[en] In order to perform the dynamic analysis of various structural components of the HFBR reactor building at Brookhaven National Laboratory (BNL) subjected to seismic disturbances, it is necessary to obtain the floor response spectra of the primary structure. The mathematical model includes the four floor levels of the internal structure, the dome, and soil spring effects. The standard time history analysis is adopted to obtain the response spectrum for each floor of the internal structure. This report summarizes the results both in tabular and graphical form for various damping values

[en] A three-dimensional dynamic code has been developed to determine the nonlinear response of an HTGR core. The HTGR core consists of several thousands of hexagonal core blocks. These are arranged inlayers stacked together. Each layer contains many core blocks surrounded on their outer periphery by reflector blocks. The entire assembly is contained within a prestressed concrete reactor vessel. Gaps exist between adjacent blocks in any horizontal plane. Each core block in a given layer is connected to the blocks directly above and below it via three dowell pins. The present analystical study is directed towards an invesstigation of the nonlinear response of the reactor core blocks in the event of a seismic occurrence. The computer code is developed for a specific mathemtical model which represents a vertical arrangement of layers of blocks. This comprises a block module of core elements which would be obtained by cutting a cylindrical portion consisting of seven fuel blocks per layer. It is anticipated that a number of such modules properly arranged could represent the entire core. Hence, the predicted response of this module would exhibit the response characteristics of the core

[en] This paper discusses the effects of different acceptable time histories that have been applied to a linear and a nonlinear system. The time histories have been obtained from a spectral description of an earthquake event. The nonlinear system is taken as a linear one to which a cubic hardening term has been added

[en] Structures for nuclear power plant facilities etc., must be designed to resist safely and effectively all types of load combinations that may be expected during their lifetime. The basic problem involves the combination of two or more responses caused by the application of concurrent dynamic loads with random time lag. The probabilistic outcome of the combination results is represented by a cumulative distribution function (CDF), obtained by using a Monte Carlo simulation procedure. This is a report detailing the finding of four specific items related to the problem of combinations of dynamic responses. These include: (a) a parametric study of combination characteristics, (b) a generic study of the methods and criteria needed for appropriate combinations in piping components, (c) a study of the validity, adequacy, limitations and applicability of the two criteria for response combinations given in the General Electric (GE) Report (NEDO-24010-2) entitled 'Basis of Criteria for Combination of Earthquake and Other Transient Responses by the Square Root of the Sum of the Square Method', (The Kennedy-Newmark Criteria), and (d) an evaluation of Mark II response data supplied by GE under this work. A comparison of GE and BNL procedures for generating CDF curves was also made

[en] One of the primary factors in determining the structural integrity and consequently the safety of a High Temperature Gas-Cooled Reactor (HTGR) is the dynamic response of the core when subjected to a seismic excitation. The HTGR core under consideration consists of several thousands of hexagonal elements arranged in vertical stacks containing about eight elements per stack. There are clearance gaps between adjacent elements, which can change substantially due to radiation effects produced during their active lifetime. Surrounding the outer periphery of the core are reflector blocks and restraining spring-pack arrangements which bear against the reactor vessel structure (PCRV). Earthquake input motions to this type of core arrangement will result in multiple impacts between adjacent elements as well as between the reflector blocks and the restraining spring packs. The highly complex nonlinear response associated with the multiple collisions across the clearance gaps and with the spring packs is the subject matter of this paper. Of particular importance is the ability to analyze a complex nonlinear system with gaps by employing a model with a reduced number of masses. This is necessary in order to obtain solutions in a time-frame and at a cost which is not too expensive. In addition the effect of variations in total clearance as well as the initial distribution of clearances between adjacent elements is of primary concern. Both of these aspects of the problem are treated in the present analysis. Finally, by constraining the motion of the reflector blocks, a more realistic description of the dynamic response of the multi-element HTGR core is obtained

No abstract available

[en] The occurrence of PWR steam generator tube cracking, denting, and wastage has been reported in the recent literature. As indicated by its title, this paper concerns itself with the inelastic structural response of the tubes that result from various assumed monotonic as well as cyclic loading conditions, which ultimately could lead to the tube failure

[en] A three-dimensional dynamic code has been developed to determine the nonlinear response of an HTGR core. The HTGR core consists of several thousands of hexagonal core blocks. These are arranged in layers stacked together. Each layer contains many core blocks surrounded on their outer periphery by reflector blocks. The entire assembly is contained within a prestressed concrete reactor vessel. Gaps exist between adjacent blocks in any horizontal plane. Each core block in a given layer is connected to the blocks directly above and below it via three dowell pins. The present analytical study is directed towards an investigation of the nonlinear response of the reactor core blocks in the event of a seismic occurrence. The computer code is developed for a specific mathematical model which represents a vertical arrangement of layers of blocks. This comprises a 'block module' of core elements which would be obtained by cutting a cylindrical portion consisting of seven fuel blocks per layer. It is anticipated that a number of such modules properly arranged could represent the entire core. Hence, the predicted response of this module would exhibit the response characteristics of the core. (orig.)

[en] This paper discusses the effects of different acceptable time histories that have been applied to a linear and a nonlinear system. The time histories have been obtained from a spectral description of an earthquake event. The nonlinear system is taken as a linear one to which a cubic hardening term has been added. (orig.)