This study designed a specimen that simulates the deformation and failure behaviors of the piping components in nuclear power plants (NPPs) under excessive seismic loads beyond the design basis, and conducted ultimate-strength tests using this specimen at room temperature (RT) and 316 °C. SA312 TP316 stainless steel (SS) and SA508 Gr.3 Cl.1 low-alloy steel (LAS) were used in the experiments. Displacement-controlled cyclic loads with constant and random amplitudes of load-line displacement (LLD) were applied as input loads. A set of input cyclic loads consisted of 20 cycles, and the LLD amplitudes of the cyclic load were determined to induce the maximum membrane plus bending stress intensity of 6-42Sm on the specimen, where Sm is the allowable design stress intensity. Multiple sets of input cyclic loads, with increasing amplitude of LLD, were applied to the specimen until cracking initiated. The results demonstrate that the simulated specimen adequately showed the ratcheting deformation and fatigue-induced cracking of piping components under displacement-controlled excessive seismic loads. In addition, samples of both materials failed under displacement-controlled cyclic load levels that were several times higher than those of the design basis earthquake (DBE). The SA316 TP316 SS had greater resistance to failure under large-amplitude cyclic loads than did SA508 Gr.3 Cl.1 LAS. For both materials, resistance to failure was lower at 316 °C than at RT. This study confirmed that the evaluation procedure of the ASME design code predicted the fatigue failure of specimens very conservatively under large-amplitude cyclic loads simulating displacement-controlled excessive seismic loads.
|Journal||Journal of Pressure Vessel Technology, Transactions of the ASME|
|Publication status||Published - 2020 Oct 1|
Bibliographical noteFunding Information:
This work was supported by the KOREA HYDRO & NUCLEAR POWER CO., LTD. (No. 2017-13) and by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20184030202180).
© 2020 American Society of Mechanical Engineers (ASME). All rights reserved.
- deformation and failure behaviors
- displacement-controlled cyclic loads
- excessive seismic loads
- nuclear piping components
- simulated specimen
- ultimate-strength tests
ASJC Scopus subject areas
- Safety, Risk, Reliability and Quality
- Mechanics of Materials
- Mechanical Engineering