Power Plant Building Research Articles

Earthquake response analysis of nuclear power plant buildings with soil–structural interaction

This paper gives the results of earthquake response analysis of nuclear power plant buildings in accordance with the methodology of seismic margin assessment and generic implementation procedure. Earthquake resistance of all the important buildings was considered taking a dynamic effect on soil–structures interaction (SSI) into account. The stiffness and damping values of simple soil model were compared. Limits of seismic resistance of buildings are expressed by high confidence low probability of failure. Impact contact between two structures is modeled by gap elements during the transient. The results of dynamic transient analysis on NISA and ANSYS are compared.

Construction materials for reactor buildings for decommissioning and recycling

A conceptual fluid–steel structure was studied to investigate the seismic characteristics of its use in the reactor building of nuclear power plants. The results of the earthquake response analysis of the conceptual fluid–steel structure showed that the structure had the same seismic safety ability as conventional reactor buildings. Applying the fluid–steel structure to a rector building, results in the following advantages: more elastic and light weight building materials, reducing the decommissioning wastes; the ability to recycle the structure materials because the fluid in the steel structure can be discharged the steel can be reused easily; the fluid in the steel structure has the possibility of reducing the seismic response of the structure by the sloshing damper effect. Further study is encouraged by this results.

Models test on dynamic structure–structure interaction of nuclear power plant buildings

A reactor building of an NPP (nuclear power plant) is generally constructed closely adjacent to a turbine building and other buildings such as the auxiliary building, and in increasing numbers of NPPs, multiple plants are being planned and constructed closely on a single site. In these situations, adjacent buildings are considered to influence each other through the soil during earthquakes and to exhibit dynamic behaviour different from that of separate buildings, because those buildings in NPP are generally heavy and massive. The dynamic interaction between buildings during earthquake through the soil is termed here as ‘dynamic cross interaction (DCI)’. In order to comprehend DCI appropriately, forced vibration tests and earthquake observation are needed using closely constructed building models. Standing on this background, Nuclear Power Engineering Corporation (NUPEC) had planned the project to investigate the DCI effect in 1993 after the preceding SSI (soil–structure interaction) investigation project, ‘Model Tests on Embedment Effect of Reactor Building’. The project consists of field and laboratory tests. The field test is being carried out using three different building construction conditions, e.g. a single reactor building to be used for the comparison purposes as for a reference, two same reactor buildings used to evaluate pure DCI effects, and two different buildings, reactor and turbine building models to evaluate DCI effects under the actual plant conditions. Forced vibration tests and earthquake observations are planned in the field test. The laboratory test is planned to evaluate basic characteristics of the DCI effects using simple soil model made of silicon rubber and structure models made of aluminum. In this test, forced vibration tests and shaking table tests are planned. The project was started in April 1994 and will be completed in March 2002. This paper describes an outline and the summary of the current status of this project.

大スパン長大構造の火力発電所建屋の振動特性

To obtain the vibration characteristics of a thermal power plant building with wide-span and long-length, we conducted forced vibration tests, numerical analyses correspond to these tests and seismic observation. From these studies, we obtain useful information regarding the vibration characteristics of such structural plant building mentioned above. Moreover, these results show that it is important to consider the stiffness of secondary members in case of small vibration.

Study on a concrete filled structure for nuclear power plants

The feasibility of a new structural system for nuclear power plant buildings utilizing concrete filled steel structures, termed `SC structural system' was studied. SC wall test specimens (1/5 scale) were manufactured and compressive loading tests were carried out to determine how to prevent buckling. Also, bending shear tests were performed using H-section wall specimens to determine the shear and bending characteristics of SC walls. This paper presents an outline of the feasibility study, and the various structural properties resulting from the experiments.

