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- Herausgeber: Wiley-VCH
- Kategorie: Wissenschaft und neue Technologien
- Serie: Beton-Kalender Series
- Sprache: Englisch
Despite all the efforts being put into expanding renewable energy sources, large-scale power stations will be essential as part of a reliable energy supply strategy for a longer period. Given that they are low on CO2 emissions, many countries are moving into or expanding nuclear energy to cover their baseload supply. Building structures required for nuclear plants whose protective function means they are classified as safety-related, have to meet particular construction requirements more stringent than those involved in conventional construction. This book gives a comprehensive overview from approval aspects given by nuclear and construction law, with special attention to the interface between plant and construction engineering, to a building structure classification. All life cycle phases are considered, with the primary focus on execution. Accidental actions on structures, the safety concept and design and fastening systems are exposed to a particular treatment. Selected chapters from the German concrete yearbook are now being published in the new English "Beton-Kalender Series" for the benefit of an international audience. Since it was founded in 1906, the Ernst & Sohn "Beton-Kalender" has been supporting developments in reinforced and prestressed concrete. The aim was to publish a yearbook to reflect progress in "ferro-concrete" structures until - as the book's first editor, Fritz von Emperger (1862-1942), expressed it - the "tempestuous development" in this form of construction came to an end. However, the "Beton-Kalender" quickly became the chosen work of reference for civil and structural engineers, and apart from the years 1945-1950 has been published annually ever since.
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Seitenzahl: 196
Veröffentlichungsjahr: 2013
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Contents
Cover
Series Page
Title Page
Copyright
Editorial
Preface
Chapter 1: Introduction
1.1 The Demand for Energy
1.2 Electricity Generation
1.3 Importance of Nuclear Energy
Chapter 2: Nuclear Energy
2.1 Generating Electricity by Nuclear Power Plants
2.2 Nuclear Fission
2.3 Radioactivity
2.4 Reactor Designs
2.5 Safety Philosophy
Chapter 3: Approval Aspects
3.1 Atomic Energy and Construction Law
3.2 Interface Between Plant and Structural Engineering
3.3 Periodical Safety Reviews
3.4 Planning and Design Requirements
Chapter 4: Building Structures for Nuclear Plants
4.1 General Notes
4.2 Nuclear Power Plants
4.3 Disposal Structures
4.4 Building Execution
4.5 Dismantling
Chapter 5: Extraordinary Actions Involved When Designing Nuclear Installations
5.1 Overview
5.2 Internal Factors
5.3 External Actions
Chapter 6: Safety Concept and Design
6.1 Underlying Standards
6.2 Partial Safety Concept
6.3 Design Instructions for Concrete, Reinforced and Pre-Stressed Concrete Structures
6.4 Design Instructions for Steel Components
6.5 Particularities of Containment Design
Chapter 7: Fastening Systems
7.1 Fastening Types
7.2 Fastening with Headed Studs
7.3 Fastenings with Metallic Anchors
7.4 Corrosion Protection
7.5 Fire Resistance
Chapter 8: Waterproofing of Structures
8.1 Purposes on Waterproofing Structures
8.2 Requirements of Waterproofing Structures
8.3 Black Tank
8.4 White Tank
8.5 Waterproofing Concept Using the Example of the OL3 Nuclear Power Plant
Chapter 9: Ageing and Life Cycle Management
9.1 Overview
9.2 Ageing Management of Buildings
9.3 Ageing Mechanisms in Building Materials
9.4 Implementation and Documentationa
References
Index
All books published by Ernst & Sohn are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate.
Library of Congress Card No.: applied for
British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library.
Bibliographic information published by the Deutsche Nationalbibliothek
The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at <dnb.d-nb.de>.
© 2013 Wilhelm Ernst & Sohn, Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Rotherstr. 21, 10245 Berlin, Germany
All rights reserved (including those of translation into other languages). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.
