Press Release Back Number(2007)

Terminology

February 21, 2007
Chubu Electric Power Co., Inc.

Main text


  • • Standard ground motion Ss:
    Ground motion that is extremely rare but possible within the useful life of a facility, as seen in terms of seismology and seismic engineering (including considerations of geology, geological structure and earthquake activity in the vicinity of the site), and of which it is appropriate to anticipate major impact to facilities.

Attachments


  • • Seismic safety assessment of buildings and structures critical to seismic resistance design (equipment, piping systems and important outdoor structures):
    An assessment, based on "seismic safety assessment procedures", of whether buildings and structures critical to seismic resistance design (equipment / piping systems / important outdoor structures) maintain their safety function in the event of standard ground motion Ss.

  • • Reactor building foundation ground stability assessment:
    An assessment of whether the reactor building foundation ground supporting buildings and structures containing facilities and equipment critical to seismic design has sufficient capacity to support those buildings and structures in the event of the seismic force of standard ground motion Ss.

  • • Consideration of earthquake-caused phenomena (stability of area slopes):
    An assessment to make sure that slopes that could have a major impact on buildings and structures containing facilities and equipment critical to seismic design will not cause a collapse that would have a major impact on the safety function of facilities in the event of the seismic force of standard ground motion Ss.

  • • Consideration of earthquake-caused phenomena (safety during tsunamis):
    An assessment of the risk of the facility's safety functions sustaining major impact in the event of tsunamis, though they may be extremely rare but should be considered possible within the useful life of a facility.

Reference 1


  • • Decided ground motion with identified center for each site:
    Of earthquakes occurring in the area of the site, decided ground motion when studying characteristics of past earthquakes, active faults and plates and assessing earthquake patterns.

  • • Decided ground motion without identified center:
    Ground motion that should be considered in all cases, regardless of results of detailed surveys in the vicinity of the site. This is because even detailed studies that take vicinity conditions sufficiently into account cannot be claimed to be able to assess in advance all earthquakes in the continental crust that could potentially occur in the vicinity of the site.

  • • Where activity could not be ruled out since the latter Pleistocene:
    The active faults taken into account in seismic resistance design are those where activity could not be ruled out since the latter Pleistocene; geological strata or the topographical surface from the last interglacial epoch (from about 130,000 to 80,000 years ago) and before then are used to verify these. The latter Pleistocene is the geological era from about 130,000 to 10,000 years ago.

  • • Tectonic topography:
    A discipline for studying and learning the distribution of active faults using aerial photos of characteristic topography resulting from changes in the earth's crust because of active faults.

  • • Geophysics:
    A discipline for studying underground geological structures and properties using seismic waves, magnetism, gravity, etc.

  • • Seismic reflection surveying:
    A technique used for geophysical surveys. Vibrations are artificially induced that travel from the ground surface downward. The wavelength reflected from the stratum below is observed and analyzed to determine the geographical structure underground. This is a very up to date technique that has come into use for studying faults since the Great Hanshin Earthquake and Western Tottori Earthquake.

  • • Form of earthquake generation:
    Investigated earthquakes are chosen by classification, based on the form in which they were generated, such as: earthquakes in the continental crust, interplate earthquakes, subducting marine intra-plate earthquakes, subducted marine intra-plate earthquakes (intra-slab earthquakes), etc.

  • • Investigated earthquake:
    An earthquake predicted to have a major impact on the site, selected to help decide on the "decided ground motion with identified center for each site."

  • • Ground motion assessment with response spectrum technique:
    A method of assessing ground motion based on the relationship between earthquake magnitude and distance from its center.

  • • Ground motion assessment with fault modeling technique:
    A method of assessing ground motion based on modeling the fault movement that causes the earthquake.

  • • Model taking uncertainty into account:
    A model based on the basic model but with uncertainty taken into account.

  • • Basic model:
    A fundamental earthquake center model established based on past research results, etc. and the latest knowledge.

  • • Destruction starting point:
    During an earthquake, the point at which something fixed first starts to slide. Destruction of a fault plane begins at the destruction starting point and gradually spreads over the fault plane over time.

  • • Acceleration:
    A ratio expressing the change in speed of ground tremors caused by ground motion within a certain amount of time. Acceleration is expressed in units of gal (cm/s2)

  • • Acceleration wave:
    The extent of ground motion acceleration plotted over time on a graph.

  • • Response spectrum:
    An illustration of the type of tremors that ground motion generates in a building, plotted on a graph. The figure shown in Reference 1 plots a speed response spectrum on a graph so that the data can be read as both an acceleration response spectrum and a displacement response spectrum at the same time; this is referred to as a tripartite response spectrum. Tripartite response spectrums are shown on a logarithmic scale, with the horizontal axis representing cycle, the vertical axis the speed response spectrum, the 45° axis that goes up toward the left the acceleration response spectrum and the 45° axis that goes up toward the right the displacement response spectrum.

  • • Virtual Tokai earthquake:
    A fault model of an anticipated Tokai earthquake, based on the fault model of the Central Disaster Prevention Council, taking earthquake focus uncertainty into account and placing asperity directly under the power station site.

  • • Virtual Tokai earthquake / Tonankai earthquake / Nankai earthquake:
    A fault model of the anticipated Tokai earthquake portion of the earthquake focus regions for the anticipated Tokai earthquake / Tonankai earthquake / Nankai earthquake, based on the fault model of the Central Disaster Prevention Council, taking earthquake focus uncertainty into account and placing asperity directly under the power station site.

  • • Empirical Green's function method:
    A procedure for calculating the tremors of a large earthquake by adding together, as element earthquakes, those small earthquake observation records that are appropriate to use for ground motion assessment calculation (this is known as an empirical Green's function).This procedure requires appropriate observation records from assessment sites from small earthquakes occurring near the earthquake focus fault plane being assessed.

  • • Statistical Green's function method:
    A procedure for calculating the tremors of a large earthquake by statistically processing past observation records instead of appropriate small earthquake observation records, artificially creating a time record wave form (called a statistical Green's function), and adding these together, as element earthquakes.

Reference 2


  • • S Class:
    Pertaining to equipment that contains radioactive materials itself or is directly connected to facilities that contain radioactive materials, and which could leak the radioactive material if it malfunctions; equipment needed to prevent this situation from happening; and equipment needed to mitigate the impact of leaked radioactive material in the event this situation happens, when the impact is great.(examples: control rods, reactor cooling equipment, reactor pressure containers, etc.)

  • • B Class:
    Pertaining to equipment with a relatively small impact in the above.(examples: waste treatment equipment, main steam turbines, etc.)

  • • C Class:
    Equipment other than S Class and B Class, needing only to maintain the same level of safety as ordinary industrial equipment.