In Memoriam: James P. Corbett (1909-1998)

There is no limit to the complications you can introduce, if you work at it. But there is a very definite limit to the simplicity you can achieve, even if you devote a lifetime to it. Jim Corbett so admonished the assembled digital mapping researchers and developers considering yet one more complicated innovation at the Harvard Labs for Computer Graphics symposium in 1977. Jim did indeed devote a lifetime to building a simple and solid foundation for each of his endeavors, including most notably for us, digital mapping. Jim was also fond of saying, usually out of frustration with inadequate attention to his instruction: Knowing everything is the greatest impediment to learning anything. Despite his admonition against knowing everything, Jim tried to know everything. He was a student at the Art Students League in New York--Jim's paintings adorn living room walls. He left that study to join the Navy in World War II and became Chief Engineer on an aircraft carrier. Jim made a point of knowing everything about the ship, replacing all the official drawings with correct, up-to-date versions he made based on his own inspection. He played the piano and studied music theory. Jim was a superb cook; he made his own butter from fresh cream because he found commercial butter to be rancid. He always had a cat or two in his life, even on board of an aircraft carrier. Jim had a broad and intuitive grasp of mathematics. He knew the classics and applied that knowledge to current affairs. It was impossible to find a subject with which Jim was unfamiliar. His post-war career started with research at the University of Chicago and Sarnoff's lab at RCA for military applications. The research later involved diverse engineering projects, such as designing and building power plants, electronics, and data collection methods. Jim was an applied mathematician when I met him at the US Census Bureau in 1970. He created the foundation for the digital map industry two years earlier in response to the Bureau's need to control the error rate in geographic coding. Jim's scholarship and relentless quest for simplicity led him to algebraic topology as the basis for digital coding and editing of maps, originally called Dual Incidence Matrix Encoding (DIME) and later Dual Independent Map Encoding. His pioneering led everyone else there too. Now people insist that digital map systems be topological, without really knowing what that means. To be sure, others contributed to that same foundation, but none achieved the simplicity and none approached the matter with the scholarly rigor that Jim Corbett routinely applied. Scholarship is a scarce commodity even (or especially as Jim would have said) in universities. At least daily, Jim would excoriate the academic programmers, software engineers, computers scientists, developers--whatever they were calling themselves at that point for trying to reinvent mathematics, in other words, for trying to develop systems without first understanding the fundamentals of the underlying subject. …

Integration of biomass gasification and evaporative gas turbine cycles

The use of biomass for power and heat production is a growing business with vast possibilities. To make it profitable, it is necessary to design and build power plants with a low capital cost, a high degree of efficiency, even in the case of small ones, and little impact on the environment. Integration of the evaporative gas turbine cycle (EvGT) with gasification of biomass is an interesting technology that may be able to meet these demands in the future. In this paper the feasibility of integrating drying and gasification of biomass with the EvGT has been examined. Different power plant systems for cogeneration have been designed and evaluated. The systems are a combination of either atmospheric or pressurised gasification of biomass, integrated with either a steam dryer or one driven by flue gases and an EvGT. This study shows that it is thermodynamically feasible to integrate the gasification of biomass with an EvGT cycle. The systems show an electric efficiency of between 38 and 45% (LHV) and 50% moisture in fuel (initially). The total efficiency for the modelled systems ranges from 84 to 92% when the power plants are used for cogeneration.

Issues in predicting community noise for power plants

The normal method of predicting community noise levels involves first computing sound power levels from near-field sound-pressure levels and then assuming that the noise radiates from one or several point sources. This approach makes several major leaps of faith. Some of these leaps of faith or issues in predicting community noise levels for power plants are identified. The issues include validity of near-field sound-pressure levels, accuracy of sound power levels computed, radiation from large sources, transmission through building walls, and screening and reflection of noise by power plant equipment and buildings. The validity of representing large sources as one or a series of point sources is reviewed. The role of atmospheric effects and the dangers inherent in typical noise prediction software is briefly reviewed. Several examples and suggestions for making more accurate predictions are given. [See NOISE-CON Proceedings for full paper.]

