Strain Rate Calculation Approach in Environmental Fatigue Evaluations

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Mark A. Gray ◽  
Matthew C. Salac ◽  
David H. Roarty ◽  
E. Lyles Cranford
Keyword(s):  
Strain Rate ◽  
Water Environment ◽  
Reactor Water ◽  
Regulatory Documents ◽  
Penalty Factor ◽  
Starting Point ◽  
Asme Code ◽  
Rate Calculation ◽  
License Renewal ◽  
Insight Into

Fatigue usage factor evaluations including the effects of reactor water environment have been performed in numerous nuclear plant license renewal efforts. A large number of these evaluations have used the environmental fatigue penalty factor, Fen, approach prescribed in various regulatory documents. The Fen equations require input of strain rate, but the prescribing documents do not provide methodology or criteria for the quantification of the strain rate to be input. As a result, numerous approaches have been offered and studied. This paper presents an approach used by Westinghouse to include strain rate in an automated calculation of Fen based on the modified rate approach (MRA) to integrated strain rate applications. The starting point of the approach is ASME Code Section III NB-3200 fatigue analysis. With environmental fatigue evaluations in new plant designs now emerging in ASME Code criteria, strain rate considerations remain part of the discussion. The intent of this paper is to provide further insight into this process.

Strain Rate Calculation Approach in Environmental Fatigue Evaluations

2010 ◽  
Author(s):  
Mark A. Gray ◽  
Matthew C. Salac ◽  
David H. Roarty ◽  
E. Lyles Cranford
Keyword(s):  
Strain Rate ◽  
Water Environment ◽  
Reactor Water ◽  
Regulatory Documents ◽  
Penalty Factor ◽  
Starting Point ◽  
Asme Code ◽  
Rate Calculation ◽  
License Renewal ◽  
Insight Into

Fatigue usage factor evaluations including the effects of reactor water environment have been performed in numerous nuclear plant license renewal efforts. A large number of these evaluations have used the environmental fatigue penalty factor, Fen, approach prescribed in various regulatory documents. The Fen equations require input of strain rate, but the prescribing documents do not provide methodology or criteria for the quantification of the strain rate to be input. As a result, numerous approaches have been offered and studied. This paper presents an approach used by Westinghouse to include strain rate in an automated calculation of Fen based on the modified rate approach to integrated strain rate applications. The starting point of the approach is ASME Code Section III NB-3200 fatigue analysis. With environmental fatigue evaluations in new plant designs now emerging in ASME Code criteria, strain rate considerations remain part of the discussion. The intent of this paper is to provide further insight into this process.

Application of Environmental Fatigue Penalty Factors and Implications for Design Analyses

2006 ◽  
Author(s):  
Mark A. Gray ◽  
E. Lyles Cranford ◽  
Paul R. Donavin
Keyword(s):  
Water Environment ◽  
Future Design ◽  
Transient Strain ◽  
Fatigue Design ◽  
Penalty Factor ◽  
Asme Code ◽  
Design Requirements ◽  
Definition Of ◽  
License Renewal ◽  
Design Analyses

A number of technical challenges have been identified in applying current methods to evaluate the effects of reactor water environment in fatigue evaluations of reactor components in license renewal applications. One challenge in using more conservative approaches is the large environmental penalty factor that may be calculated for stainless steels. The use of more sophisticated methods leads to more complex challenges, like the determination and application of transient strain rates required by the current proposed equations. For example, the definition of transients for component evaluations must consider competing effects of strain rate and stress range to assure a conservative design. As discussions extend to the possibility of addressing environmental effects in fatigue design requirements of the ASME Code, it is important to consider the implications of the challenges met in application of the current methods. This paper describes a plant-specific application of environmental fatigue penalty factors, the aspects of the challenges encountered in the application, and the ramifications of the various considerations on incorporation of fatigue environmental evaluations in future design requirements.

Application of Environmentally Assisted Fatigue Transient Ramp Times Optimization in Design Evaluations and Fatigue Monitoring Algorithms

2020 ◽  
Author(s):  
Eric Matthews ◽  
Mark Gray
Keyword(s):  
Stress Response ◽  
Parametric Study ◽  
Water Environment ◽  
Fatigue Curve ◽  
Reactor Water ◽  
Downstream Effects ◽  
Penalty Factor ◽  
Study Results ◽  
License Renewal ◽  
Response Modeling

Abstract As part of the effort for a nuclear plant to undergo license renewal, the effect of reactor water environment on fatigue life must be addressed for limiting component locations. One method to incorporate the effects of reactor water environment into the fatigue evaluations of metal components is to apply an environmental fatigue penalty factor (Fen) to the partial usage factor obtained from the design fatigue curve for each stress cycle. Fatigue evaluations have historically been performed by assuming that temperature transient loads occur at conservatively high rates to maximize the stress response and corresponding fatigue usage values. However, with consideration of reactor water environmental effects on fatigue, transients with slower rates generally produce higher Fen values that could potentially result in higher environmental fatigue usage values than transients with identical temperature changes but faster rates. A generic parametric study was performed in MRP-218 to characterize limiting transient ramp rates with respect to environmental fatigue usage for a range of piping geometry and material configurations. This paper describes the application of the parametric study results to optimize thermal hydraulic and stress response modeling assumptions with respect to transient rates and downstream effects on environmental fatigue results in both design and monitoring fatigue evaluations.

