External Natural Event Research Team

Personnel

Approximately 60 researchers (Main Research Center: Abiko-area)

Research Fileds

External Natural Event Research Team is composed of eight specialized fields as follows.

Assessment of Capable Fault
Specialties of Members	Geology，Geomorphology，Seismology, Geochemistry, Geochronology, etc.
Main Research Topics	Evaluation of fault activity and geometry
Engineering Seismology
Specialties of Members	Seismology, Earthquake engineering, Geomorphology, Geophysics, etc.
Main Research Topics	Seismic ground motion and hazard assessment
Geotechnical Earthquake engineering
Specialties of Members	Geotechnical engineering, Geology, Seismic engineering, Reliability engineering, etc
Main Research Topics	Evaluation of fragility and risk for ground and slopes
Seismic Fragility of Structures
Specialties of Members	Concrete engineering, Structural engineering, Seismic engineering, Geotechnical engineering, etc.
Main Research Topics	Evaluation of seismic fragility and structural soundness for civil engineering structures
Seismic Fragility of Building and Equipment
Specialties of Members	Structural engineering, Reliability engineering, Earthquake engineering, Computational engineering, etc
Main Research Topics	Seismic fragility evaluations of nuclear building, equipment and piping system Seismic PRA of nuclear facilities / installations using a model plant
Tsunami Risk Assessment
Specialties of Members	Coastal engineering, Tsunami engineering, Geology, etc.
Main Research Topics	Evaluation of tsunami risk and impact
Extreme Weather Risk Assessment
Specialties of Members	Meteorology, Wind engineering, Fluid science, Structural engineering, etc.
Main Research Topics	Evaluation for tornado and other extreme meteorological risk and development of protective measures
Volcanic Risk Assessment
Specialties of Members	Geology, Volcanology, Fluid science, Meteorology , etc.
Main Research Topics	Evaluation of volcanic ash-fall risk

Main Research Facilities

• Large-scale Tsunami Physical Simulator
• Strong Shake Generator: Resonance-type shaking table
• Helical X-ray CT Scanner
• Centrifugal Vibration Table

Large-scale Tsunami Physical Simulator

　The large-scale tsunami physical simulator is a facility designed with the main purpose of assessing the impact resulting from a tsunami on a nuclear power generation facility, and is the only facility in the world capable of precisely reproducing on a large scale the water flow of a tsunami running up onto land.
　With this simulator, a wide variety and large number of tests have been conducted, including verifying the performance of installed barriers equivalent to actual seawall embankments inside a channel as well as measuring the force of debris impact ro structures by using full-scale vehicles.

Strong Shake Generator: Resonance-type shaking table

　In order to assess the seismic safety of components, pipes and equipments in nuclear power plants, CRIEPI has developed a novel shaking table with the capability to conduct vibration testing up to the peak acceleration of 20G. Such a highly-accelerated condition can be realized in this device by using resonance phenomena (which one can observe, for example, in building motion subject to earthquake or wind forces synchronizing with the inherent motion period of the building).
　Since the standard earthquake ground motion to be employed in seismic design has been updated more stringently, the response acceleration of the equipment tends to exceed the response acceleration that has been previously obtained in shaking tests for confirmation of safe operation at the locations where the equipment is mounted. Furthermore, from the standpoint of equipment fragility in earthquake PRA, fragility assessments need to be conducted to the extent such that extreme acceleration brings about actual damage in shaking tests. Based on these backgrounds, this strong shake generator is used to perform tests to verify such as the functionality of electric-actuated valves attached to pipes, etc.

Helical X-ray CT Scanner

　This scanner allows for a nondestructive three-dimensional analysis of the internal structure of rock formations, deposits and other samples. Currently, in assessments of tsunami as well as fault activity that focus on nuclear power facilities, three-dimensional structural analysis of fault fracture zones and tsunami deposits are being conducted. In addition, in order to clarify the origin and process of formation of geological structures in the ground which forms the foundation of nuclear power facilities, tests have been conducted with scale models of actual fault displacement. This scanner has provided a three-dimensional image of ground displacement of the scale ground.

Centrifugal Vibration Table

　In order to contribute to the development of seismic stability assessments of the foundation ground of a nuclear power facility and its surrounding slopes, a vibration table (unidirectional vibration) has been installed on the platform for the CRIEPI’s centrifugal base rock simulator platform. This enables simulation of the stress during an actual earthquake to be reproduced by imparting centrifugal force on a scale model of the foundation ground and surrounding slopes. This table is capable of reproducing an earthquake of 500gal - 1000gal with a 1/25th - 1/50th scale model of the ground. The size of the vibration table on which the model is placed is 30cm x 70cm, and the maximum payload is 500kg.