Print ISBN: 978-3-433-03042-4
ePDF ISBN: 978-3-433-60274-4
ePub ISBN: 978-3-433-60275-1
mobi ISBN: 978-3-433-60276-8
oBook ISBN: 978-3-433-60277-5
Typesetting Thomson Digital, Noida, India
Coverdesign: Hans Baltzer, Berlin, Germany
Editorial
The “Concrete Yearbook” is a very important source of information for engineers involved in design, analysis, planning and production of concrete structures. It is published on a yearly basis and offers chapters devoted to various subjects with high actuality. Any chapter gives extended information based on the latest state of the art, written by renowned experts in the areas considered. The subjects change every year and may return in later years for an updated treatment. This publication strategy guarantees, that not only the most recent knowledge is involved in the presentation of topics, but that the choice of the topics itself meets the demand of actuality as well.
For decades already the themes chosen are treated in such a way, that on the one hand the reader is informed about the backgrounds and on the other hand gets acquainted with practical experience, methods and rules to bring this knowledge into practice. For practicing engineers, this is an optimum combination. Engineering practice requires knowledge of rules and recommendations, as well as understanding of the theories or assumptions behind them, in order to find adequate solutions for the wide scope of problems of daily or special nature.
During the history of the “Concrete Yearbook” an interesting development was noted. In the early editions themes of interest were chosen on an incidental basis. Meanwhile, however, the building industry has gone through a remarkable development. Where in the past predominantly matters concerning structural safety and serviceability were in the centre of attention, nowadays an increasing awareness develops due to our responsibility with regard to society in a broader sense. This is reflected e.g. by the wish to avoid problems related to limited durability of structures. Expensive repair of structures has been, and unfortunately still is, necessary because of insufficient awareness of deterioration processes of concrete and reinforcing steel in the past. Therefore structural design should focus now on realizing structures with sufficient reliability and serviceability for a specified period of time, without substantial maintenance costs. Moreover we are confronted with a heritage of older structures that should be assessed with regard to their suitability to safely carry the often increased loads applied to them today. Here several aspects of structural engineering have to be considered in an interrelated way, like risk, functionality, serviceability, deterioration processes, strengthening techniques, monitoring, dismantlement, adaptability and recycling of structures and structural materials, and the introduction of modern high performance materials. Also the significance of sustainability is recognized. This added to the awareness that design should not focus only on individual structures and their service life, but as well on their function in a wider context, with regard to harmony with their environment, acceptance by society, the responsible use of resources, low energy consumption and economy. Moreover the construction processes should become cleaner, with less environmental nuisance and pollution.
The editors of the “Concrete Yearbook” have clearly recognized those and other trends and offer now a selection of coherent subjects which resort under a common “umbrella” of a broader societal development of high relevance. In order to be able to cope with the corresponding challenges the reader is informed about progress in technology, theoretical methods, new findings of research, new ideas on design and execution, development in production, assessment and conservation strategies. By the actual selection of topics and the way those are treated, the “Concrete Yearbook” offers a splendid opportunity to get and stay aware of the development of technical knowledge, practical experience and concepts in the field of design of concrete structures on an international level.
Prof. Dr. Ir. Dr.-Ing. h.c. Joost Walraven, TU Delft
Honorary president of the international concrete federation fib
Preface
Despite all the efforts being put into expanding renewable energy sources, large-scale power plants will be essential as part of a reliable energy supply strategy for as long as we can see. Given that nuclear power is low on CO2 emissions and has no competitors when it comes to being operated cheaply, many countries are moving into or expanding nuclear energy to cover their baseload supply. Germany will need its existing nuclear power plants to supply it with cost-effective, reliable energy for many years to come, and the financial power of German utility companies like E.ON and RWE and German design and construction knowhow is helping realise new building projects in neighbouring countries. At home, there are many challenges to be met when it comes to continuously updating existing plant. The authors are extensively involved in designing, operating and inspecting existing plant, designing newbuilds, doing retrofits and conversions and updating specific nuclear power rules.
