Nuclear Power Information
Provisions against Potential Massive Earthquakes
Basic Seismic Designs
In earthquake-prone Japan, nuclear power plants are taking various measures to assure its seismic safety. Besides those measures, the nuclear power plants are making a continuous effort to achieve a higher standard of safety; as new scientific/technical findings are acquired, they will be incorporated into the safety measures for all the nuclear power plants around Japan.
The plant design has been configured based on thorough investigation so that the plant can withstand the maximum earthquake ground motion.
The major facilities of a nuclear power plant are designed so that they can withstand the maximum level of earthquake that can be assumed considering past earthquakes and the result of thorough geological investigation.
[Methods of Investigation]
Boring survey, surficial geological investigation, trench excavation survey, offshore acoustic exploration, literature survey, aerial photographic interpretation, airborne gravity survey, etc.
Demonstration of seismic safety and identification of seismic safety threshold
Vibration tests are conducted using a world’s largest-class shaking table to demonstrate the seismic safety of safety important components, such as the containment vessel.
The seismic safety of a safety-important component is verified by applying a greater seismic force than that assumed in the design stage to a full-scale model or a finely-detailed model loaded on a shaking table.
A nuclear power plant is built on a robust foundation.
A nuclear power plant is built on a foundation, which is ensured with sufficient supporting functions by digging deep into the ground rather than on a subsurface ground on which wobbles by an earthquake will be significantly amplified.
The nuclear power plant will automatically shut down in response to a strong earthquake ground motion.
Multiple seismoscopes are installed at a nuclear power plant.
When a seismoscope detects a large seismic acceleration, it sends a signal to the control device which automatically shuts the reactor down in a safe manner.