Long-term geotextile degradation mechanisms and exposed lifetime predictions

Geotextiles ◽  
2016 ◽  
pp. 217-236
Author(s):  
R.M. Koerner
Keyword(s):  
Degradation Mechanisms

Influence of Overgrown Micropipes in the Active Area of SiC Schottky Diodes on Long Term Reliability

2005 ◽  
Vol 483-485 ◽  
pp. 925-928 ◽  
Author(s):  
Roland Rupp ◽  
Michael Treu ◽  
Peter Türkes ◽  
H. Beermann ◽  
Thomas Scherg ◽  
...  
Keyword(s):  
Leakage Current ◽  
Power Dissipation ◽  
Schottky Diodes ◽  
Physical Structure ◽  
Active Area ◽  
Clear Correlation ◽  
Local Power ◽  
Degradation Mechanisms ◽  
Failure Simulation

Other than open micropipes (MP), overgrown micropipes do not necessarily lead to a^significantly reduced blocking capability of the affected SiC device. However they can lead to a degradation of the device during operation. In this paper the physical structure of overgrown micropipes will be revealed and their contribution to the leakage current will be shown. The possible impact of the high local power dissipation in the surrounding of the overgrown micropipe will be discussed and long term degradation mechanisms will be described. Failure simulation under laboratory conditions shows a clear correlation between the position of overgrown micropipes and the location of destructive burnt spots.

Degradation Susceptibility Metrics as the Bases for Bayesian Reliability Models of Aging Passive Components and Long-Term Reactor Risk

2011 ◽  
Author(s):  
Stephen D. Unwin ◽  
Peter P. Lowry ◽  
Michael Y. Toyooka ◽  
Benjamin E. Ford
Keyword(s):  
Passive Component ◽  
Degradation Mechanisms ◽  
Component Reliability ◽  
Passive Components ◽  
Reliability Models ◽  
Age Dependent ◽  
Probabilistic Risk Assessments ◽  
Component Failure Rates ◽  
Service Data

Conventional probabilistic risk assessments (PRAs) are not well-suited to addressing long-term reactor operations. Since passive structures, systems and components are among those for which refurbishment or replacement can be least practical, they might be expected to contribute increasingly to risk in an aging plant. Yet, passives receive limited treatment in PRAs. Furthermore, PRAs produce only snapshots of risk based on the assumption of time-independent component failure rates. This assumption is unlikely to be valid in aging systems. The treatment of aging passive components in PRA does present challenges. First, service data required to quantify component reliability models are sparse, and this problem is exacerbated by the greater data demands of age-dependent reliability models. A compounding factor is that there can be numerous potential degradation mechanisms associated with the materials, design, and operating environment of a given component. This deepens the data problem since the risk-informed management of materials degradation and component aging will demand an understanding of the long-term risk significance of individual degradation mechanisms. In this paper we describe a Bayesian methodology that integrates the metrics of materials degradation susceptibility being developed under the Nuclear Regulatory Commission’s Proactive Materials Degradation Assessment Program with available plant service data to estimate age-dependent passive component reliabilities. Integration of these models into conventional PRA will provide a basis for materials degradation management informed by the predicted long-term operational risk.

Long-Term Operation of BWR RPV and its Internals

2018 ◽  
Author(s):  
Otso Cronvall
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Pilot Project ◽  
Computational Time ◽  
Degradation Mechanisms ◽  
Irradiation Embrittlement ◽  
Screening Process ◽  
Term Operation ◽  
Operational Lifetime

This study concerns the long-term operation (LTO) of a boiling water reactor (BWR) reactor pressure vessel (RPV) and its internals. The main parts of this study are: survey on susceptibility to degradation mechanisms, and computational time limited ageing analyses (TLAAs). The ageing of nuclear power plants (NPPs) emphasises the need to anticipate the possible degradation mechanisms. The BWR survey on susceptibility to these uses the OL1/OL2 RPVs and significant internals as a pilot project. It is not necessary to carry out the TLAAs for all components. Some components were excluded from the TLAAs with a screening process. To do this, it was necessary to determine the component specific load induced stresses, strains and temperature distributions as well as cumulative usage factor (CUF) values. For the screened-in components, the TLAAs covered all significant time dependent degradation mechanisms. These include (but are not limited to): • irradiation embrittlement, • fatigue, • stress corrosion cracking (SCC), and • irradiation accelerated SCC (IASCC). For the components that were screened-in, the potential to brittle, ductile or other degradation was determined. Only some of the most significant cases and results are presented. According to the analysis results, the operational lifetime of the OL1/OL2 RPVs and internals can safely be extended from 40 to 60 years.

