Inclusion of Aircraft Crash into NPP Design Bases and Probabilistic Justification of Loads on Civil Structures and Equipment

2020 ◽  
pp. 35-47
Author(s):  
Nikita Chernukha
Keyword(s):  
Nuclear Power ◽  
Response Spectra ◽  
Mechanical Action ◽  
Exceedance Probability ◽  
Civil Structures ◽  
Method Of Calculation ◽  
Floor Response Spectra ◽  
Aircraft Trajectory ◽  
Probabilistic Justification ◽  
Aircraft Crash

The article is about nuclear power plant (NPP) safety analysis in case of aircraft crash. Specifically, the article considers the following problems: inclusion of aircraft crash into NPP design bases regarding calculation of frequency of an aircraft crash into NPP; aspects of justification of loads on NPP structures, systems and components (SSCs) caused by mechanical action of a primary missile – aircraft fuselage impact. Probabilistic characteristics of such random parameters as frequency of aircraft crash and direction of aircraft trajectory are determined by the results of analysis of world statistics of aviation accidents. Method of calculation of aircraft crash frequency on structures, buildings and NPP as a whole is presented. It takes into account options of accidental and intentional aircraft crashes and various aircraft approach scenarios. Procedure of probabilistic justification of loads on civil structures under aircraft impact is described. The loads are specified so as not to exceed allowable value of failure probability of NPP as a whole. Calculation of failure frequency of civil structures of existing NPP is given as an example to show analysis in case of a crash of an aircraft heavier than considered in NPP design. Procedure of probabilistic justification of dynamic loads on NPP equipment in case of aircraft impact is described. Method of floor response spectra (FRS) calculation with the required non-exceedance probability is given. Probabilistically justified loads in case of intentional aircraft impact (act of terrorism) are also considered. Additionally it is presented how internal forces calculated with the use of FRS with the required non-exceedance probability can be summed to provide analysis of subsystems.

scholarly journals Seismic Responses of NPP Structures Considering the Effects of Lead Rubber Bearing

2020 ◽  
Vol 10 (6) ◽  
pp. 6500-6503
Author(s):  
D. D. Nguyen ◽  
C. N. Nguyen
Keyword(s):  
Cross Sections ◽  
Nuclear Power ◽  
Low Frequency ◽  
Time History ◽  
Response Spectra ◽  
Floor Response Spectra ◽  
Lead Rubber Bearing ◽  
Isolated Structures ◽  
Rubber Bearings ◽  
Lumped Masses

Abstract-This study investigates the effects of Lead Rubber Bearings (LRBs) on Floor Response Spectra (FRS) of Nuclear Power Plant (NPP) structures. Three main structures in the Advanced Power Reactor 1400 (APR1400) NPP including the reactor containment building, an internal structure, and an auxiliary building were numerically developed in SAP2000. The structures were modeled using beam stick elements, and lumped masses were assigned to beam element nodes. All equivalent section properties of beam elements were calculated based on the designed cross-sections of the structures. A series of 40 ground motions with response spectra scaled to match the NRC 1.60 spectrum were utilized in numerical time-history analyses. Finally, a thorough comparison of FRS was conducted at different elevations of the structures, considering both with and without LRB. Numerical results showed that the FRS of base-isolated structures at higher elevations was significantly reduced compared to non-isolated structures. However, at lower elevations, the FRS was higher for the base-isolated structures compared to the non-isolated ones. Additionally, at a low-frequency range, roughly smaller than 3 Hz, the FRS of base-isolated structures was always greater than that of the non-isolated ones.

scholarly journals Dynamic seismic analysis of nuclear power plant buildings and bearing stratum

2021 ◽  
Vol 31 (4) ◽  
pp. 79-88
Author(s):  
S. V. Koval ◽  
A. V. Kuzminov ◽  
P. A. Rodin ◽  
N. M. Sidorov
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Seismic Analysis ◽  
Seismic Loading ◽  
Response Spectra ◽  
Kinematic Parameters ◽  
Specialized Software ◽  
Floor Response Spectra ◽  
Calculation Results ◽  
Supporting Frame

Various approaches are used for simulating seismic loading and collaboration of a structure and a bearing stratum when carrying out dynamic seismic analysis in specialized software. In the present work, the kinematic parameters of various structures and bearing stratum were calculated using SCAD and STAR_T software. Seismic performance of a reference tower type supporting frame was calculated for 7 grade earthquake. As a result, the floor accelerograms were calculated, and the floor response spectra were built. The calculation results obtained by various methods and structure models were analyzed and compared.

