Method of adopting strain sensor to monitor fatigue of nuclear grade pipelines

Abstract

The invention discloses a method of adopting a strain sensor to monitor the fatigue of nuclear grade pipelines. At first, a strain sensor (a strain sheet or a strain meter) is used to monitor the strain of the external surface of a nuclear grade pipeline; then according to the external surface strain of the nuclear grade pipeline, the properties of the material of the nuclear grade pipeline, and information of an existed monitoring device of the nuclear power plant, the strain of the internal wall of the nuclear grade pipeline can be determined; then alternation amplitude in strain circulations and corresponding circulation times can be determined; according to a preset epsilon-N curve, the fatigue use coefficient is calculated; then according to the pipeline strain history, the reasonable environmental influence coefficient (Fen) is determined, the fatigue use coefficient is corrected; finally, the fatigue use coefficient is output on the display terminal of the master-control room, and an accumulated fatigue use coefficient curve, which changes along the time, can be outputted and can be used to evaluate the change trend of accumulated fatigue use coefficient of a monitored position.

Description

technical field [0001] The invention relates to nuclear-grade pipeline fatigue technology, in particular to a method for monitoring nuclear-grade pipeline fatigue using a strain sensor. Background technique [0002] During the service period of a nuclear power plant, fluctuations in operating temperature and pressure will cause alternating stress on nuclear-grade pipelines, and when the alternating stress reaches a certain level, fatigue damage will occur to nuclear-grade pipelines. In the design stage of the nuclear power plant, it is assumed that the operating transient experienced by the pipeline is the design transient. The design transient is more severe than the operating transient of the actual nuclear power plant, and the sequence of these design transients (that is, the transient history) is unknown, so the most unfavorable transient history can only be assumed in the fatigue design analysis of nuclear pipelines. This results in a very conservative cumulative fatig...

AI Technical Summary

Problems solved by technology

The design transient is more severe than the operating transient of the actual nuclear power plant, and the sequence of these design transients (that is, the transient history) is unknown, so the most unfavorable transient history can only be assumed in the fatigue design analysis of nuclear pipelines. resulting in a very conservative cumulative fatigue service factor from the analysis

In addition, NRC RG1.207 has clearly proposed that new nuclear power plants should consider the influence of environmental factors on the fatigue damage of nuclear-grade pipelines, which will further increase the conservatism of the cumulative fatigue service coefficient obtained from the analysis, and will greatly increase the economic efficiency of nuclear power plants. reduce

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