We would like to thank Christina Busse and Björn Elsche of E.ON-Kernkraft GmbH, Hanover, Frau Jelena Trubnikova and Alexander Fischer, Stephan Fromknecht, Wolfgang Fuchs, Andreas Garg, Thomas Grünzig, Heribert Hansen, Peter Kretzschmar, Mark Kritzmann, Hamid Sadegh-Azar, Thomas Springsguth and Marco Tschötschel of HOCHTIEF Consult IKS Energy, Frankfurt am Main for their assistance in writing this work. Some text modules were supplied by Sören Müller and Martin Schäfer of the staff of the Technical University Kaiserslautern and Ralf Schliwa of BORAPA Ingenieurgesellschaft. Final editing was by Frau Tanja Volk.
Hanover
Rüdiger Meiswinkel
Frankfurt Main
Julian Meyer
Kaiserslautern
Jürgen Schnell
1
Introduction
1.1 The Demand for Energy
As the world's population grows, the demand for primary energy, and hence electrical energy, is growing massively with it. At the same time, the demand for individual electrical power is increasing, especially as the so-called emerging nations are seeing their energy demand soar as they strive to become industrialised. The International Energy Agency (IEA) estimates that businesses and private households will need around 60% more energy by 2030 than they do today. With their massive populations, China and India will account for two-thirds of the increasing demand forecast.
The result, ‘More and more people needing more and more energy’, is shown in Figure 1.1. Between 2000 and 2020, world population is set to increase from six to eight billion (33%), but the demand for energy is forecast to rise at nearly twice the rate, by around 62%. This increase will mean major challenges in terms of a sustainable energy supply, based on the three-pillar concept of balancing economics, ecology and society, as set at the world summit in Rio de Janeiro in 1992.
Fig. 1.1 Growth in global energy demand
,1.2 Electricity Generation
A number of options are available to cover this energy demand: they can basically be divided into two groups, thermal power plants and power plants running on renewable energy sources. Thermal power plants break down into oil-fired, gas-fired, lignite-fired, hard-coal-fired and nuclear power plants. Apart from hydroelectric power, the main renewable energy sources are wind power, solar energy, biomass and geothermal energy.
Different electricity production options are rated differently in environmental and economic terms, but the difference in generating power (a 1000 MW coal-fired power plant is equivalent to 200 offshore or 400 onshore wind farms, for example) makes it clear that, essentially, the only way that rising world energy demand will be met is by using powerful cogeneration plants.
As Figure 1.2 shows, even though renewable energies are set to expand enormously in the coming decades, the capacity they actually generate will only grow slightly, so that their percentage share of total electricity generated will actually fall. The forecasts by World Energy Council (WEC) and IEA also say that even after 2020, more than 70% of energy will be obtained from coal, oil and gas, and the share of nuclear power will increase considerably. As well as output, having a reliable electricity supply is also extremely important, which also shows that thermal power plants are essential. If we look at a typical day load curve as in Figure 1.3 – broken down into baseload, average load and peak load – it is clear that thermal power plants are needed for baseload particularly.
Fig. 1.2 World energy demand and coverage (WEC reference scenario)
Fig. 1.3 Energy supply load curve
1.3 Importance of Nuclear Energy
In contributing towards covering world energy demand over a forecast period up to 2050 (Figure 1.2), nuclear energy plays a key role in generating electricity, which will mean a large number of newbuild projects worldwide. As the overview in Figure 1.4 shows, as at autumn 2009, as well as the 437 nuclear power plants already in operation, another 53 new nuclear power blocks were under construction, and another 76 new blocks were planned. The new blocks currently being built or planned mostly have (electricity) outputs from 1000 to 1600 MW. (Please note: the figures given in MW below indicate electrical energy, as opposed to thermal energy, which is stated in MWth.)
Fig. 1.4 Generating energy from nuclear power [1]
Nuclear energy now provides around 15% of the electricity generated worldwide. It avoids around 2.5 bn tonnes of CO2 emissions, so it makes a major contribution towards a sustainable electricity supply which achieves the goals in terms of economics, capability and the environment to a large extent.
For Germany, which uses wind energy relatively intensively, direct comparison shows that theoretically more wind energy was installed than nuclear in 2008 (23,300 MW as against 21,497 MW), but nuclear generated much more energy than wind, at 148.8 TWh as against 40.2 TWh. In other words, nuclear energy generates nearly 50% of baseload electricity in Germany.