Study on Piping Response Under Multiple Excitation: Part 2 — Validation for Multiple Excitation Analysis of Piping

2013 ◽  
Author(s):  
Satoru Kai ◽  
Tomoyoshi Watakabe ◽  
Naoaki Kaneko ◽  
Kunihiro Tochiki ◽  
Makoto Moriizumi ◽  
...  
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Nuclear Power ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Shaking Table ◽  
Response Analysis ◽  
Multiple Time ◽  
Floor Response Spectra

The piping in a nuclear power plant is laid across multiple floors of a single building or two buildings, which are supported at many points. As the piping is excited by multiple-inputs from the supporting points during an earthquake, seismic response analysis by multiple excitations is needed to obtain the exact seismic response of the piping. However, few experiments involving such multiple excitation have been performed to verify the validity of multiple excitation analysis. Therefore, analysis of the seismic design of piping in Japan is performed by the enveloped Floor Response Spectrum (FRS), which covers all floor response spectra at all supporting points. The piping response estimated by enveloped FRS is conservative in most cases compared with the actual seismic response by multiple excitations. To perform rational seismic design and evaluation, it is important to investigate the seismic response by multiple excitations and to verify the validity of the analytical method by multiple excitation test. This paper reports the validation results of the multiple-excitation analysis of piping compared with the results of the multiple excitations shaking test using triple uni-axial shaking table and a 3-dimensional piping model (89.1mm diameter and 5.5mm thickness). Three directional moments from the analysis and the shaking test were compared on the validation. As the result, it is confirmed that the analysis by multiple time history excitation corresponds with the test result.

Reanalysis of the floor response spectra of the Ignalina Nuclear Power Plant Reactor Building

2017 ◽  
Vol 324 ◽  
pp. 260-268
Author(s):  
Gintautas Dundulis ◽  
Rimantas Kačianauskas ◽  
Darius Markauskas ◽  
Eugeniuš Stupak ◽  
Stanislav Stupak ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Response Spectra ◽  
Floor Response Spectra ◽  
Reactor Building ◽  
Plant Reactor

scholarly journals Analysis of Seismic Soil-Structure Interaction for a Nuclear Power Plant (HTR-10)

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaoxin Wang ◽  
Qin Zhou ◽  
Kaixin Zhu ◽  
Li Shi ◽  
Xiaotian Li ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Soil Structure ◽  
Power Plants ◽  
Response Spectra ◽  
Seismic Excitation ◽  
Primary System ◽  
Fe Model ◽  
Floor Response Spectra ◽  
Fixed Base ◽  
Test Reactor

The response of nuclear power plants (NPPs) to seismic events is affected by soil-structure interactions (SSI). In the present paper, a finite element (FE) model with transmitting boundaries is used to analyse the SSI effect on the response of NPP buildings subjected to vertically incident seismic excitation. Analysis parameters that affect the accuracy of the calculations, including the dimension of the domain and artificial boundary types, are investigated through a set of models. A numerical SSI analysis for the 10 MW High Temperature Gas Cooled Test Reactor (HTR-10) under seismic excitation was carried out using the developed model. The floor response spectra (FRS) produced by the SSI analysis are compared with a fixed-base model to investigate the SSI effect on the dynamic response of the reactor building. The results show that the FRS at foundation level are reduced and those at higher floor levels are altered significantly when taking SSI into account. The peak frequencies of the FRS are reduced due to the SSI, whereas the acceleration at high floor levels is increased at a certain frequency range. The seismic response of the primary system components, however, is reduced by the analysed SSI for the HTR-10 on the current soil site.

Seismic Re-Evaluation of the Armenian NPP Unit 2: Issues and Engineering Approach

2002 ◽  
Author(s):  
Paruyr Zadoyan ◽  
Nikolaos Simos
Keyword(s):  
Nuclear Power ◽  
Site Response ◽  
Response Spectra ◽  
Soil Condition ◽  
Independent Study ◽  
Foundation Design ◽  
Power Utility ◽  
Current Effort ◽  
Floor Response Spectra ◽  
Safety Systems

As part of the overall effort of seismically upgrading the Armenian Nuclear Power Plant (ANPP) - Unit 2, the Armenian Nuclear Regulatory Authority (ANRA) with the technical support of the US NRC is performing a host of independent studies on key seismic issues associated with the nuclear facility. Specifically, by taking into account new information that has been generated by a number of sources on (a) the seismic hazards at the site, (b) the soil condition and layering, (c) the particularities of the reactor foundation design and its interface with the surrounding soil, and (d) structural details of the reactor and generator buildings, a comprehensive effort has been undertaken to independently establish floor response spectra that, in turn, better reflect the seismic reality at the plant. To accomplish the task of generating floor response spectra, that will be used in the seismic upgrade, detailed analyses focusing on (a) the site response using the capabilities of the SHAKE program, (b) the Soil-Structure-Interaction (SSI) aspect of the problem utilizing the SASSI and POROSLAM codes, and (c) the dynamic response of the reactor building through the use of the STARDYNE code were performed. The combined output of the various aspects of the analysis lead to a set of floor spectra at key locations on the structure so that the existing capacity of safety systems can be assessed as well as the need for upgrade to meet their revised seismic margins. While the current effort is work-in-progress, the paper presents preliminary results of this independent study and it attempts to make engineering comparisons with other on-going studies performed on behalf of the nuclear power utility in its effort to seismically upgrade the plant.

