Environmental Fatigue Evaluation for Primary Components of APR1400 Reactor Coolant System

2010 ◽  
Author(s):  
J. M. Kim ◽  
K. W. Kim ◽  
K. S. Yoon ◽  
S. H. Park ◽  
I. Y. Kim ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Integral Method ◽  
Power Reactor ◽  
Light Water Reactor ◽  
Outlet Nozzle ◽  
Design Life ◽  
Class 1 ◽  
Asme Code ◽  
Fatigue Evaluation ◽  
Coolant System

USNRC Regulatory Guide (RG) 1.207 provides a guideline for evaluating fatigue analyses due to the environmental effects on the new light water reactor (LWR). The environmental correction factor (Fen) is used to incorporate the LWR environmental effect into fatigue analyses of ASME Class 1 components. In this paper, the environmental fatigue evaluation is applied to some primary components with 60 year design life of Advanced Power Reactor (APR1400). The materials sampled from Class 1 components are the low alloy steel for the reactor vessel (RV) outlet nozzle and the carbon steel for the hot leg which are attached to the outlet nozzle. The simplified method, time-based integral method and strain-based integral method are used to compute the Fen values. The calculated fatigue usage factors including the environmental effects are compared with those obtained using the current ASME Code rules. As the calculated cumulative fatigue usage factor considering environmental effects (CUFen) is below 1.0, there is no concern for the RV outlet nozzle to implement design for environmental fatigue effects.

Fatigue Evaluation for Section III, Class 1 Components Using Flaw Tolerance Method to Consider Environmental Effects

2015 ◽  
Author(s):  
David Roarty ◽  
Wolf Reinhardt ◽  
David Dewees
Keyword(s):  
Fatigue Crack ◽  
Environmental Effects ◽  
Design Assessment ◽  
Flaw Tolerance ◽  
Design Life ◽  
Tolerance Approach ◽  
Class 1 ◽  
Fatigue Evaluation ◽  
Tolerance Method ◽  
Type 304

An ASME Section III Task Group (TG) was formed in 2012 to develop alternate rules for the design assessment of Section III Class 1 nuclear components subject to fatigue service with environmental effects. A Section III Code Case has been proposed with the purpose of providing a method for performing fatigue evaluations of Class 1 components when the effects of a light water reactor environment on fatigue life are judged to be significant and cumulative usage factor (CUF) limits may not be satisfied. The Code Case implements a flaw tolerance approach by postulating that a fatigue crack initiates at the beginning of life and is subjected to fatigue crack growth under the specified design cycles. It must be demonstrated that the crack would remain stable with set margin throughout the design life of the component or part under consideration, and would remain confined to an acceptable fraction of the wall thickness. At this time, the application is limited to type 304/304L and 316/316L austenitic steel. This paper discusses the methodology and technical background of the proposed Code Case.

Application of Draft Regulatory Guide DG-1144 Guidelines for Environmental Fatigue Evaluation to a BWR Feedwater Piping System

2007 ◽  
Author(s):  
Hardayal S. Mehta ◽  
Henry H. Hwang
Keyword(s):  
Fatigue Life ◽  
Thermal Cycle ◽  
Light Water Reactor ◽  
Piping System ◽  
Low Alloy Steel ◽  
Light Water ◽  
Asme Code ◽  
Fatigue Evaluation ◽  
Cycle Diagram ◽  
Analytical Expressions

Recently published Draft Regulatory Guide DG-1144 by the NRC provides guidance for use in determining the acceptable fatigue life of ASME pressure boundary components, with consideration of the light water reactor (LWR) environment. The analytical expressions and further details are provided in NUREG/CR-6909. In this paper, the environmental fatigue rules are applied to a BWR feedwater line. The piping material is carbon steel (SA333, Gr. 6) and the feedwater nozzle material is low alloy steel (SA508 Class 2). The transients used in the evaluation are based on the thermal cycle diagram of the piping. The calculated fatigue usage factors including the environmental effects are compared with those obtained using the current ASME Code rules. In both cases the cumulative fatigue usage factors are shown to be less than 1.0.

