Main Editorial Panel D. J. Littler, BSc, PhD, ARCS, CPhys, FInstP, CEng. FIEE (Chairman) * Professor E. J. Davies, DSc, PhD, CEng, FIEE H. E. Johnson F. Kirkby, BSc, CEng, MIMechE, AMIEE P. B. Myerscough, CEng, FIMechE, FINucE W. Wright, MSc, ARCST, CEng, FIEE, FIMechE, FInstE, FBIM Volume Consulting Editor P. B. Myerscough, CEng, FIMechE, FINucE Authors Chapter 1 I. G. Crossland A. R. Pugh P. B. Myerscough K. A. Simpson J. E. M. Palmer R. E. Streatfield Chapter 2 G. S. Anderson D. W. James A. C. Ashton M. W. Jervis E. W. Beagles R. Knox V. S. Beckett J. Lobley T. C. Beswich S. F. Loveday J. R. Clark D. P. Luckhurst R. K. Cook P. N. Malcolm A. A. Deas J. I. McWilliam D. D. Dixon G. B. Moutrey T. R. Edmondson G. L. Potts W. Elliott C. R. Simons C. H. Fifield L. E. Wallhead D. S. Hiorns M.C. Whitaker K. W. Ingle N. V. Worthington Chapter 3 M. J. Bridge A. R. R. Telford R. J. Filby P. Webber J. Hugh M.J. Whitehead M.W.Jervis Chapter 4 M.J. Arnold A. R. Myatt I. Dougall G. A. Niçois A. R. Gregory H. C. Orchard T. P. Haire A. Short D. W. Hughes M.J. Webb J. Mathieson Series Production Managing Editor P. M. Reynolds Production Editor H. E. Johnson Resources and T. A. Dolling Co-ordination J. R. Jackson MODERN POWER STATION PRACTICE Third Edition Incorporating Modern Power System Practice British Electricity International, London volume J Nuclear Power Generation PERGAMON PRESS OXFORD · NEW YORK · SEOUL · TOKYO U.K. Pergamon Press pic, Headington Hill Hall, Oxford 0X3 OBW, England U.S.A. Pergamon Press, Inc., 395 Saw Mill River Road, Elmsford, New York 10523, U.S.A. KOREA Pergamon Press Korea, KPO Box 315, Seoul 110-603 Korea JAPAN Pergamon Press Japan, Tsunashima Building Annex 3-20-12 Yushima, Bunkyo-ku, Tokyo 113, Japan Copyright © 1992 British Electricity International Ltd All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise, without permission in writing from the copy­ right holder. First edition 1963 Second edition 1971 Third edition 1992 Library of Congress Cataloging in Publication Data Modern power station practice: incorporating modern power system practice/British Electricity International.— 3rd ed. p. cm. Includes index. 1. Electric power-plants. I. British Electricity Inter­ national. TK1191.M49 1990 62.31'21 — dc20 90-43748 British Library Cataloguing in Publication Data British Electricity International Modern power station practice.—3rd. ed. 1. Electric power-plants. Design and construction I. Title II. Central Electricity Generating Board 621.3121. ISBN 0-08-040510-X (12 Volume Set) ISBN 0-08-040519-3 (Volume J) Printed in the Republic of Singapore by Singapore National Printers Ltd Colour Plates (between pp 338 and 339) FIG. 2.30 A 50 tonne road transport flask, with its lid in place, being removed from the cooling pond at Oldbury FIG. 2.33 Charge face machinery at Berkeley, showing the servicing machine on the left and the charge/discharge machine on the right FIG. 2.34 Fuelling machine at Sizewell A power station FIG. 2.35 Servicing machine at Wylfa power station FIG. 2.36 Fuelling machine at Hinkley Point A power station FIG. 2.37 Fuelling machine at Trawsfynydd power station FIG. 2.38 Fuelling machine at Oldbury power station FIG. 2.100 TRIUMPH reactor inspection cameras FIG. 2.119 Central control room at Heysham 2 FIG. 2.120 Post trip cooling mimic panel FIG. 3.46 Fuel transport flask tug/trailer unit (between pp 530 and 531) FIG. 4.6 Mark 2 magnox fuel element transport flask FIG. 4.11 Magnox reactor simulator FIG. 4.12 AGR simulator FIG. 4A Berkeley magnox power station — steel pressure vessel, commissioned 1962 FIG. 4B Bradwell magnox power station — steel pressure vessel, commissioned 1962 FIG. 4C Hinkley Point A magnox power station — steel pressure vessel, commissioned 1965 FIG. 4D Trawsfynydd magnox power station — steel pressure vessel, commissioned 1965 FIG. 4E Dungeness A magnox power station — steel pressure vessel, commissioned 1965 FIG. 4F Sizewell A magnox power station — steel pressure vessel, commissioned 1966 FIG. 4G Oldbury magnox power station — concrete pressure vessel, commissioned 1967 FIG. 4H Wylfa magnox power station — concrete pressure vessel, commissioned 1973 FIG. 4J Hinkley Point B AGR power station, commissioned 1978 FIG. 4K Dungeness B AGR power station, commissioned 1983/85 