Seismic stacking

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. 

The public consequences were significantly lower public than expected for a typical commercial LWR primarily because of the large distance to the public (>6 miles) and dispersal afforded by the height of the stack. The mean frequencies per year for offsite early fatalities are Internal Events 9.7E-13, Fire 3.8E-9, Seismic 2.2E-8, and Total 3.1E-9. For offsite latent cancer fatalities the results are Internal Events - 4.1E-3, Fire - 4.2E-3, Seismic - 6.0E-2, Total - 6.8E-2. For onsite early fatalities the results are Internal Events l.OE-6, Fire 8.3E-5, Seismic 8.6E-4, and Total 9 4E-4. For onsite latent cancer fatalities the results are Internal Events 2.70-4, Fire 2 3E-4, Seismic 3.0E-3, and Total 3.5E-3. 

Defects include (dust) particles on or within suspended interdigitated seismic masses, leading to electrical shorts and to deviations in moments of inertia. Another example relates to the appearance of crystallographic defects such as dislocations or stacking faults in epitaxial superstructures, causing leakage currents that might impair sensor reliability in the field. Defect densities may of course vary within a wafer, from wafer to wafer, and from lot to lot. Unfortunately, at present not many models are available that link tolerance bands of functional parameters to specific defects and their tolerable density distributions. 

The multiplet analysis provides information on the micro structures in the seismic cloud. However, it does not give knowledge of absolute locations of individual multiplet clusters with the same order of precision to the relative location of events in a multiplet cluster. Moriya et al. (2002) proposed the multiplet-clustering method" to reduce the location error of multiplet clusters using the technique of clustering analysis. In this method, the waveforms of events in a multiplet group are stacked, and similar phases of the stacked waveforms are compared in time domain. Then, relative arrival time differences (i.e. relative locations between the stacked events) are more precisely determined. 

In, = moment of inertia of pier, legs, stack, etc., in." E = modulus of elasticity, psi Sa— Sf = soil profile type from Table 3-9c Na, Nv = near source factor from Table 3-9d Seismic source type = from Table 3-9e... 

Stability and alignment of the reactor core components, as well as shielding for the Vessel System (VS), are provided by the permanent side reflector which consists of graphite blocks stacked to form a cylinder around the core, as shown in Figures 4.4-1 and 4.4-2. Radial restraint is provided to the core, through the PSR, by the core lateral restraint located between the outer side reflector and the reactor vessel. The core lateral restraint includes the core barrel with attached coolant inlet channels, and the core barrel seismic keys. 

As far as vertical slim vessels are concerned, the most common damages in case of seismic event are the failure at the foundation, due to the excessive stress, and the loss of contained fluids because of failure of connected flanges, due to excessive relative displacements. For example, during the Loma Prieta earthquake a refinery was seriously damaged, where the most important effect was on the anchor bolts of about 20 vertical vessels, on a total of 50 vessels. During the Valparaiso earthquake in a ventilation-stack with diameter 18" the anchor bolts were subjected to a similar damage, with the yielding of bolts. 

In case of emergency, gas supply is shut oR by reroute operation the Control Center. Seismic sensors are insteKed to enable automatic stHitdownintheeventof a nu r Vera Stack earthrfuake. 

The mechanical structure of a fuel basket or canister shall be designed to support, without structural deformity leading to handling problems, the mass of other fully loaded baskets or canisters which may be placed upon it if stacking is proposed. Static, impact and seismic loads shall be considered. 

Several investigators have examined the seismic response of classical monuments and, in general, of stacks of rigid bodies analytically, numerically, or experimentally, mostly using... 

Tracking Changes in Volcanic Systems with Seismic Interferometry, Fig. 8 The upper panel shows the relative travel time change for stacks of repeating explosions over the course of 20 days beginning on August 24, 2007. The number of Strombolian explosions per hour is plotted in the lower panel for comparison. The explosions occurred during a time period of elevated reduced displacement, as seen in Fig. 7... 

Horizons are usually seen as interfaces between subsurface layers of rocks of different properties. Thus reservoirs are discriminated in the depth extent from seismic cubes by their top and bottom horizons corresponding to their upper and lower limits, respectively. Horizons are usually manually or semi-automatically interpreted by analysing seismic data. However, new tools have recently emerged that allow an automated extraction of horizons from seismic. These new techniques are based on classification of a set of seismic waveform attributes along extrema (minima or maxima) in a seismic post stack cube. For further details on this, we refer to [4, 5]. 

This subsection addresses the evaluation of the models and methods used to develop the floor response spectra (FRS) used for piping and equipment seismic qualification and seismic loads acting on structures. All of the systems required for restart are contained in the reactor building, the stack building, the cooling water reservoir (186 Basin), and the process effluent sump structure. 

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