Session: 06-02 Nuclear Codes, Standards, Licensing, & Regulatory Issues Session 2

Paper Number: 135159

135159 - Inelastic Analysis and Evaluation Method of High-Temperature Components Based on the Material Data of Incoloy 800h in Asme Iii-5 

Abstract: 

High temperature gas cooled reactor (HTGR), as a next generation nuclear reactor, capable of operating at temperatures over 550°C with advantages such as high efficiency and flexibility, holds promising prospects. The steam generator (SG) plays a crucial role in energy exchange between primary and secondary circuits. The components of SG operating at elevated temperature are mainly made of Incoloy 800H, which is one of the five materials recommended in the ASME Code Section III Division 5 for constructing High temperature components. However, they bear the risk of failure due to time-dependent creep damage and time-independent fatigue damage during transient service conditions at operating temperature, which challenges the designers in design and analysis activities. ASME III-5 provides design methods for high temperature components based on finite element analysis, including elastic analysis (or simplified inelastic analysis) and inelastic analysis. The Code provides the specific practical guidelines for applying elastic analysis. However, the Code does not specify the detailed and comprehensive material inelastic constitutive model for inelastic analysis, so the designer needs to choose a suitable constitutive model by himself, which makes it impossible for the designer to complete the inelastic analysis and design of high temperature components directly according to the existing specification. In this paper, the inelastic constitutive model was reconstructed according to the isochronous stress strain curve of Incoloy 800H provided by ASME III-5, and the elastoplastic and creep constitutive models were verified. According to the requirements for inelastic analysis in ASME III-5 high temperature components, the effect of plastic strain hardening including cyclic loading effect and hardening with high temperature exposure and the effect of creep strain hardening needs to be considered, therefore some hypothesis for cyclic hardening are established for the implementation of the methodology only by the material data provided by the Code. Then the calculation program was developed using the numerical programming tool of ABAQUS subroutine, and the data of the expected minimum stress-to-rupture values and the design fatigue strain range were combined. The strain limit evaluation and creep fatigue damage evaluation of high-temperature components are realized based on inelastic analysis. A simple example is presented to demonstrate the process of using inelastic analysis method and elastic analysis method. Finally, the evaluation results of two methodologies are compared, and the application scenarios and advantages of inelastic analysis method are further demonstrated. Further considerations on the applications of inelastic analysis under complex service conditions are also discussed.

Presenting Author: Sixuan He Tsinghua University

Presenting Author Biography: Sixuan He received the B.E. degree in Engineering Mechanics from Tianjin University, Tianjin, China, in 2011 and the M.Sc. degree in Computational Mechanics from Technical University of Munich, Munich, Germany, in 2015. He is currently working toward the Ph.D. degree in Nuclear Science and Technology with the Institute of Nuclear and New Energy Technology , Tsinghua University, Beijing, China. His research interests include High temperature Experiment method, Inelastic Analysis and Integrity evaluation of High temperature components.

Authors:

Sixuan He Tsinghua University
Heng Peng Tsinghua University
Li Shi Tsinghua University
Xinxin Wu Tsinghua University