Study of the Effects of Environment in the Fatigue Analysis on Existing LWR as Proposed in USNRC RG 1.207

2009 ◽  
Author(s):  
Eugene Tom ◽  
Milton Dong ◽  
Hong Ming Lee
Keyword(s):  
Fatigue Life ◽  
Correction Factor ◽  
Environmental Effects ◽  
Environmental Parameters ◽  
Computer Code ◽  
Cyclic Behavior ◽  
Simplified Approach ◽  
Asme Code ◽  
Detailed Computer ◽  
Fatigue Evaluation

US NRC Regulatory Guide 1.207 Rev. 0 provides guidance for use in determining the acceptable fatigue life of ASME pressure boundary components, with consideration of the light-water reactor (LWR) environment. Because of significant conservatism in quantifying other plant-related variables (such as cyclic behavior, including stress and loading rates) involved in cumulative fatigue life calculations, the design of the current fleet of reactors is satisfactory. For new plants under design and current operating plants considering applying for License Renewal, the environment effects may need to be considered in the design. RG 1.207 proposes using an environmental correction factor (Fen) to account for LWR environments by correcting the fatigue usage calculated with the ASME “air” curves. The Fen method is presented in NUREG/CR-6909, “Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials”. By definition, Fen is the ratio of fatigue life of the component material at room temperature air environments to its fatigue life in LWR coolant at operating temperature. To incorporate environmental effects into the fatigue evaluation, the fatigue usage is calculated using provisions set forth in Section III of the ASME Code, and is adjusted by multiplying a correction factor. The calculated Fen values are then used to incorporate environmental effects into ASME fatigue usage factor evaluation. Once the environmental correction factors have been determined, the previously calculated allowable number of cycles for each load set pair based on the current Code fatigue design curve can be adjusted to determine the new fatigue usage factors for environmental effects. This paper presents a study of the effect of the Regulatory Guide if it is to be implemented on the current fleet of LWR. A quick assessment of the sensitivity of the various environmental parameters is also included in this paper. The comparison of environmental effects between the simplified approach in this paper and the results with detailed computer analyses, such as Unisont’s propriety computer code UPIPENB (Ref. 4), will be our next research project to be presented in the future conference.

Environmental Fatigue Evaluation of a Korean Nuclear Power Plant

2008 ◽  
Author(s):  
Chang-Kyun Oh ◽  
Hyun-Su Kim ◽  
Hag-Ki Youm ◽  
Tae-Eun Jin ◽  
Young-Jin Kim
Keyword(s):  
Fatigue Life ◽  
Pressure Vessel ◽  
Nuclear Power ◽  
Reactor Pressure Vessel ◽  
Moment Stress ◽  
Wide Range ◽  
Class 1 ◽  
Asme Code ◽  
Fatigue Evaluation ◽  
Reactor Pressure

In accordance with the recommendation of USNRC and the U.S. license renewal experiences, the effects of reactor coolant environment on the fatigue life have to be considered for the continued operation of operating nuclear power plants as well as for the design of new plants. Although various evaluation methodologies have been suggested to date, a wide range of comparison of the existing methodologies has not been performed. The purpose of this paper is to evaluate the environmental effects on the fatigue life of a reactor pressure vessel and ASME Class 1 piping by the various methodologies and to investigate the effects of the pressure and moment stress histories on the environmental fatigue evaluation. The evaluation results show that the environmental fatigue evaluation results based on the design cumulative usage factors for the reactor pressure vessel and ASME Class 1 piping satisfy the requirement of the ASME code except for charging nozzle. However, when using operating cumulative usage factor, the environmental fatigue evaluation result for the charging nozzle satisfies the ASME code allowable. And the effects of the pressure and moment stress histories on the environmental fatigue evaluation are considered to be small when using the modified rate approach.

An Investigation on the Reduction Schemes of Environmental Fatigue Usage Factor for Pressurizer Surge Line

2011 ◽  
Author(s):  
Sun-yeh Kang ◽  
Won-ho Jo ◽  
Min-sup Song ◽  
Ki-seok Yoon ◽  
Taek-sang Choi ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Light Water Reactor ◽  
Life Extension ◽  
Regulatory Requirement ◽  
Light Water ◽  
Plant Life ◽  
Asme Code ◽  
Surge Line ◽  
Critical Components ◽  
Fatigue Evaluation

For plant life extension, it is the regulatory requirement to assess reactor coolant environmental impacts on critical components of the nuclear power plant including at least those mentioned in NUREG/CR-6260[2]. The pressurizer surge line is the most easy-to-fail component in view of LWR (Light Water Reactor) environments when it comes to meeting the current ASME code limit of the fatigue evaluation. Cumulative Usage Factor (CUF) value could be increased to a maximum of 15.35 times due to the environmental effects, which makes it easy to exceed the allowable fatigue limit (1.0). This paper discusses the process of the environmental correction factor calculation described in NUREG/CR-5704[4], and five proposed schemes for reducing the environmental CUF value to the ASME code limit or below. This paper concludes that the proposed schemes are effective in lowering the environmental CUF value of the pressurizer surge line.

