Seismic Events

WASH-1400 did not analyze seismic events, but if they had, the risk they assessed would have been larger. Earthquake analysis was part of the FSAR for licensing a plant and had been practiced for some time before the RSS. This analysis included earthquake frequencies from historical records, ground-coupling models to estimate the intensity and frequency spectrum of the acceleration, and spring-mass models to estimate the forces on plant components under the 

Avalanche Excluded by siting considerations Flooding Plant specific requires detailed. Mudy 

Drought Excluded by assuming that there are multipie sources of the ultimate heat sink or that the ultimate heat sink is not affected by drought (e.g., cooling tower with adequately sized basin) Low lake Internal or river water Ultimate heat. sink is designed for at ii.-av. 30 days of operation 

External Hooding Site specific requires detailed study Low winter lemperature Thermal stresses and embriirlcn icr.i. irc cmcred by design codes and stardijrLK ii i also see ice.  

Extreme V. i(]-.is and lofTiadoes Site specific requires detailed study Meteorite All sites are equally susceptible 

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Fig 5.1-6 Large LOCA Seismic Event Tree for a i. some of which had been regarded as independent and redundant. Although there is little... 

Seismic Events Full Power NUREG-1150/y LLNL 1.2E-4 33... 

A seismic event three times or more the 0.25 g safe shutdown earthquake was the only significant mechanism found to cause oxidation of the graphite moderator stack. 

Uncovering and heatup of the core requires a much larger number of tubes to be broken at the seal table than are postulated to break as a result of a seismic event. 

Fuca Ridge geochemical controls in the aftermath of June 1999 seismic events. Journal of Geophysical Research, 108, 2429-2452. 

Fig. 4. Seismic events during injection in relation to time and distance from the injection source (from Shapiro et at. 2003).

In addition, the reliability of the refrigeration equipment and the provision of spare machines and backup power must be considered. This becomes especially important in locations where hurricanes, seismic events, tornadoes, and ice storms are possible. However, with proper design and maintenance, a refrigeration system can be highly reliable. 

The location of a seismic event, explosion or earthquake, is calculated from the chronometry of the seismic waves received by many stations surrounding the epicentre as well as possible. 

The primary network station is made up of 50 stations (see Table 13.1). It transmits data continuously to the International Data Center in Vienna and it is made up of three-component stations and array stations. Three-component stations are seismic stations with sensors that measure the three components (one vertical and two horizontal) of the arriving waves from seismic events, including earthquakes and explosions. These data enable the location and the size of the seismic event to be determined. They are not as sensitive as array stations but are less expensive. 

There exists a handful of documented cases where the Rn flux in the soil could not be explained by diffusional transport. Perhaps the most striking of these is the one reported by Gabelman (1974) from a detailed Rn survey across the Starks Salt Dome, Louisiana. During a period of 19 months and when 24 hour, 6 hour and 2.5 hour cycles were being observed, on the morning of 17 December 1971 the Rn content at one station unaccountably rose from about 200 pCi/L to 2140 pCi/L in three hours and then fell as rapidly to 50 pCi/L. One possible explanation may be the influence of an unnoticed seismic event. Alekseev et al. (1959) were able to explain most of the observed Rn concentrations using the diffusional transport model but in a few cases Rn penetration was found to be larger than expected and attributed to convective transfer of Rn. 

At mid-ocean ridges, seawater penetrates deeply into layers 2 and 3 of the newly formed oeeanie crust along cracks and fissures, which form in response to thermal contraction and seismic events in zones of active seafloor spreading (Fig. 13.2). The seawater cirenlating throngh the oceanic crust at seafloor spreading eenters is converted into a metal-bearing hydrothermal fluid in a... 

Asanuma et al. (2001) proposed a modification to the collapsing method. In this modified method the movements of the locations are dependent on the shape of the distribution of the seismic events within the confidence ellipsoid, and not just the... 

Acoustic Emission (AE) is a low energy seismic event. A seismic event can be considered as sudden inelastic deformation within a given volume of rock that radiates detectable seismic waves. A seismic event may be induced by fracture initiation, fracture propagation, or a sudden movement of existing fractures. 

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