Just how important nuclear energy is can also be seen from how economical it is in generating electricity. Building new nuclear power plants is relatively expensive in terms of capital costs, but the fuel costs involved (uranium), including disposal, are so low that the total cost (including disposal and end stage planning) of generating electricity is around 3–4 Euro cents per kWh [2]. This means that nuclear power is not affected by volatile fuel prices and guarantees a reliable supply, as the uranium deposits that are worth extracting at today's prices will be enough for more than 200 years, are spread across the world and the countries they originate in are politically stable.
The world, and Europe in particular, has recognised how important nuclear energy is when it comes to generating electricity, as the many newbuild projects show. A number of European countries, including Finland, France and Britain, have actually been building new nuclear power plants or planning them since 2005. These newbuild projects impose different requirements on structural engineering, not just in building them, but in interim and final storage and restoration work. We will look at these tasks, with their specific safety requirements, below.
2
Nuclear Energy
2.1 Generating Electricity by Nuclear Power Plants
Basically, nuclear power plants work in the same way as coal- and gas-fired plants, converting heat to electricity. Whereas fossil-fuel-fired power plants run on energy media such as oil, lignite or hard coal, nuclear power plants use the heat given off when atomic nuclei split.
Figure 2.1 shows how a nuclear power plant works (in this case, a pressurised water reactor, cf. Section 2.4.2) and shows the whole energy conversion process. Nuclear fission inside the reactor pressure vessel generates heat, which heats water until it vaporises, turning thermal energy into latent energy in steam. This steam, which is under high pressure, then drives the turbines (converting to mechanical energy), which turn the generators connected to them, generating electrical energy, like a bicycle dynamo. Condensing the steam required to drive the turbines is done either by direct flow or seawater cooling or via a cooling system using a cooling tower.
Fig. 2.1 How a nuclear power plant works (pressurised water reactor model)
2.2 Nuclear Fission
Most elements on Earth are stable, and the structure of their atomic nuclei is constant. A few of them decompose radioactively, however: that is to say, their atomic nuclei turn into those of other elements by emitting radiation or particles.
In a nuclear reactor, or a reactor at a nuclear power plant, nuclear fission is induced deliberately and the resulting radioactive decay used. Atomic nuclei are split by bombarding them with neutrons.
The process of nuclear fission is shown in Figure 2.2. In the reactor, uranium U-235 nuclei are bombarded with neutrons, causing them to fission and emit radiation, known as ‘nuclear radiation’ (cf. Section 3). The products of decay are usually two fission products, such as krypton or barium, and two or three neutrons. The neutrons that are emitted can in turn split other atomic nuclei, setting off a chain reaction in which energy is released.
Fig. 2.2 The nuclear fission process
The fission products that arise when atomic nuclei split are unstable: they give off radioactive radiation, turning into stable end products, releasing more energy in the process. This post-decay heat keeps on being generated even after a nuclear reactor has been shut down, and requires special post-cooling systems (Figure 2.3).
Fig. 2.3 Thermal output from a reactor once it is shut down
A constant steady chain reaction needs a certain minimum mass of fissionable material, also known as the ‘critical mass’. Critical mass exists if the number of secondary fissions (second generation neutrons) is equal to the number of primary fissions (first generation neutrons).
Uranium U-235 is the only element occurring in nature that can maintain fission via a chain reaction. U-235 accounts for just 0.72% of the total mass of uranium occurring naturally, so it does not provide the critical mass required: this has to be increased, i.e. the uranium has to be enriched. This can be done using diffusion, gas centrifuges or separation nozzles.
The critical mass of U-235 required is less if the neutrons that are released when its nuclei split can be slowed down to lower, thermal speeds (moderated). This can be done using what is known as a moderator. Apart from carbon in graphite form and heavy water (deuterium oxide, or D2O), this is best done using light water, or H2O. The water molecules slow the neutrons down very effectively, thus maintaining the chain reaction; and the water absorbs the energy from nuclear fission, which heats it up considerably, making it ideal for generating electricity. When using H2O as moderator, the natural uranium has to be enriched to around 3.5% U-235.