FIG. 4L Hartlepool AGR power station, commissioned 1983/84 FIG. 4M Heysham / AGR power station, commissioned 1983/84 FIG. 4N Heysham 2 AGR power station, commissioned 1988 VI Foreword G. A. W. Blackman, CBE, FEng Chairman, Central Electricity Generating Board and Chairman, British Electricity International Ltd FOR OVER THIRTY YEARS, since its formation in 1958, the Central Electricity Generating Board (CEGB) has been at the forefront of technological advances in the design, construction, operation, and maintenance of power plant and transmission systems. During this time capacity increased almost fivefold, involving the introduction of thermal and nuclear generating units of 500 MW and 660 MW, to supply one of the largest integrated power systems in the world. In fulfilling its statutory responsibility to ensure continuity of a safe and economic supply of electricity, the CEGB built up a powerful engineering and scientific capability, and accumulated a wealth of experience in the operation and maintenance of power plant and systems. With the privatisation of the CEGB this experience and capability is being carried forward by its four successor companies — National Power, PowerGen, Nuclear Electric and National Grid. At the heart of the CEGB's success has been an awareness of the need to sustain and improve the skills and knowledge of its engineering and technical staff. This was achieved through formal and on-job training, aided by a series of textbooks covering the theory and practice for the whole range of technology to be found on a modern power station. A second edition of the series, known as Modern Power Station Practice, was produced in the early 1970s, and it was sold throughout the world to provide electricity undertakings, engineers and students with an account of the CEGB's practices and hard-won experience. The edition had substantial worldwide sales and achieved recognition as the authoritative reference work on power generation. A completely revised and enlarged (third) edition has now been produced which updates the relevant information in the earlier edition together with a comprehensive account of the solutions to the many engineering and environmental challenges encountered, and which puts on record the achievements of the CEGB during its lifetime as one of the world's leading public electricity utilities. In producing this third edition, the opportunity has been taken to restructure the information in the original eight volumes to provide a more logical and detailed exposition of the technical content. The series has also been extended to include three new volumes on 'Station Commissioning', 'EHV Transmission' and 'System Operation'. Each of the eleven subject volumes had an Advisory Editor for the technical validation of the many contributions by individual authors, all of whom are recognised as authorities in their particular field of technology. All subject volumes carry their own index and a twelfth volume provides a consolidated index for the series overall. Particular attention has been paid to the production of draft material, with text refined through a number of technical and language editorial stages and complemented by a large number of high quality illustrations. The result is a high standard of presentation designed to appeal to a wide international readership. It is with much pleasure therefore that I introduce this new series, which has been attributed to British Electricity International on behalf of the CEGB and its successor companies. I have been closely associated with its production and have no doubt that it will be invaluable to engineers worldwide who are engaged in the design, construction, commissioning, operation and maintenance of modern power stations and systems. Preface The contents of this new edition of the nuclear volume of Modern Power Station Practice reflect the considerable expansion and development of nuclear power generation in the UK since the initial volume was published in 1964. During that period the AGR programme has been completed, the approval of Sizewell B launches a new generation of PWR stations and the first of the Magnox has completed its useful life. Thus the current volume presents a comprehensive picture of the design, development and operation of