Experimental study of air leakage from cracks in reinforced concrete walls

Nuclear power plant buildings must be air tight even if shaken by an earthquake of the strongest level (S1 level) even after cooling materials have been released within the structure. This study was intended to research air leakage through shear cracks in walls. Tests were done on a three-dimensional one-tenth-scale specimen based on a part of a prototype boiling-water reactor nuclear power plant. During the tests, the specimen was subjected to a lateral load, simulating those caused by an earthquake. The amount of air passing through cracks in the specimen was measured at every level of lateral loading, while the load was being applied and also after it had been removed. It was found that only very small amounts of air passed through cracks. Because nuclear power plant buildings have very thick walls, the air-tightness of these buildings appears to be secure even after an accidental loss of cooling materials followed by a severe earthquake.

One Method of Optimum Design for Piping Route in CAD System.

In this paper, we consider the CAD system for piping route design in a thermal or a nuclear power plant. The shortest-path problem is a very important item in the optimum design of a piping route design and the solution of the problem will contributes to the efficient construction and the reduction in cost of the power plant. We modelled spaces around pipelines in a power plant building and took the sum of the plant piping CAD model by adding the space model to the previous CAD model. We solved the shortest-path problem for a pipeline by applying a power multiplication method to the space model. The optimum design system in this paper offers various kinds of information for a piping route, for example, the shortest and 2nd shortest path, to the designer and he can make a final decision on the optimum route later.

Role of modelling in second-moment reliability evaluation for seismic safety of reactor buildings

Evaluation of second-moment reliability indices for seismic safety assessment requires appropriate modelling. The advantage of a simplified approach such as second-moment reliability based on a log-normal distribution postulation is the transparency of each process of the evaluation. However, the models assumed in the evaluation process have to be reasonably accurate and physically meaningful. Simplified models for seismic hazard, spectral characteristics of input motions, inelastic response behaviour and resistance evaluation are introduced and their appropriateness for the seismic safety evaluation of a nuclear power plant building, often taken as a typical important structure, is discussed.

Capacity utilization and new source bias: Evidence from the US electric power industry

While prior research has shown that new source bias has increased construction costs and delayed the building of new electric power plants, this research explores the empirical question of whether increased operating costs caused by new source bias are larger than the cost savings of newer technology. If new sources do have higher operating costs, an incentive exists to utilize order plants more intensively. Statistical evidence of these differing utilization rates is found.

An expert system for finding fragility curves of building structural systems at the preliminary design stage

Abstract This research developed an expert system for determining seismic fragility curves of structural systems in a nuclear power plant or conventional building at the preliminary design stage. The resulting system simulates the performance of human experts in identifying the potential failure modes and their likelihood for a structure of interest. Induction technique is used for knowledge acquisition. The characteristics of structural systems are described by their attributes and their values.

Model scale testing of outdoor noise propagation from a power plant

A proposed cogenerating power plant of 70-MW capacity is to be located in an urban setting and will be subject to stringent environmental noise emission criteria. A four-cell forced draft cooling tower is included in the plant design. Computer modeling of cooling tower noise propagation to affected neighboring residences involved significant uncertainties due to the complex shapes of power plant building elements and existing surrounding buildings. Without a finished facility in which to perform full-scale field tests, the next best thing is a scale model test. This paper will discuss the specifics of the 1/20th scale test setup, materials, selection, instrumentation, test execution, some problems and some lessons learned. The results of the test will be given in terms of the differences in octave band sound-pressure levels between an unobstructed free-field value and the modeled in situ value, at several receptor positions. The test enabled the specification of more precise sound attenuating elements for the cooling tower fans and inlets in order to comply with the governing regulations.

