Seismic analysis

Using fire models, locations of equipment, heat transfer calculations, and environmental qualifications of the equipment, it is possible to estimate the time to failure. Fragility cuives that relate fire durations and equipment damage while considering the probability of fire suppre.ssion are produced to relate to the overall PSA. These fragility curves and their use is simitar the methods ised for seismic analysis. 

Seismic analysis of the containment, reactor building, and auxiliary building (including input and response). 

Method of seismic analysis and any limiting results or typical itructural calculations for seismically qualified equipment, a) Typical large exterior tank and three small interior tanks, b) Three different pumps, c) Valves. 

LLNL was contracted to use the results of the Seismic Hazard Characterization Project (SHCP). (NUREG/CR-5250) to calculate the seismic hazard at the SRS using methods similar to the Seismic Owners Group-Electric Power Research Institute (SOG/EPRI) and LLNL the (wo seismic hazard estimates for the SRS are different. The SHCP (Savy, 1988) seismic hazani results are typically within a factor of 5. Results of the seismic analysis are given in Table 11.3-6... 

Berkowitz, L., 1969, Seismic Analysis of Primary Piping Systems for Nuclear Generating stations, Reactor Fuel Proc. Technol. 12 p 267. 

C.H. CHEN (Editor) — COMPUTER-AIDED SEISMIC ANALYSIS AND DISCRIMINATION... 

Gaucher, E., Comet, F. H. and Bernard, P. (1998), Induced seismicity analysis for structure identification and stress field determination. Paper SPE 47324, Proc. SPEdSRM, Trondheim, Norway. 

To produce the seismic analysis model for the reactor internal structures, the lumped-mass modeling technique is used From the 3-dimensional finite element model of KALIMER reactor internal structures, the detail local stiffness analyses are performed to construct the lumped-mass seismic analysis model The seismic analysis and evaluation of KALIMER are presented through the modal analysis, the seismic time history analvsis, and the equivalent seismic stiess analysis Table 3 shows the natural frequencies of the reactor structures resulted from the modal analysis for the seismic analysis model shown in Fig 13... 

The seismic analysis of LMR core structures is a complex problem involving the dynamic interaction of many hundreds of individual fuel, blanket, and shield assemblies m a sodium environment. To simplify the core seismic problem, the cluster modeling technique sho vn in Fig. 14 for a diametral row of the core is used. The clusters of assemblies are assumed to have no relative motion between the assemblies within a cluster. The diametral row modeling approach gives conservative results and it is easier to evaluate the core seismic behavior compared to a full core model using the cluster technique. 

Fig. 14. Clustering of LMR Core Assemblies Fig. 15. Simplified Core Seismic Analysis Model...

To investigate the dynamic characteristics of LMR core seismic analysis model shown in Fig. 15, the modal analysis is carried out. To generate the linear model used in modal imalysis, all the gap stifihess shown in Fig.4 are eliminated. The results of modal analysis show that the fundamental frequency of LMR core is 4.3 FIz and the second natural frequency is 24.3FIz. These natural frequencies of core will show non-linear behavior during impacts at load pads. 

Yoo, B, Lee. J H and Choi, IK, Seismic analysis modeling and seismic response analysis of KALIMER reactor building, KAERI/TR-1062/98, (1998)... 

It is the Intention to follow current light water reactor (LWR) seismic analysis and design practice wherever applicable. This section covers... 

The seismic requirement for the MHTGR plant is to develop a standard plant design which could be sited on 85 percent of the prospective U.S. sites. To satisfy this requirement, over 100 prospective U.S. sites were surveyed and the appropriate seismic parameters were developed and Incorporated into the seismic analysis to form the basis for the conceptual design. 

When a specific site is identified and the required seismologic and geologic data are developed, a site-specific seismic analysis will be performed culminating in preparation of floor response spectra (FRS). These will be compared with the Standard MHTGR FRS to assure that the site-specific FRS are bounded by the Standard FRS. 

The general analytical methods used in the plant seismic analysis are, except where noted in the following discussion, consistent with current LWR practice. (Ref. 5) The initial analysis described below were performed for the QBE as this is more limiting than the SSE. In these analyses, seismic waves are assumed to propagate vertically. The effects of inclined seismic waves (dependent on fault locations) and building interactions (dependent on the number of modules) are considered site-specific. These effects will be accommodated when site-specific analysis are performed. Also, these analyses include the consideration of codirectional responses from simultaneous time history inputs in three directions. 

The plant seismic analysis approach is divided into two phases ... 

In the second phase of the seismic analysis, the MHTGR Reactor Building and NSSS were analyzed for the three representative sites. These analyses were performed using the SASSI computer program. (Ref. 6) The objective of the SASSI analyses were to develop envelopes for the three representative sites. These envelopes Included ... 

For these items, the procedures and criteria used for seismic analysis are comparable to those committed to in recent LWR Final Safety Analysis Reports (FSARs). 

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 CLR structure was designed to achieve tangential stiffness and a frequency in excess of 20 Hz during an OBE event to maintain structural integrity. Seismic analysis was performed with two-dimensional special... 

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. 

Douglas, B.M.(1976) Quick Release Pullback Testing and Analytical Seismic Analysis of a Six-Span Composite Girder Bridge. Report FHWA-RD-76-173, Federal Highway Administration Offices of Research and Development, Washington D.C., pp.73. 

Cancellara D., De Angelis F. (2012)—Seismic analysis and comparison of different base isolation systems for a multi-storey RC building with irregularities in plan. Advanced Materials Research, Vol. 594-597, pp. 1788-1799. 

Even with this simplification, the problem of defining the seismic ground motion as an input datum in the seismic analysis of the plant is far from trivial here too some conventionally accepted and usually conservative assumptions are necessary (Castellani et al., 2000 Roesset, 1995). 

Often it is impractical to model, in the seismic analysis of a plant, all the components located at different heights. The need arises to define methods of identifying a seismic excitation (spectrum or accelerogram) by which resistance and functionality of the essential components can be verified. In reality, recently the problem has been simplified by the development of dynamic analysis computer programs, which makes the modelling of structure-component complexes easier. 

ASCE (1986) Seismic analysis of safety-related nuclear structures and commentary on standards for seismic analysis of safety-related nuclear structures , ASCE Standard ASCE 4-86, New York. 

Livolant, M., Petrangeli, G., Shibata, H., Idriss, I.M. and Stevenson, J.D. (1979) Seismic analysis and testing of nuclear power plants , IAEA Safety Series N.50-SG-S2, Vienna. 

Shah, H.H. and Chu, S.L. (1974) Seismic analysis of underground structural elements . Journal of Power Division, ASCE, 100(POl). 

ARl 70 Benchmark study for the seismic analysis and testing of WWER-type NPPs, No. 1176,... 

F. Dempsey, 1992, Seismic Analysis of the Hot Cell Facility, Sandia National Laboratories,... 

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