Study Onpractical Analysis Method Of The Inner Containment In Nuclear Power Plant Reactor Building

In order to study the seismic behavior and damage mechanism of innercontainment of nuclear power plant, it is necessary to develop some practical dynamicanalysis methods to do the relevant research. A practical method based on the finiteelement method, and two practical simplified analysis methods are provided in thisthesis.Withthe finite element method, detailed analysis can be made on structuredynamic characteristics and seismic performance. With these simplified methods, thebasic dynamic characteristics and result of response spectra analysis ofnewly-designedand newly-introduced inner containment structure can be obtainedrapidly. Consequently, it’ll be convenient to check results of finite element modelanalysis with the resultsobtained through practical simplified analysis methods.Themain research work is shown as follow.1. The analysis of Inner containment structure dynamic charateristcs. A thirdgeneration nuclear power plant was selected as the research object, the influence of thehole on the wall was considered. With finite element software ABAQUS, two finteelement models were built,among which one is with a hole on the wall,the other iswithout a hole. Then, frequencies and modal shapes were obtained through modalanalysis as a way to study the influence of the hole on the structure dynamiccharacteristics. The effective mass coefficients of the first100orders of structuremodals were analyzed, and it was found that the effective mass coefficient of first22orders of modal is greater than0.9and can well meet the precondition formode-superposition response spectrum method.2. The response spectra analysis of inner containment. With the effective masscoefficientsobtained from the modal analysis, the number of orders of modal requiredfor the mode-superposition response spectrum method.was decided,then the designspectra of nuclear buildings both from <code for seismic design of nuclear powerplant/（GB50267-97）> and American regulatory guide RG1.60were input into the finiteelement analysis to do the response spectra analysis.The structure displacementresponse and stress response was gained. The influence of the hole on the shell wasstudied.,through the comparison between the response spectra analysis on the twomodels, one with a hole,the other without the hole. By comparing the difference of theseismic response resultswhen the models were subject to both design spectra, thedifference of design spectra between American code and Chinese code was learned.3. Determination of the mechanical model of inner containment building. With theformer dynamic characteristics analysis and response spectra analysis, different ordersof modal were combined, and further spectra response analysis was made. Thesimplified mechanical model was determined as cantilever bar with both bending andshear deformationand a concentrated mass point on its end. The mass of the dome was calculated.4. Study on the practical simplified analysis method based on concentrated massmethod. First of all the mechanical model was built through former research, theequivalent stiffness of cantilever bar was calculated,then the concentrated mass methodwas introduced; the equivalent mass on the end of the cantilever bar was calculated.Withthe equivalent stiffness and equivalent mass the structure natural frequency,themethod of calculating the structure fundamental frequency was formulated, also withbasic frequency、equivalent mass、equivalent stiffness，it is easy to do the responsespectra analysis. The basic procedure for this method was given in the end.5. Study on the practical simplified analysis method based on Rayleigh method.The Rayleigh method was introduced,after the determination of simplified mechanicalmodel. Considered that the maximum system kinetic energy is equal to the maximumsystem potential energy, the mechanical model of Rayleigh was a cantilever bar withdistributed mass and a concentrated mass on its end. With this mechical model, aformula for calculating the structure natural frequency was derived.The basic procedurefor this method was given in the end.6. In the end, the inner containment in this thesis and another two innercontainments from Chinese nuclear powerplant worked as three examples to verify thethis practical simplified analysis method. It turned out that the results of these practicalanalysis methods matched well with finite element analysis results which proved thatthe practical analysis methods based on Rayleigh method and concentrated massmethod are effective and accurate.