Consideration of Environmental Fatigue in the ASME Code for Carbon and Low-Alloy Steel Components

2003 ◽  
Author(s):  
Stan T. Rosinski ◽  
Arthur F. Deardorff ◽  
Robert E. Nickell
Keyword(s):  
Fatigue Life ◽  
Alloy Steel ◽  
Water Environment ◽  
Operating Experience ◽  
Nuclear Industry ◽  
Operating Conditions ◽  
Low Alloy Steel ◽  
Reactor Water ◽  
Asme Code ◽  
The Impact

The potential impact of reactor water environment on reducing the fatigue life of light water reactor (LWR) piping components has been an area of extensive research. While available data suggest a reduction in fatigue life when laboratory samples are tested under simulated reactor water environments, reconciliation of this data with plant operating experience, plant-specific operating conditions, and established ASME Code design processes is necessary before a conclusion can be reached regarding the need for explicit consideration of reactor water environment in component integrity evaluations. U.S. nuclear industry efforts to better understand this issue and ascertain the impact, if any, on existing ASME Code guidance have been performed through the EPRI Materials Reliability Program (MRP). Based on the MRP activities completed to date there is no need for explicit incorporation of reactor water environmental effects for carbon and low-alloy steel components in the ASME Code. This paper summarizes ongoing MRP activities and presents the technical arguments for resolution of the environmental fatigue issue for carbon and low-alloy steel locations.

Status Report on ASME Section III Subgroup on Design Plan for Code Changes to Implement Environmental Fatigue Evaluation Methods

2010 ◽  
Author(s):  
Jack R. Cole ◽  
John C. Minichiello
Keyword(s):  
Action Plan ◽  
Water Environment ◽  
Nuclear Industry ◽  
Status Report ◽  
Reactor Water ◽  
Class 1 ◽  
Asme Code ◽  
Code Changes ◽  
Fatigue Evaluation ◽  
The Impact

This paper provides a status report on the ASME Section III Subgroup on Design Environmental Fatigue Action Plan. The plan will direct development of ASME Section III Code [1] changes to provide guidance on acceptable methods for evaluating reactor water environment effects on reactor coolant pressure boundary components. Section III provides indication to the user that special consideration should be given for the environment to which a component is exposed, but does not provide guidance in addressing these effects. Discussions on needed ASME Code changes to address reactor water environmental effects have been under consideration by ASME Code bodies for many years. Due to the renaissance of the nuclear industry it is now apparent that Section III should be up-dated to address the missing guidance. The action plan was developed by the Subgroup on Design to coordinate activities necessary for Code bodies to act on proposed Code changes that will provide the user with the necessary tools to evaluate the effect of reactor water environment on fatigue life of components. The action plan lays out a strategy for a staged implementation of analysis methodologies, needed research, analysis guides, sample problems, and an assessment of the impact of the new rules upon the industry. The ultimate goal of the Subgroup on Design is to develop a new non-mandatory appendix that provides guidance to the user when evaluating reactor water environmental fatigue effects on Class 1 components.

A Parametric Study Into the Competing Effects of Stress and Strain Rate in Environmental Fatigue Usage Calculations

2013 ◽  
Author(s):  
Julian Emslie ◽  
Chris Watson
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Detrimental Effect ◽  
Stress And Strain ◽  
Plant Materials ◽  
Penalty Factor ◽  
Asme Code ◽  
Parametric Studies ◽  
Thermal Transient ◽  
Stress And Strain Rate

Data have emerged that indicate a Pressurised Water Reactor (PWR) environment can have a significant detrimental effect on the fatigue life of plant materials. Proposed methods for accounting for the PWR environment in an ASME III fatigue assessment are presented in ASME Code Case N-792 and NUREG/CR-6909, both of which use a fatigue penalty factor (Fen) approach that directly multiplies the Partial Usage Factor (PUF). Formulae are provided for the Fen factor which are dependent on strain rate, temperature and the dissolved oxygen content of the water. A slower strain rate provides for increased Fen values and therefore increased PUFs. In stress analysis, defining the ramp of a thermal transient as a step change is pessimistic for thermal stress calculations. The dependence of the Fen factor on strain rate means that this approach may not be conservative when the stresses are carried through to a PWR environment enhanced ASME III fatigue calculation. An increased ramp time gives a lower stress, however this also provides for a slower strain rate, and therefore a larger Fen factor. By a series of parametric studies using simple austenitic stainless steel 2D axisymmetric cylinder FE models, this paper examines the competing effects of reduced stress and increased Fen that an increased transient ramp time has upon a PWR environment enhanced ASME III calculated fatigue usage factor for stainless steel components. It was found for thin walled sections that the assumption of a step to define the thermal transient is still pessimistic despite the competing effects. For thicker sections the results showed that this is not always the case, but the potential increase in PUF was found to be minimal.

