Seismic analysis code

Seismic analysis method development and verification on FBR core in the framework of "lAEA/IWGFR Coordinated Research Program on Intercomparison of LMFBR Seismic Analysis Codes" was completed in 1995. From 1996 PNC joins SYMPHONY program on FBR core seismic tests and analysis at CEA, France. 

The seismic analysis of the core is performed with the two-dimensional special purpose computer codes CRUNCH-2D and MCOCO, which account for the non-linearities in the structural design. Both CRUNCH-2D and MCOCO are based on the use of lumped masses and inertia concepts. A core element, therefore, is created as a rigid body while the element flexibilities are input as discrete springs and dampers at the corners of the element. CRUNCH-2D models a horizontal layer of the core and the core barrel structures (Figure 3.7-7). The model is one element deep and can represent a section of the core at any elevation, MCOCO models a strip of columns in a vertical plane along a core diameter and includes column support posts and core barrel structures (Figure 3.7-8). The strip has a width equal to the width of a permanent reflector block. Both models extend out to the reactor vessel,... 

The Vessel System, including the support subsystem, is analyzed using the NSSS finite-element model and response spectra input generated by the plant seismic analysis discussed in Section 3.7.2. This three-dimensional finite-element model is based on the Vessel System arrangement and is shown in Figure 3.7-6. The analysis is performed using the ANSYS computer code and the analysis procedures discussed in Section 3.7.3.1.1. (Ref. 11)... 

The MCSS is designed for high stiffness in order to maintain structural integrity during an SSE event. The seismic analysis indicates that the fundamental frequency is 32 Hz and a spectrum load of approximately 0.5 g. Comparison with ASME Boiler and Pressure Vessel Code Section III, Div. 1, Subsection NG stress criteria demonstrates that failure of the structure is not credible. 

In its review procedures, NRC has shown particular interest in the criticality, cooling, and seismic analysis in addition to the design and quality assurance specifications and codes. 

Mata, R, Oiler, S., Barbat, A.H. Boroschek, R. 2006. Numerical code for seismic analysis of structures incorporating energy dissipating devices. First European Conference on Earthquake Engineering and Seismology, ECEES, Geneva, Switzerland. 

The challenges that remain are in actually proving that releases absolutely cannot occur (given it is hard to prove a negative and such data are scarce) and that all potential core damage states are either avoided and/or adequately cooled. The methods used include SA analysis codes structural failure mode analysis radionuclide transport in buildings and the environment historical geotechnical, hydraulic, and seismic response analysis and PRAs. 

Perform seismic free-field soil column analysis and obtain the acceleration response spectrum at the base of the wall using a free-field analysis code such as SHAKE91 (Schnabel et al. 1972) taking into account soil nonlinearities with input motion specified at the ground surface or at the depth of foundation base mat,... 

In order to determine the factor by which damage is changing and the complexity of codes, a significant review and analysis was undertaken to create a harmonized up-to-date list of locations where seismic-resistant codes have been considered. There were several early initiatives which attempted to tmdertake this by looking at only a list of some of the countries worldwide with seismic-resistant building codes, including the World List initiative by the lAEE which includes details as to some seismic-resistant codes in various cotmtries - USEE... 

By contrast, historical earthquakes only can be explored by macroseismic analyses, and intensi is the only parameter that allows an estimate of the earthquake size to be made. Experience gained from the macroseismic analyses of instrumental events led to the development of empirical relationships in order to approximately estimate the moment magnitude (Mw) of historical events from earthquake intensity distribution. As a result, instrumental records are in the best case available from the first half of the twentieth century however, historical intensity analyses (extended in some regions back to the sixth to seventh century B.C.) are behind most of the seismic hazard analyses, seismic-building codes, and nuclear regulatory guides worldwide. Therefore, the use and refinement of intensity scales in earthquake analysis is stiU, and will continue to be, imperative to the society. 

Response Spectrum Modal Analysis in Seismic Design Codes... 

Structural Design Codes of Australia and New Zealand Seismic Actions Time History Seismic Analysis... 

A dynamic analysis of record was performed by United Engineers Constructors (UE C) for the SSS in the K-Reactor building. The UE C report, which is preliminary, documents the seismic analysis of the Far Side SSS piping for the K-Reactor. The 1983 B31.1 code was used in this analysis supplemented by the 1983 ASME Section III, Subsection NC for flanges. The faulted limits were used. UE C concluded, as a result of the analysis, that the Far Side SSS for the K-Reactor meets the specified stress criteria provided that recommended support modifications are made to the supporting system. By similarity, UE C concluded that the Near Side SSS for the K-Reactor also meets the specified stress criteria provided that similar modifications are made in accordance with UE C recommendations. 

ISK, a code for seismic risk analysis using faults as earthquake sources, developed by Guire, 1978. 

The Seismic Safety Margins Research Program developed a computer code called SMACS (Seismic Methodology Analysis Chain with Statistics) for calculating the seismic responses of structures, systems, and components. This code links the seismic input as ensembles of acceleration time histories with the calculations of the soil-structure interactions, the responses of major structures, and the responses of subsystems. Since uses a multi-support approach to perform the time-history response calculations for piping subsystems, the correlations between component responses can be handled explicitly. SMACS is an example of the codes that are available for calculating seismic response for PSA purposes. 

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