ASME Section III Flaw Tolerance Sample Problem for Fatigue Design of Nuclear System Components

2014 ◽  
Author(s):  
David J. Dewees ◽  
Paul Hirschberg ◽  
Wolf Reinhardt ◽  
Gary L. Stevens ◽  
David H. Roarty ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Water Environment ◽  
Sample Problem ◽  
Design Assessment ◽  
Thermal Transients ◽  
Flaw Tolerance ◽  
Initial Task ◽  
Class 1 ◽  
Fatigue Evaluation ◽  
Technical Basis

An ASME Section III Task Group (TG) was formed in 2012 to develop alternate rules for the design assessment of Section III Class 1 nuclear components subject to fatigue service with environmental effects. Specifically, a flaw tolerance approach is being investigated based on similar methodology to that found in ASME Section XI Nonmandatory Appendix L. A key initial task of the TG (which reports to the Section III Working Group on Environmental Fatigue Evaluation Methods) was to develop and solve a detailed sample problem. The intent of the sample problem was to illustrate application of proposed rules, which will be documented as a Section III Code Case with a supporting technical basis document. Insights gained from round robin solution of the sample problem are presented and discussed in this paper. The objective of documenting the findings from the sample problem are to highlight the observed benefits and limitations of the proposed procedures, particularly how rules typically associated with in-service experience might be adapted into design methods. The sample problem is based on a heavy-walled stainless steel nozzle that meets cumulative fatigue usage requirements in air (i.e., usage factor, U, without reactor water environment effects less than unity), but fails to meet usage factor requirements when environmental fatigue effects are applied. The sample problem demonstrates that there is a class of problems dominated by severe thermal transients where fatigue initiation is predicted based on elastic methods including environmental effects, but fatigue crack propagation results are acceptable. Preliminary conclusions are drawn based on the results of the sample problem, and the next steps are also identified.

An Investigation Into the Feasibility of Environmental Fatigue Design for APR 1400 Primary Components and Piping With a 60 Year Design Life

2003 ◽  
Author(s):  
J.-S. Park ◽  
J.-M. Kim ◽  
G.-S. Kim ◽  
T.-S. Choi
Keyword(s):  
Design Methodology ◽  
Low Alloy Steel ◽  
Fatigue Design ◽  
Design Life ◽  
Division 1 ◽  
Asme Code ◽  
Alternative Approaches ◽  
Surge Line ◽  
Coolant System ◽  
Reactor Pressure

This paper investigates the feasibility of environmental fatigue design for the APR1400 with the 60 year design life, which is based on sample evaluations of fatigue lives for the component and piping designed to the ASME Code Section III, Division 1. The materials sampled from the reactor coolant system (RCS) components are the low alloy steel for reactor pressure vessel outlet nozzles and the austenitic stainless steel for pressurizer surge line piping. Environmental fatigue evaluations of the component materials are performed employing the environment factor approach. Based on the evaluation results it is concluded the environmental fatigue design of the RCS components and piping for the APR1400 is not feasible as the Code requirement, and alternative approaches need be developed removing various conservatisms in the fatigue design methodology.

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.

scholarly journals Consistent Creep and Rupture Properties for Creep-Fatigue Evaluation

1979 ◽  
Vol 101 (4) ◽  
pp. 276-285 ◽  
Author(s):  
C. C. Schultz
Keyword(s):  
Fatigue Life ◽  
Factor Of Safety ◽  
304 Stainless Steel ◽  
Code Design ◽  
Class 1 ◽  
Creep Fatigue ◽  
Asme Code ◽  
Accepted Practice ◽  
Fatigue Evaluation ◽  
Rupture Properties

The currently accepted practice of using inconsistent representations of creep and rupture behaviors in the prediction of creep-fatigue life is shown to introduce a factor of safety beyond that specified in current ASME Code design rules for 304 stainless steel Class 1 nuclear components. Accurate predictions of creep-fatigue life for uniaxial tests on a given heat of material are obtained by using creep and rupture properties for that same heat of material. The use of a consistent representation of creep and rupture properties for a minimum strength heat is also shown to provide reasonable predictions. The viability of using consistent properties (either actual or those of a minimum strength heat) to predict creep-fatigue life thus identifies significant design uses for the results of characterization tests and improved creep and rupture correlations.

Sign in / Sign up

Export Citation Format

Share Document