IEC/IEEE 60980-344:2020 pdf download – Nuclear facilities – Equipment important to safety – Seismic qualification.
3.7 correlation coefficient function comparative relationship between two time histories , as a function of time delay N ote 1 to ent ry: It pr ovides a statistical estimate of how much two motions are related , as a function of time delay. N ote 2 10 enlry: The numerica l range is fr om – 1 , 0 f or inversely relaled molions , zero for unrelaled , 10 +1 , 0 for re l aled motions. 3.8 critical d a mping least amount of viscous damping that causes a single-degree-of-freedom (SDO F) system to return to i ts or iginal position without oscillation after initial disturbance [SOURCE: I EEE Standards Dictionary Online] 3.9 critical seismic characteristic s design , material , and performance characteristics of an equipment item that provide reasonab le assurance tha t the item will perform its required function under seismic l oads 3. 10 cutoff frequency frequency in the response spectrum where the zero pe r iod acceleration (ZPA) asymp t ote begins N ole 1 to enlry: This is Ihe frequency beyond which Ihe sing le-degree-of-freedom (SDOF) oscillalors exhibit no ampl ificalion of mol i on and indicales Ihe upper lim il of Ihe frequency conlenl of Ihe waveform being ana l ysed 3.11 damping energy dissipation mechanism that reduces the ampl if ication and broadens the vibratory response in the region of r esonance N ole 1 10 enl ry: 1I is usually expressed as a percenlage of crilical damp i ng.
3.21 independent items components and equipment tha t: a) have different physical char acte ristics , or b) experience different sei smic motion characteristics , e.g. , different earthquakes , different sites , different buildings , or dif f erent orientations/locations in the same building 3. 22 median-centered in-structure response spectrum in-structure response spect rum deve loped using realistic damping and best estimate modeling parame ters to obta in the most probab le structural amplificat ion that could realist i cally occur for the level of the spec ified earthquake ground motion 3.23 narrowband response spectrum response spect rum that desc ribes the motion in which amplified r esponse occurs over a limited (nar row) range of frequencies 3.24 natural frequency frequency( ies) at which a body vibrates due to its own physical characteristics (mass and stiffness) when the body is distorted in a specific direction and then released 3.25 basis earthquake earthquake that could reasonably be expected to occur at the plant site during the operating life of the plant conside ring the. regional and local geo logy and seismology and specific characterist ics of local subsurface material N ote 1 to ent ry: It is that earthquake that produces the vibratory ground motion for which those features of the nu cl ear power plant , necessary fo r continued ope r at i on without undue ri sk to the hea l th and safety of the publ ic , are designed to rema in functiona l. 3.26 performance requirement requir ement that imposes per for manc e characteristics (conditions) on th e functional and structural requirements of the equipm ent or system