the majority of the nuclear station designs currently being operated throughout the world. In rewriting the volume, the original format has been completely changed to accom­ modate the now compendious technical nature of the subject with four independent but complementary chapters, Nuclear physics and basic technology; Nuclear station design; Nuclear station operation and Nuclear safety. Although each chapter is complete within itself, some overlap of technical matter between the chapters is inevitable and indeed essen­ tial, reflecting the co-operation of widely differing technical disciplines necessary to ensure the safe and economic design and operation of nuclear stations. In order to keep the size of the volume to reasonable proportions, consideration of plant and procedures which are common to both nuclear and fossil-fired stations have been omitted. For instance those aspects of once-through boilers which are not specific to AGR or PWR designs have been confined to Volume B. The presentation of such a wide-ranging review of nuclear power has been made pos­ sible only by the expertise provided by some fifty-one authors, all practising engineers and scientists of national and international reputation from the CEGB and the National Nuclear Corporation. The editing of such a wide variety of expertise has been a formidable but enjoyable task and the resulting volume represents the distillation of many years of experience in the design and operation of nuclear plant which must be unrivalled both in the UK and overseas. I should like to record my thanks to all the authors, many of them colleagues from the CEGB, for their co-operation in providing the editorial material and in meeting the production deadlines. I should also like to thank the staff at the National Training Resources Unit of the CEGB, in particular Peter Reynolds without whose hard work in the production of the illustrations, tables and references, the publication of the volume would not have been possible. P. B. MYERSCOUGH Consulting Editor — Volume J IX Contents of All Volumes Volume A — Station Planning and Design Power station siting and site layout Station design and layout Civil engineering and building works Volume B — Boilers and Ancillary Plant Furnace design, gas side characteristics and combustion equipment Boiler unit — thermal and pressure parts design Ancillary plant and fittings Dust extraction, draught systems and flue gas desulphurisation Volume C — Turbines, Generators and Associated Plant The steam turbine Turbine plant systems Feedwater heating systems Condensers, pumps and cooling water systems Hydraulic turbines The generator Volume D — Electrical Systems and Equipment Electrical system design Electrical system analysis Transformers Generator main connections Switchgear and control gear Cabling Motors Telecommunications Emergency supply equipment Mechanical plant electrical services Protection Synchronising Volume E — Chemistry and Metallurgy Chemistry Fuel and oil Corrosion: feed and boiler water Water treatment plant and cooling water systems Plant cleaning and inspection Metallurgy Introduction to metallurgy Materials behaviour Non-ferrous metals and alloys Non-metallic materials Materials selection xi Contents of All Volumes Welding processes Non-destructive testing Defect analysis and life assessment Environmental effects Volume F — Control and Instrumentation Introduction Automatic control Automation, protection and interlocks and manual controls Boiler and turbine instrumentation and actuators Electrical instruments and metering Central control rooms On-line computer systems Control and instrumentation system considerations Volume G — Station Operation and Maintenance Introduction Power plant operation Performance and operation of generators The planning and management of work Power plant maintenance Safety Plant performance and performance monitoring Volume H — Station Commissioning Introduction Principles of commissioning Common equipment and station plant commissioning Boiler pre-steam to set commissioning Turbine-generator/feedheating systems pre-steam to set commissioning Unit commissioning and post-commissioning activities Volume J — Nuclear Power Generation Nuclear physics and basic technology Nuclear power station design Nuclear