The Findings from the survey of crush zones at the fast breeder prototype reactor Monju site

Ishimaru, Tsuneari ; Shimada, Koji   ; Sueoka, Shigeru   ; Yasue, Kenichi; Niwa, Masakazu   ; Umeda, Koji

The Nuclear Regulation Authority (NRA) instructed to develop a further additional research plan regarding the crushed zones on the Monju site against the JAEA on September 25, 2013. The JAEA developed a research plan in response to this instruction, and, the stripping investigation with expansion of the area, the additional detailed geographical and geological surveys in the mountains/terrace boundary, and the marine seismic surveys in the coastal waters, were conducted. And, the JAEA was submitted to the NRA "Compilation Report" on March 28, 2014. From the investigation results so far, no clear evidence was observed to support that the on-site crushed zones are active faults. And, in the sea and land vicinity of the site, other than to the Shiraki-Nyu active fault, structure associated with the active fault is not recognized. From the plastic deformation of the biotite which is observed in the latest shear plane, the on-site crushed zones are considered to be a geological structure of the pre-Quaternary, which is formed in the deep underground environment of the several kilometers.