Equivalent loading due to airplaine impact taking into account the non-linearities of impacted reinforced concrete buildings

The airplane impact loading condition applied to a nuclear power plant building usually leads to very large excitations locally around the impact point and in the overall structure. This excitation is also characterized by a wide frequency content (up to 100 Hz). The state of the art of assessing the effect of an airplane impact was to apply a widely recognized rigid load function (RLF) impact force determined with Riera's Method to a linear elastic structure model and to perform calculations in order to obtain time histories and acceleration spectra. Because the real response of the building is not only governed by the elastic behaviour but also by the non-linear behaviour of the cracked and damaged concrete around the impact point the results obtained by this procedure are very conservative for the main part of the structure. The object of the paper is to present a numerical method of determining the dynamic response at characteristic points of the building taking into account the non-linear behaviour of locally impacted cracked damaged concrete. The method is based on the determination of a verified load function (VLF) which, applied to a linear elastic model of the structure, leads to the same response of the building (far from the impact point) as that due to the RLF impact force applied to a more realistic non-linear model of the reinforced concrete building. The practical advantage of using this procedure is that it avoids long and costly non-linear time integration of a full structural model. In order to obtain the VLF one only performs non-linear explicit calculations locally which include the main physical phenomenon occurring in an impacted reinforced concrete structure.

In the years 1981 and 1982 samples of soil and plants from the localities of future nuclear power plant buildings were investigated on transfer-coefficients in the soil-plant system. The concentration factors vary depending on plant species and type of soil. The concentration factors are higher in pasture plants, where the overground part of the was analysed, than in plants, where the analysed part of the plant is important for human consumption. The concentration factor for strontium depends on soil type, exchange capacity and the content of exchangable calcium in the soil.

Recursive Covariance of Structural Responses

This paper describes an effective method of obtaining covariance responses in recursive form for a multi‐degree‐of‐freedom linear structural system subjected to nonstationary random excitations. The earthquake excitations are expressed as a multiply‐correlated nonstationary autoregressive process model. By utilizing white noise characteristics of the AR model, this covariance response matrix equation is derived from state space matrix equation with mixed excitations and response components. Then, a torsional vibration model, subjected to two horizontal components of earthquake excitation, is analyzed. A BWR type nuclear power plant building is used as an example to show how recursive covariances are applied to evaluate statistical values of nonstationary maximum responses.

Recent tendency of the practice of soil-structure interaction design analysis in Japan and its theoretical background

Many methods of soil-structure interaction analysis for design calculations of nuclear power plants are available. The validity of methods has often been examined by their application to simulation analysis of shaker tests or seismic observations of nuclear power plant buildings, and forced vibration tests of large-scale foundation blocks. In this paper, such simulation analyses performed in Japan are reviewed and discussed for their practical applications.

Modeling of shear wall buildings

Many nuclear power plant buildings, for example, the auxiliary building, have reinforced concrete shear walls as the primary lateral load resisting system. Typically, these walls have low height to length ratio, often less than unity. Such walls exhibit marked shear lag phenomenon which would affect their bending stiffness and the overall stress distribution in the building. The deformation and the stress distribution in walls have been studied which is applicable to both the short and the tall buildings. The behavior of the wall is divided into two parts: the symmetric flange action and the antisymmetric web action. The latter has two parts: the web shear and the web bending. Appropriate stiffness equations have been derived for all the three actions. These actions can be synthesized to solve any nonlineal cross-section. Two specific problems that of lateral and torisonal loadings of a rectangular box have been studied. It is found that in short buildings shear lag plays a very important role. Any beam type formulation which either ignores shear lag or includes it in an idealized form is likely to lead to erroneous results. On the other hand a rigidity type approach with some modifications to the standard procedures would yield nearly accurate answers.

A laboratory model of wake-affected stack's emissions

The high demand for electric energy during winter months, which coincides with the most critical conditions from the point of view of atmospheric pollution, makes it necessary to exploit at their maximum capacity even the oldest and smallest power plants, where dispersion is usually inefficient and greatly influenced by the aerodynamic wake of the buildings. In this paper the results of a series of hydrodynamic simulations, concerning the emissions of two 70 MW units of an electric power plant are presented. It was, in fact, necessary to decide whether a certain height-increase of the stacks, within the limits imposed by the building structures, would be sufficient to reduce the elevated ground-level concentrations found in some critical wind conditions, or if new stacks, external to the power plant buildings, would be needed.