this content has been downloaded from iopscience. please ...€¦ · 6.4 containment 6-9 6.4.1 key...

20
This content has been downloaded from IOPscience. Please scroll down to see the full text. Download details: IP Address: 54.39.106.173 This content was downloaded on 12/09/2020 at 14:19 Please note that terms and conditions apply.

Upload: others

Post on 20-Jul-2020

2 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

This content has been downloaded from IOPscience. Please scroll down to see the full text.

Download details:

IP Address: 54.39.106.173

This content was downloaded on 12/09/2020 at 14:19

Please note that terms and conditions apply.

Page 2: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

Nuclear Materials Science

Page 3: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14
Page 4: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

Nuclear Materials Science

Karl WhittleSchool of Engineering, University of Liverpool, UK

IOP Publishing, Bristol, UK

Page 5: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

ª IOP Publishing Ltd 2016

All rights reserved. No part of this publication may be reproduced, stored in a retrieval systemor transmitted in any form or by any means, electronic, mechanical, photocopying, recordingor otherwise, without the prior permission of the publisher, or as expressly permitted by law orunder terms agreed with the appropriate rights organization. Multiple copying is permitted inaccordance with the terms of licences issued by the Copyright Licensing Agency, the CopyrightClearance Centre and other reproduction rights organisations.

Certain images in this publication have been obtained by the author from the Wikipedia/Wikimedia website, where they were made available under a Creative Commons licence or statedto be in the public domain. Please see individual figure captions in this publication for details. Tothe extent that the law allows, IOP Publishing disclaims any liability that any person may suffer asa result of accessing, using or forwarding the images. Any reuse rights should be checked andpermission should be sought if necessary from Wikipedia/Wikimedia and/or the copyright owner(as appropriate) before using or forwarding the images.

Permission to make use of IOP Publishing content other than as set out above may be soughtat [email protected].

Karl Whittle has asserted his right to be identified as the author of this work in accordance withsections 77 and 78 of the Copyright, Designs and Patents Act 1988.

Media content for this book is available from http://iopscience.iop.org/book/978-0-7503-1104-5/page/about-the-book.

ISBN 978-0-7503-1104-5 (ebook)ISBN 978-0-7503-1105-2 (print)ISBN 978-0-7503-1128-1 (mobi)

DOI 10.1088/978-0-7503-1104-5

Version: 20160501

IOP Expanding PhysicsISSN 2053-2563 (online)ISSN 2054-7315 (print)

British Library Cataloguing-in-Publication Data: A catalogue record for this book is availablefrom the British Library.

Published by IOP Publishing, wholly owned by The Institute of Physics, London

IOP Publishing, Temple Circus, Temple Way, Bristol, BS1 6HG, UK

US Office: IOP Publishing, Inc., 190 North Independence Mall West, Suite 601, Philadelphia,PA 19106, USA

Page 6: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

For those who may find this useful.

Page 7: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14
Page 8: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