The Word Class Adjective in English Business Magazines Online

2018 ◽  
Vol 6 (2) ◽  
pp. 99-115
Author(s):  
Borislav Marušić ◽  
Sanda Katavić-Čaušić
Keyword(s):  
Empirical Study ◽  
Empirical Analysis ◽  
Word Formation ◽  
Word Class ◽  
Business English ◽  
Starting Point ◽  
Comprehensive Picture ◽  
English Syntax ◽  
The Empirical Analysis ◽  
Insight Into

Abstract The aim of this paper is to research the word class adjective in one sequence of the ESP: Business English, more precisely English business magazines online. It is an empirical study on the corpus taken from a variety of business magazines online. The empirical analysis allows a comprehensive insight into the word class adjective in this variety of Business English and makes its contribution to English syntax, semantics and word formation. The syntactic part analyses the adjective position in the sentence. The semantic part of the study identifies the most common adjectives that appear in English business magazines online. Most of the analysis is devoted to the word formation of the adjectives found in the corpus. The corpus is analysed in such a way that it enables its division into compounds, derivatives and conversions. The results obtained in this way will give a comprehensive picture of the word class adjective in this type of Business English and can act as a starting point for further research of the word class adjective.

Strain Rate Evaluation of Some Typical Nuclear Power Plant Components During Plant Operation

2010 ◽  
Author(s):  
Koji Dozaki ◽  
Hiromasa Chitose ◽  
Hiroshi Ogawa ◽  
Hideo Machida
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Strain History ◽  
Strain Rates ◽  
Peak Strain ◽  
Plant Operation ◽  
Thermal Transients ◽  
Reactor Water ◽  
Rate Evaluation ◽  
Reactor Internals

The dynamic aspects of loading conditions for reactor internals, piping and the like, are thought to play important roles in the initiation of failures due, for example, to stress corrosion cracking (SCC) and fatigue. Some reports show that a strain rate on the order of 10−7 s−1 most affects susceptibility to SCC in the BWR reactor water environment. Environmental fatigue, which exhibits a shorter fatigue life in reactor water than that in air, is considered to have a remarkable correlation with strain rate and its affect on fatigue life. Despite its significant affect on SCC and fatigue, the actual strain rate of components is not known and practical evaluation methods have not been developed; consequently, such failure modes as SCC and fatigue are not evaluated in design. For this paper, strain rates induced by dynamic loading during such operations as plant start-up were calculated at typical points, such as reactor internals, piping and so on. The finite element method was applied to calculate the strain history of each point, and the strain rate was evaluated. The strain rate evaluation results clearly demonstrated that thermal transients provide greater peak strain rate values than pressure transients. Strain rates on the order of 10−7 s−1 were obtained for most points of major components during such thermal transients as plant start-ups. The major factors determining the strain rate magnitude were discussed, based on the calculation results. It was shown that the rate of temperature rise was the most important parameter, because it exhibited much larger sensitivity than the other parameters on the strain rate and could be controlled by plant operation procedures. In addition, a simple strain rate evaluation method based on Green’s function was developed for a specific point with a given design condition.

Accuracy of heart strain rate calculation derived from Doppler tissue velocity data

2001 ◽  
Author(s):  
Andres Santos ◽  
Maria J. Ledesma-Carbayo ◽  
Norberto Malpica ◽  
Manuel Desco ◽  
Jose C. Antoranz ◽  
...  
Keyword(s):  
Strain Rate ◽  
Velocity Data ◽  
Tissue Velocity ◽  
Rate Calculation

Designing the Person: Sociological Assumptions Embodied within the Architecture of Charles Rennie Mackintosh and Le Corbusier

2005 ◽  
Vol 14 (1) ◽  
pp. 141-162
Author(s):  
Clare Spencer
Keyword(s):  
Social Interaction ◽  
Comparative Study ◽  
Le Corbusier ◽  
Western Society ◽  
Architectural Practice ◽  
Individual Person ◽  
Interesting Insight ◽  
Starting Point ◽  
The Individual ◽  
Insight Into

This essay presents a comparative study of the sociological assumptions implicit, and to some extent explicit, in the work of two famous architects, Charles Rennie Mackintosh and Le Corbusier. The inhabitant implied through the architectural practice of Le Corbusier resembles Elias's homo clausus (closed person), the mode of self experience viewed by Elias as the dominant one in Western society and one which sees the individual person as a ‘thinking subject’ and the starting point of knowledge. Mackintosh's designs, in contrast, imply individual people closer to Elias‘s homines aperti, social beings who are shaped through social interaction and interdependence. This paper demonstrates how, as well as fulfilling social, cultural and political needs, architecture carries, within in its designs, certain assumptions about how people and how they do, and should, live. The adoption of an Eliasian perspective provides an interesting insight into how these assumptions can shape self-experience and social interaction in the buildings of each architect.

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