Damping measurement method by using acoustic frequency comb

Nishida, Akemi  ; Suzuki, Yoshio   ; Hasegawa, Ken; Hayashi, Sachiko; Kunitomo, Takahiro*; Kumazawa, Mineo*; Hasada, Yoko*

Reliable and strict evaluation is demanded to guarantee the safety of nuclear facilities against earthquake vibrations, in particular. Usually the necessary data have been acquired by determining the natural frequency, the natural mode and attenuation characteristics by utilizing microseisms as an excitation agent of the vibration. The presence of measurement errors and estimation bias has been inherent and problematic in this approach. Here we try to make a break through by introducing ACROSS technology, which have been providing very accurate and reliable data on subsurface, i.e., geologic targets. In this presentation, we present the relevant strategy, general concept of this approach. The technical subjects on measurement system and also a potential method of analyzing data are presented, too. Some parts of this research result were obtained as the results of the JAEA director's fund for research and development in 2008.