power station operation Nuclear safety Volume K — EHV Transmission Transmission planning and development Transmission network design Overhead line design Cable design Switching station design and equipment Transformer and reactor design Reactive compensation plant HVDC transmission plant design Insulation co-ordination and surge protection Interference Power system protection and automatic switching Telecommunications for power system management Transmission operation and maintenance XII Contents of All Volumes Volume L — System Operation System operation in England and Wales Operational planning — demand and generation Operational planning — power system Operational procedures — philosophy, principles and outline contents Control in real time System control structure, facilities, supporting services and staffing Volume M — Index Complete contents of all volumes Cumulative index XIII C H A P T ER 1 Nuclear physics and basic technology 1 Basic concepts 5.1.2 High collision rate 1.1 Structure of the atom 5.2 Slowing down power 1.2 Structure of the nucleus 5.3 Moderating ratio 1.3 Equivalence of mass and energy 5.4 Other factors 1.3.1 Einstein's equation 5.5 Possible moderator materials 1.3.2 Unified mass unit and the electron volt 6 The four-factor formula 1.3.3 Mass defect and binding energy 6.1 Reactor design considerations 1.4 Radioactivity 1.4.1 Unstable nuclei 6.2 The neutron life cycle 1.4.2 Radioactive nuclei 6.2.1 Thermal utilisation factor T 1.4.3 Excited nuclei — gamma radiation 6.2.2 Thermal fission factor 'η' 1.4.4 Half life 6.2.3 Fast fission factor 'e' 1.5 Interaction of ionising radiation with matter 6.2.4 Resonance escape probability 'p' 1.5.1 Ionising radiations 6.3 koo = per/f 1.5.2 Alpha particles 7 The finite reactor 1.5.3 Beta particles 7.1 The effective multiplication constant, k ff 1.5.4 Gamma rays e 7.2 Non-leakage probability, PNL 1.5.5 Shielding 7.3 Maximising P|sj|_ (minimising P\J 2 Nuclear reactions 7.3.1 Reactor size 2.1 Interaction of radiation with nuclei 7.3.2 Critical size 2.2 The compound nucleus 7.3.3 Reactor shape 2.3 Neutron reactions 7.4 The diffusion theory 2.3.1 Scattering reactions 7.4.1 Neutron flux distributon 2.3.2 Absorption reactions 7.4.2 One, two and multi group theory 2.4 Cross-sections for nuclear reactions 7.4.3 Expression for PNL 2.4.1 Microscopic cross-section 7.4.4 The critical reactor 2.4.2 Macroscopic cross-section 7.4.5 The reflected reactor 2.4.3 Thermal neutrons 8 Heat transfer and fluid flow 3 Nuclear fission reaction 8.1 Introduction 3.1 The fission event 8.2 Laws of heat transfer by conduction 3.2 Fissionable, fissile and fertile materials 8.3 Temperature distribution across a reactor fuel rod 3.2.1 Fissionable materials 8.4 Heat transfer from a solid to a fluid 3.2.2 Fissile materials 8.5 Correlation of factors affecting heat transfer 3.2.3 Fertile materials 8.6 Temperature drop across a fuel channel 3.2.4 Natural uranium 8.7 Temperature variations along a fuel channel 3.3 Properties of the fission event 8.8 Heat distribution in a cylindrical reactor 3.3.1 Fission fragment yield 8.9 Heat absorbed by coolant in a fuel channel 3.3.2 Number of neutrons emitted per fission (v) 8.10 Temperature distribution across the core 3.3.3 Energy of the neutrons 8.11 Fluid flow 3.3.4 Prompt and delayed neutrons 9 Nuclear power reactors 3.3.5 Energy release per fission 3.3.6 Decay heat 9.1 Introduction 3.3.7 Summary of the fission process 9.2 Light water reactor (LWR) 9.2.1 Pressurised water reactor (PWR) 4 Nuclear chain reaction 9.2.2 Boiling water reactor (BWR) 4.1 The chain reaction 9.3 Heavy water reactor (HWR) 4.2 The multiplication constant k 9.3.1 Candu (PHWR) 4.3 Chain reaction in natural uranium — fast neutrons 9.3.2 Steam generating heavy water reactor (SGHWR) 4.3.1 Fission 9.4 Graphite moderated reactor 4.3.2 Capture 9.4.1 Magnox reactor 4.3.3 Scatter 9.4.2 Advanced gas cooled reactor (AGR) 4.3.4 koo for natural uranium and fast neutrons 9.5 Fast breeder reactor (FBR) 4.4 To achieve k<x>>1 4.4.1 Fuel enrichment 10 Properties of reactor materials 4.4.2 Neutron moderation 10.1 Fuels 10.1.1 Introduction 5 The moderator 10.1.2 Uranium metal fuels 5.1 Requirements of a good moderator 10.1.3 Uranium oxide fuels 5.1.1 High energy transfer per collision 10.2 Nuclear cladding