The Case study of activities for safety of Onagawa Nuclear Power Plant

Yoshinaka, Kazuyuki

Gijutsushi, 29(11), p.12 - 15, 2017/11

AA2017-0334.pdf:0.47MB

We visited Onagawa NPP and discussed with the workers, for study of good practices at this plant, avoided severe accident, when the 3.11 earthquakes and tsunami disaster occurred. It was learned a part of background of the good practices, by discussion about organizational culture included in attitude for safety, philosophy of management, inheritance technology, and so on. It is important that we inform the knowledge leading safety culture analyzed from their experience to public, as professional engineer.

A Study of uplifts and subidences (5)

Takano, Toyoji*; Sasaki, Yutaka*; Fuse, Keisuke*; Saito, Akira*; Sato, Yoshikazu*

PNC TJ1454 96-001, 295 Pages, 1996/03

PNC-TJ1454-96-001.pdf:15.79MB

None

Identification of an event deposit in the Miyazaki Plain based on chemical composition of volcanic glass

Kagami, Saya; Niwa, Masakazu; Umeda, Koji*; Danhara, Toru*; Fujita, Natsuko; Nakanishi, Toshimichi*; Kamataki, Takanobu*; Kurosawa, Hideki*

no journal, , 

The Kikai-Akahoya (K-Ah) volcanic ash from the 7.3 Ka Kikai caldera eruption is one of the representative tephra of the Quaternary. We newly found the event deposit associated with the tsunami of the K-Ah eruption in the core (MMS1) from the Miyazaki Plain. Here, we present the results of tephra analysis and C dating of samples in the MMS1 core. The sediments between 10.4 m and 12.0 m in depth contained volcanic glasses and pumices that developed planar lamination with sand, indicating that tephra was deposited secondarily as submerged sediments. A previous study founded the similar sediments in a river near the boring site and interpreted to be deposit of tsunami during the 7.3 Ka Kikai caldera eruption. The results of C ages and identification by chemical composition and refractive index of volcanic glass are consistent with the assumption that the sediments between 10.4 m and 12.0 m in depth were tsunami sediments related to the K-Ah eruption. Chemical composition of volcanic glass in the K-Ah tephra is bimodal: 65wt.% (Type L) and 75wt.% (Type H) of SiO concentration. Previous studies suggested that Type H erupted in the early K-Ky eruption, and then the magma mixed with Type L erupted in the late K-Ky eruption. The samples contained the K-Ah volcanic ash in this study consist of mainly Type H and slightly Type L. Type H from 11.810.2 m depth was subdivided into two clusters and that from 12.3 m depth contained only one cluster of higher SiO concentration. The feature of the volcanic glasses may indicate the change in magma composition during the eruption.