Improvement of the Damping Constants for Seismic Design of Piping System for NPP
- Tokyo Electric Power Company (Japan)
- Mitsubishi Heavy Industries Ltd. (Japan)
- Toshiba Corporation (Japan)
- Hitachi Ltd. (Japan)
- Ishikawajima-Harima Heavy Industries Company Ltd., 1 Shin-Nakaharacho, Isogoku, Yokohama 235-8501 (Japan)
The present design damping constants for nuclear power plant (NPP)'s piping system in Japan were developed through discussion among expert researchers, electric utilities and power plant manufactures. They are standardized in 'Technical guidelines for seismic design of Nuclear Power Plants' (JEAG 4601-1991 Supplemental Edition). But some of the damping constants are too conservative because of a lack of experimental data. To improve this excessive conservatism, piping systems supported by U-bolts were chosen and U-bolt support element test and piping model excitation test were performed to obtain proper damping constants. The damping mechanism consists of damping due to piping materials, damping due to fluid interaction, damping due to plastic deformation of piping and supports, and damping due to friction and collision between piping and supports. Because the damping due to friction and collision was considered to be dominant, we focused our effort on formulating these phenomena by a physical model. The validity of damping estimation method was confirmed by comparing data that was obtained from the elemental tests and the actual scale piping model test. New design damping constants were decided from the damping estimations for piping systems in an actual plant. From now on, we will use the new design damping constants for U-bolt support piping systems, which were proposed from this study, as a standard in the Japanese piping seismic design. (authors)
- Research Organization:
- The ASME Foundation, Inc., Three Park Avenue, New York, NY 10016-5990 (United States)
- OSTI ID:
- 21072729
- Country of Publication:
- United States
- Language:
- English
Similar Records
Current earthquake engineering practice for Japanese nuclear power plants
Quantification of margins in piping system seismic response: Methodologies and damping