Evaluation of PBTS and NBTS in SiC MOS Using In Situ Charge Pumping Measurements

2013 ◽  
Vol 740-742 ◽  
pp. 545-548 ◽  
Author(s):  
Daniel B. Habersat ◽  
Aivars J. Lelis ◽  
Ronald Green ◽  
Mooro El
Keyword(s):  
Charge Trapping ◽  
Operating Conditions ◽  
Degradation Mechanisms ◽  
Power Devices ◽  
Charge Pumping ◽  
Long Term Stability ◽  
Accelerated Degradation ◽  
Mos Devices

Since power devices such as DMOSFETs will operate at higher temperatures with accelerated degradation mechanisms, it is essential to understand the effects of typical operating conditions for power electronics applications. We have found that SiC MOSFETs when gate-biased at 150 °C show an increasing charge pumping current over time, suggesting that interface traps (or perhaps near-interface oxide traps) are being created under these conditions. This trapping increase occurs slightly above linear-with-log-time and mimics previously observed threshold voltage instabilities, though a causal relationship has not yet been determined. We found the charge trapping after 104 s of BTS increased at a rate of 1x1011 cm-2/dec for NBTS (-3 MV/cm), 0.7x1011 cm-2/dec for PBTS (3 MV/cm), and 0.3x1011 cm-2/dec when grounded. The observed increase in charge trapping has negative implications for the long term stability and reliability of SiC MOS devices under operating conditions.

scholarly journals Model for Staebler-Wronski Degradation Deduced from Long-Term, Controlled Light-Soaking Experiments

2000 ◽  
Vol 609 ◽  
Author(s):  
Bolko von Roedern ◽  
Joseph A. del Cueto
Keyword(s):  
Light Intensity ◽  
Amorphous Silicon ◽  
Operating Conditions ◽  
Degradation Mechanisms ◽  
Time Constants ◽  
Photovoltaic Modules ◽  
History Of ◽  
Exposure History ◽  
Operating History

ABSTRACTLong-term light-soaking experiments of amorphous silicon photovoltaic modules have now established that stabilization of the degradation occurs at levels that depend significantly on the operating conditions, as well as on the operating history of the modules. We suggest that stabilization occurs because of the introduction of degradation mechanisms with different time constants and annealing activation energies, depending on the exposure conditions. Stabilization will occur once a sufficient accumulation of different degradation mechanisms occurs. We find that operating module temperature during light-soaking is the most important parameter for determining stabilized performance. Next in importance is the exposure history of the device. The precise value of the light intensity seems least important in determining the stabilized efficiency, as long as its level is a significant fraction of 1-sun.

scholarly journals Resistance of a Silicone Membrane to Long-term UV and Moisture Aging in Light of Climate Change

2021 ◽  
Author(s):  
Jean-François Masson ◽  
Peter Collins ◽  
Marzieh Riahinezhad ◽  
Itzel Lopez-Carreon ◽  
Jocelyn Johansen
Keyword(s):  
Climate Change ◽  
Material Characterization ◽  
Room Temperature ◽  
Accelerated Aging ◽  
Building Envelope ◽  
Degradation Mechanisms ◽  
Aging Conditions ◽  
And Storage ◽  
Silicone Membranes

Three room-temperature fluid-applied silicone membranes intended for application in the building envelope were studied in this work. The membranes were subjected to 5000 hours of accelerated UV and moisture aging to evaluate their resistance to long-term aging. The properties of the membranes were studied to understand any degradation mechanisms that might happen during accelerated aging. The weight loss, wetting propensity, cracking and oxidation resistance, and storage modulus were measured at different intervals during the 5000 hours of aging. Based on the material characterization results, the silicone membranes proved to be resilient under aggressive accelerated UV radiation and moisture aging, conditions which can be expected as a result of climate change.

Building the Technical Case for Long-Term Operation

2015 ◽  
Author(s):  
Richard Tilley ◽  
Robin Dyle
Keyword(s):  
Operating Experience ◽  
Academic Community ◽  
Degradation Mechanisms ◽  
Comprehensive Understanding ◽  
Term Operation ◽  
Societal Benefits ◽  
Actual Operating ◽  
Nuclear Plants ◽  
The Us

United States (US) and International utilities are actively engaged in assessing the economic and societal benefits of operating nuclear plants beyond their initial license periods. Nuclear plant generated electricity is still the largest contributor to non-carbon dioxide emitting generation. In the US, a majority of operating plants has already received approval for an additional 20 years of operation, and soon it is expected that utilities will begin the process to seek a second 20 year renewal. The keys to successful renewal are to maintain safe and reliable operations by building a sound technical case through the following activities: • Develop comprehensive understanding of aging degradation issues for systems, structures and components (SSCs) • Implement specific plant aging management programs to address aging degradation • Confirm behavior of degradation mechanisms for the entire period of operation This paper will step through the above elements to illustrate how a strong technical case may be created for safe and reliable long-term operation. Examples or case studies will be provided to clearly link the fundamental science of materials degradation to the inspection, testing and evaluation efforts implemented at a plant and to the confirmatory data that is provided by both actual operating experience and the extensive research and development projects pursued by industry, governments, and the academic community.

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