Floor Response Spectra of Loviisa NPP Reactor Buildings

2010 ◽  
Author(s):  
Jukka Ka¨hko¨nen ◽  
Pentti Varpasuo
Keyword(s):  
Material Properties ◽  
Nuclear Power ◽  
Ground Motions ◽  
Response Spectra ◽  
Primary Circuit ◽  
Fe Model ◽  
Floor Response Spectra ◽  
Modal Damping ◽  
Reactor Building ◽  
Circuit Components

For the updated seismic probabilistic risk assessment of the Loviisa nuclear power plant in Finland, knowledge of reactor building floor response spectra were needed. For this purpose a large finite element (FE) model of the reactor building was constructed. The model included all the major primary circuit components. The FE -model was parameterized and the Latin hypercube method was utilized to construct sixty samples of reactor building. Parameters used were material properties for concrete and steel, modal damping and the ground motion. The ground motions were derived from the seismic studies conducted for the Loviisa site. Following results were achieved in this analysis: The probabilistic spectra were determined for different elevations in the reactor building as well as for the representative locations in the main mechanical components that were explicitly modeled.

Analyzing and Comparing the Floor Response Spectra of the NPP Based on Different Soil Dynamic Numerical Models

2013 ◽  
Author(s):  
Xiu-yun Zhu ◽  
Rong Pan
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Seismic Design ◽  
Nuclear Power ◽  
Numerical Models ◽  
Response Spectra ◽  
Site Conditions ◽  
Design Codes ◽  
Floor Response Spectra ◽  
Soil Dynamic

The traditional soil dynamic impedance models, recommended by the main international seismic design codes of the nuclear power plant (NPP), are only expressed by a single parallel connection system of spring and dashpot which can not reflect the dynamic stiffness varying with excitation frequencies, and also can not simulate the cases of non-homogeneous site conditions. With the recent development of soil-structure interaction (SSI) analysis, based on the damping-solvent extraction method (DSEM) and the lumped parameter models recommended by seismic design codes of ASCE4-98,RCCG which are all applicable to the homogeneous site and also massless foundation model and viscous-spring artificial boundary model of especially fit for the numerical simulation of non-homogeneous site, comparative study of both the direct method and sub-structure method is carried out in this paper. Finally, by taking the analysis of floor response spectra (FRS) for a certain CPR1000 reactor building as an example, comparative analyses of homogeneous and layered site conditions using various soil dynamic numerical models above-mentioned are performed. In addition, in order to validate the accuracy, the calculated results are compared to that of SASSI program. The results show that FRS in the horizontal direction are good agreement regardless for the homogeneous and layered site conditions, the shapes of FRS in the vertical direction change obviously in the homogeneous site condition. This paper provides some guidance and reference in the aspect of evaluation the seismic suitability for the site of nuclear power plant (NPP).

Study on Piping Response Under Multiple Excitation: Part 1 — Triple Shaking Table Test of Piping Having Three-Supporting Points

2013 ◽  
Author(s):  
Tomoyoshi Watakabe ◽  
Naoaki Kaneko ◽  
Shigekazu Aida ◽  
Akihito Otani ◽  
Makoto Moriizumi ◽  
...  
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Nuclear Power ◽  
Shaking Table Test ◽  
Response Spectrum ◽  
Response Spectra ◽  
Shaking Table ◽  
Response Analysis ◽  
3 Dimensional ◽  
Floor Response Spectra

The piping in a nuclear power plant is laid across multiple floors of a single building or two buildings, which are supported at many points. As the piping is excited by multiple inputs from the supporting points during an earthquake, seismic response analysis by multiple excitations is needed to obtain the exact seismic response of the piping. However, few experiments involving such multiple excitations have been performed to verify the validity of multiple excitation analysis. Therefore, analysis of the seismic design of piping in Japan is performed by the enveloped Floor Response Spectrum (FRS), which covers all floor response spectra at all supporting points. The piping response estimated by enveloped FRS is conservative in most cases compared with the actual seismic response by multiple excitations. To perform rational seismic design and evaluation, it is important to investigate the seismic response by multiple excitations and verify the validity of the analysis method by multiple-excitation test. This paper reports on the result of the shaking test using triple uni-axial shaking tables and a 3-dimensional piping model (89.1mm in diameter and 5.5mm thickness). The piping model was fixed to three shaking tables, meaning three. Different inputs were possible. By the shaking test, dynamic behavior under multiple excitations was confirmed, and data to verify multiple-excitation analysis was obtained.

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