Values for Lennard-Jones temperatures between 200 and parameters, calculated from recently measured viscosity data for 500 K, are reported for ten small molecules.
The rate of growth of flaws in reactor circuit components by fatigue is usually determined using the reference crack growth curves in Section XI of the ASME Boiler and Pressure Vessel Code. These curves describe the rate of crack propagation per cycle (da/dN) as a function of the applied stress intensity factor range (ΔK). No reference curves for water-wetted defects in austenitic stainless steels are currently available. This paper describes the results of testing of Type 304L stainless steel in simulated PWR primary coolant over a range of temperatures and mechanical loading conditions. The data on wrought stainless steel presented in this paper demonstrate that crack growth rates can be significantly enhanced by the PWR primary environment at temperatures between 150°C and 300°C. The degree of enhancement increases significantly with reducing loading frequency and decreases with decreasing water temperature. The environmental influence on fatigue is also smaller at very high R ratio (≥0.85). At long rise times the maximum enhancement of crack growth rate over inert crack growth rates was between 1 and 2 orders of magnitude at 250–300°C. However there is evidence that at very long rise times the environmental effect starts to decrease again. The conditions under which this occurs are influenced by temperature and water flowrate, with turbulent flow conditions appearing to have a limited beneficial effect. Due to the strong time dependence of crack growth rate, the data are best rationalized using a time domain (a˙e–a˙i) approach.
INCEFA-PLUS stands for INcreasing safety in nuclear power plants by Covering gaps in Environmental Fatigue Assessment. It is a five year project supported by the European Commission HORIZON2020 program that commenced in mid-2015 and in which sixteen organizations from across Europe participate. Specifically, the effects of mean strain/stress, hold time, strain amplitude and surface finish on fatigue life of austenitic stainless steels in light water reactor environments are being studied, these being issues of common interest to all participants. The project will develop proposals for improvements to methods for environmental fatigue assessment of nuclear plant components. Therefore, extensive testing capacity is being solicited in various laboratories across Europe in order to add to the existing amount of published data on environmentally assisted fatigue. Since there currently is no standard on environmental fatigue testing, it was imperative to come up with and agree upon a testing procedure within the consortium to minimize lab-to-lab variations in test results. This was done prior to the first phase of testing, but an update of the procedure was required after review of initial results, when additional potential lab-to-lab differences were identified. The current status of the so-called test protocol, and the key areas of difference found between different testing facilities, will be discussed. Due to the large test matrix within INCEFA-PLUS, distributed amongst various test laboratories, it has been necessary to develop a method to assign a data quality level to each test result, and a minimum data quality requirement for results that will be included in the project’s datasets used for analysis. Furthermore, the project has triggered international interest in facilitating mutual data access, and this requires data is gathered in a common database with data quality ratings applied. Ways to address the evaluation of data quality will be discussed. In a way, both activities, on a test protocol and on data review, jointly contribute to data quality by, respectively, ensuring a pre-test, common test procedure and a post-test, harmonized data evaluation. The large number of participants in the INCEFA-PLUS project presents a unique opportunity to gain consensus on light water reactor environment fatigue testing procedures and data quality assessment from experts working in a range of different organizations. The test protocol and data quality ratings developed within the INCEFA-PLUS project could be adopted by other organizations, or possibly used as the basis for future testing standards documents to harmonize approaches across the nuclear industry.
INCEFA-PLUS is a major new five year project supported by the European Commission HORIZON2020 program. The project commenced in mid 2015. 16 organizations from across Europe have combined forces to deliver new experimental data which will support the development of improved guidelines for assessment of environmental fatigue damage to ensure safe operation of nuclear power plants. Prior to the start of INCEFA-PLUS, an in-kind study was undertaken by several European organizations with the aim of developing the current state of the art for this technical area. In addition to stress/strain amplitude, this study identified three additional experimental variables which required further study in order to support improved assessment methodology for environmental fatigue, namely the effects of mean stress/strain, hold time and surface finish. Within INCEFA-PLUS, the effects of these three variables on fatigue endurance of austenitic stainless steels in light water reactor environments are therefore being studied experimentally. The data obtained will be collected and standardized in an online environmental fatigue database. A dedicated CEN workshop will deliver a harmonized data format facilitating the exchange of data within the project but also beyond. Based on the data generated and the resulting improvement in understanding, it is planned that INCEFA-PLUS will develop and disseminate methods for including the new data into assessment procedures for environmental fatigue degradation. This will take better account of the effects of mean stress/strain, hold time and surface finish. This paper will describe the background to the project and will explain the expectations for it.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.