2.3 Radioactivity
Radioactivity can be defined as when atomic nuclei of one element turn into nuclei of another element, emitting radiation or particles in the process. Radioactive processes can be divided into decays of different kinds. The most important decay and radiation processes involved with uranium ore are as follows (Figure 2.4):
Fig. 2.4 Radioactivity and shielding
What effects radiation has depends on what kind of radiation it is, what the dosage levels are over time and how sensitive the material being radiated is. Radiation absorbed by the human body is abbreviated to Rad for short (radiation absorbed dose).
At a given energy dose D, the biological effects may vary considerably, depending on the type of radiation involved: so a weighted radiation dose (equivalent dose) is used as the biologically effective dose. This equivalent dose H is expressed in sieverts (Sv), generally quoted as mSv or μSv, and is calculated from the energy dose D and an assessment factor q which reflects the characteristics of the radiation. This radiation dose over time then gives the radiation load as a dosage level. A number of natural and man-made radiation sources, with their radiation loads, are compared in Figure 2.5.
Fig. 2.5 Natural and man-made radiation sources
The radiation load from nuclear power plants is controlled by law, so the limits as stated in the radiation protection regulations must not be exceeded, even where the effects are worst. Nuclear power plants also have retention systems to prevent radioactive substances getting into the environment.
These retention systems include:
If we look at the radioactive waste from nuclear power plants more closely, we find that, once it has been used in the nuclear reactor, the high-energy nuclear fuel consists of 95% uranium, 4% fission products and 1% plutonium. This spent nuclear fuel can be reprocessed, recycling its useful component, but the current nuclear consensus in Germany has ruled out reprocessing, so spent fuel elements must be kept in intermediate storage until they are put into final storage at the nuclear power plant sites (see also Section 4.4). As well as this highly active waste, nuclear power plants also produce moderate- and low-activity waste. Putting this more clearly: a 1300 MW pressurised water reactor produces around 510 m3 of radioactive waste a year in total, of which 1% is highly active and around 92% is low-activity waste (Figure 2.6).
Fig. 2.6 Radioactive waste from a 1300 MW pressurised water reactor (approx. 510 m3 p.a.)
2.4 Reactor Designs
2.4.1 Overview
Many kinds of nuclear reactors have been developed since the discovery of uranium's nuclear decay in 1938. These can be divided into generations, in the order in which they were developed, as follows:
(Remark: At the international level, Generation III is often classed as part of Generation II, so Generation III+ is referred to as Generation III.)
Of the types of nuclear reactor that have been developed, there are only a few that can be used in commercial operation. The different types can be broken down by the following aspects:
The first basic distinction here is between thermal and fast reactors. Fast reactors are better known as fast breeders, because when they are operating they ‘breed’ more fissionable plutonium from the uranium than they use, which means that they can get around twice as much energy out of the uranium. Fast breeders have failed to establish themselves, however, for a number of reasons (political reasons in Germany).
Amongst the thermal reactors, there are a number of combinations of moderators and coolants which have been developed successfully for commercial use (Table 2.1). The two main families involved here are gas-cooled reactors (Magnox reactors), advanced gas-cooled reactors and high-temperature reactors and water reactors (light and heavy water reactors).
Table 2.1 Different types of reactor (different combinations of moderator and cooling)
The most important of these are the light water reactors, as they are also operated in Germany at present. They have proved themselves worldwide, and are the reactors of choice not least because of their safety aspects. Apart from a few exceptions, light water reactors are the only ones that have been designed and built worldwide for some years now.
2.4.2 Light Water Reactors
The water which is typically used as coolant in light water reactors can be used both in a single-circuit system or – to prevent contamination – in a multiple-circuit system via heat exchangers. Light water reactors are known as pressurised water reactors (PWRs) or boiling water reactors (BWRs), depending on whether the water in them is pressurised or boiling.
In a pressurised water reactor, the water in the reactor pressure vessels is at extremely high pressure, around 150 bar, so the water does not boil, even at the design operating temperature of 300 °C. This prevents steam bubbles forming, which would complicate the heat transfer process.
As Figure 2.7
