1400 Containment Using a Multi-Dimensional Hydrogen Analysis System

Korea Atomic Energy Research Institute (KAERI) established a multi-dimensional hydrogen analysis system to evaluate a hydrogen release, distribution, and combustion in the containment of a nuclear power plant using MAAP, GASFLOW, and COM3D. KAERI developed the COM3D analysis methodology on the basis of the COM3D validation results against the experiments of ENACCEF and THAI. The proposed analysis methodology accurately predicts the peak overpressure with an error range of approximately ±10% using the Kawanabe turbulent flame speed model. KAERI performed a hydrogen flame acceleration analysis using the multi-dimensional hydrogen analysis system for a severe accident initiated by a station blackout (SBO) under the assumption of 100% metal-water reaction in the reactor pressure vessel for evaluating an overpressure buildup in the Advanced Power Reactor 1400 MWe (APR1400). The COM3D calculation results using the established analysis methodology showed that the calculated peak pressure in the containment was much lower than the fracture pressure of the APR1400 containment. This calculation result may have resulted from a large air volume of the containment, a reduced hydrogen concentration owing to passive auto-catalytic recombiners installed in the containment, and a lot of stem presence during the hydrogen flame acceleration in the containment. Therefore, we can know that the current design of the APR1400 containment maintains its integrity when the flame acceleration occurs during the severe accident initiated by the SBO accident.

A General Techno-Economic Model for Evaluating Emerging Electrolytic Processes

<p>Increasing societal concern about carbon emissions and the concomitant emergence of inexpensive renewable resources provide growing impetus for the electrification of the chemical industry. While there have been notable recent advances in the science and engineering of electrolytic processes, there are comparatively few engineering economic studies that outline the technical specifications needed to approach feasibility. Here we introduce an open-source techno-economic framework to connect system performance and price goals to the constituent materials property sets with a goal of quantifying the economic potential of existing and conceptual electrolytic processes. To validate the outputs and demonstrate the versatility of this toolkit, we explore three contemporary electrolyses of varying technology readiness levels. Specifically, we first benchmark our model results against the Department of Energy hydrogen analysis model, then evaluate the impact of mass transport and catalyst performance on the electrochemical reduction of carbon dioxide, and chart a pathway to low-cost electrolytic production of phenol from guaiacol. As this model is based on generalized mass balances and electrochemical equations common to a number of electrochemical processes, it serves as an adaptable toolkit for researchers to evaluate new chemistries and reactor configurations as well as to back-translate system targets to interdependent materials-level property requirements.<br></p>

A General Techno-Economic Model for Evaluating Emerging Electrolytic Processes

<p>Increasing societal concern about carbon emissions and the concomitant emergence of inexpensive renewable resources provide growing impetus for the electrification of the chemical industry. While there have been notable recent advances in the science and engineering of electrolytic processes, there are comparatively few engineering economic studies that outline the technical specifications needed to approach feasibility. Here we introduce an open-source techno-economic framework to connect system performance and price goals to the constituent materials property sets with a goal of quantifying the economic potential of existing and conceptual electrolytic processes. To validate the outputs and demonstrate the versatility of this toolkit, we explore three contemporary electrolyses of varying technology readiness levels. Specifically, we first benchmark our model results against the Department of Energy hydrogen analysis model, then evaluate the impact of mass transport and catalyst performance on the electrochemical reduction of carbon dioxide, and chart a pathway to low-cost electrolytic production of phenol from guaiacol. As this model is based on generalized mass balances and electrochemical equations common to a number of electrochemical processes, it serves as an adaptable toolkit for researchers to evaluate new chemistries and reactor configurations as well as to back-translate system targets to interdependent materials-level property requirements.<br></p>

A General Techno-Economic Model for Evaluating Emerging Electrolytic Processes

<p>Increasing societal concern about carbon emissions and the concomitant emergence of inexpensive renewable resources provide growing impetus for the electrification of the chemical industry. While there have been notable recent advances in the science and engineering of electrolytic processes, there are comparatively few engineering economic studies that outline the technical specifications needed to approach feasibility. Here we introduce an open-source techno-economic framework to connect system performance and price goals to the constituent materials property sets with a goal of quantifying the economic potential of existing and conceptual electrolytic processes. To validate the outputs and demonstrate the versatility of this toolkit, we explore three contemporary electrolyses of varying technology readiness levels. Specifically, we first benchmark our model results against the Department of Energy hydrogen analysis model, then evaluate the impact of mass transport and catalyst performance on the electrochemical reduction of carbon dioxide, and chart a pathway to low-cost electrolytic production of phenol from guaiacol. As this model is based on generalized mass balances and electrochemical equations common to a number of electrochemical processes, it serves as an adaptable toolkit for researchers to evaluate new chemistries and reactor configurations as well as to back-translate system targets to interdependent materials-level property requirements.<br></p>