Contents

Preface xiv

Acknowledgement xviii

Author biography xix

1 Atomic considerations 1-1

1.1 Isotopes 1-1

1.2 Nuclear stability and radioactive decay 1-2

1.3 Alpha-decay (α-decay) 1-3

1.4 Beta-decay (β-decay) 1-3

1.5 Beta+/positron emission or electron capture 1-4

1.6 Gamma emission 1-4

1.7 How do the mechanisms relate to each other? 1-4

1.8 Radioactive half-life 1-5

1.9 Decay series 1-6

1.10 Observations on isotope stability 1-7

1.11 Binding energy 1-7

1.12 Fission and fusion 1-9

1.13 Spontaneous fission 1-10

1.14 Inducing fission and chain reactions 1-11

1.15 Neutron absorption and fissile and fertile isotopes 1-11

1.16 Increasing fission yield 1-12

1.17 What are the key criteria for nuclear fission? 1-13

1.17.1 Required components 1-13

1.17.2 Desirable components 1-14

References 1-14

2 Radiation damage 2-1

2.1 Key definitions 2-2

2.1.1 Primary knock-on atom (pka) 2-2

2.1.2 Threshold displacement energy (TDE) 2-2

2.1.3 Displacements per atom (dpa) 2-2

2.2 Radiation damage 2-3

2.3 Prediction of damage—the Kinchin–Pease methodology 2-4

2.3.1 Nuclear and electronic stopping factors/powers 2-5

2.3.2 How do these powers effect the stopping of the incident particles? 2-5

vii

Page 9: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

2.3.3 The Kinchin–Pease methodology for predicting levels of damage 2-5

2.3.4 Modifications to Kinchin–Pease 2-8

2.4 Implications of damage 2-9

2.4.1 No recovery from damage 2-9

2.4.2 Full recovery from damage 2-9

2.4.3 Partial recovery from damage 2-9

2.5 Outcomes from damage 2-9

2.5.1 Basic recovery 2-9

2.5.2 Damage vs recovery 2-11

2.6 Modelling damage build-up in materials 2-12

2.6.1 Direct impact 2-13

2.6.2 Defect accumulation 2-14

2.6.3 How do they compare? 2-14

2.7 The bulk effects of damage 2-18

2.7.1 Expansion (swelling) 2-18

2.7.2 Radiation-induced segregation 2-19

2.7.3 Thermal conductivity 2-19

2.7.4 Embrittlement 2-20

2.7.5 Cracking 2-20

References 2-22

3 Nuclear fuel, part 1: fuel and cladding 3-1

3.1 What is required from fuel in a fission reactor? 3-1

3.2 Reminder of the fission process 3-1

3.3 What are the realistic types of fuel? 3-2

3.4 Uranium 3-2

3.4.1 Oxides of uranium 3-4

3.4.2 Uranium(IV) oxide (UO2) 3-4

3.4.3 Uranium (VI) oxide (UO3) 3-5

3.4.4 Uranium (IV/VI) oxides 3-6

3.4.5 Hyper/hypostoichimetric UO2±x 3-7

3.5 Plutonium 3-8

3.5.1 Oxides of plutonium 3-8

3.5.2 Plutonium (IV) oxide (PuO2) 3-9

3.5.3 Mixed oxide fuel (MOX) 3-10

3.5.4 What form is the fuel? 3-10

3.6 Fuel containment 3-11

Nuclear Materials Science

viii

Page 10: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

3.7 Zirconium-based cladding 3-14

3.7.1 Material properties of zirconium 3-14

3.7.2 Development of zirconium-based alloys for nuclear applications 3-15

3.7.3 Zirconium hydridation 3-17

3.8 Iron-based cladding 3-19

3.8.1 Advanced gas-cooled reactor cladding 3-19

3.9 How do fuel and cladding relate to each other? 3-19

References 3-20

4 Nuclear fuel, part 2: operational effects 4-1

4.1 Initial stages 4-1

4.2 Classical effects from heating 4-2

4.2.1 Why does sintering occur? 4-3

4.2.2 What are the outcomes of sintering? 4-3

4.2.3 Why do we care? 4-4

4.3 Fission products 4-4

4.3.1 Volatiles/gaseous 4-6

4.3.2 Metal particulates 4-6

4.3.3 Combined effects 4-6

4.3.4 Key impacts of fission 4-7

4.4 Initial reactor operation 4-7

4.5 Fuel cladding under operation within the core 4-10

4.5.1 Damage formation and expansion 4-11

4.5.2 Hardness and ductility 4-11

4.6 Fuel and cladding 4-11

4.6.1 Pellet–clad interaction (PCI) 4-12

4.7 Cladding corrosion 4-13

4.7.1 Corrosion mitigation and CRUD 4-14

4.7.2 Stress corrosion cracking (SCC) 4-15

4.7.3 The role of zirconium hydrides 4-16

4.7.4 Radiolysis of cooling water 4-17

References 4-18

5 Evolution of reactor technologies 5-1

5.1 Generation I—prototype reactors 5-2

5.1.1 Pressurised water reactors (PWR) 5-6

5.1.2 Gas-cooled reactor (MAGNOX) 5-7

Nuclear Materials Science

ix

Page 11: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

5.2 GenII—commercial reactors 5-9

5.2.1 Advanced gas-cooled reactors (AGR) 5-10

5.3 GenerationIII/generationIII+—evolved designs 5-11

5.3.1 Westinghouse AP and Areva EPR 5-11

5.3.2 GE-Hitachi ABWR 5-13

5.3.3 General design considerations 5-13

5.4 Molten salt reactors 5-14

5.4.1 The molten salt reactor experiment (MSRE) 5-14

5.4.2 Aircraft reactor project 5-14

5.5 Summary 5-16

5.5.1 Early reactors (GenI) 5-16

5.5.2 Commercial reactors (GenII) 5-17

5.5.3 Evolved designs (GenIII/GenIII+) 5-17

References 5-17

6 The challenges for materials in new reactor designs 6-1

6.1 Generation IV—genesis 6-1

6.2 Reactor types 6-2

6.2.1 Very high temperature reactor (VHTR) 6-2

6.2.2 Molten salt reactor (MSR) 6-2

6.2.3 Supercritical water reactor (SCWR) 6-2

6.2.4 Gas-cooled fast reactor (GFR) 6-4

6.2.5 Sodium-cooled fast reactor (SFR) 6-4

6.2.6 Lead-cooled fast reactor (LFR) 6-5

6.3 Material challenges in GenIV 6-6

6.3.1 Fuel 6-6

6.3.2 TRI-ISOtropic (TRISO) fuel 6-7

6.4 Containment 6-9

6.4.1 Key requirements for cladding 6-10

6.4.2 Liquid fuel 6-11

6.5 Radiation damage 6-14

6.6 Alternative reactor technology 6-16

6.7 Travelling wave reactor 6-16

6.8 Thorium reactors 6-17

6.8.1 Properties of thorium 6-17

6.8.2 Thorium-based fuel 6-17

6.8.3 Thorium reactor designs 6-19

Nuclear Materials Science

x

Page 12: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

6.9 Small modular reactors (SMR) 6-20

6.9.1 Proposed designs 6-20

References 6-21

7 The challenges of nuclear waste 7-1

7.1 Sources of nuclear waste 7-1

7.2 Natural sources of uranium/thorium 7-2

7.2.1 Oklo—a natural nuclear reactor 7-3

7.2.2 Development of ceramic waste forms 7-5

7.2.3 Supercalcine 7-7

7.2.4 Designing ceramic waste forms 7-7

7.2.5 Synroc 7-8

7.2.6 Criticality prevention 7-9

7.3 Long-term effects in waste forms 7-9

7.3.1 Radiation damage 7-9

7.4 Long-term behaviour of nuclear waste 7-10

7.4.1 Bulk effect of amorphisation 7-11

7.4.2 Helium bubble formation 7-12

7.5 Geological disposal of nuclear waste 7-12

7.5.1 Corrosion and nuclear waste 7-13

7.6 Ceramics and glasses—comparison 7-14

7.6.1 Ceramics 7-14

7.6.2 Glasses 7-15

7.6.3 Glass–ceramics 7-16

7.7 Transmutation 7-17

7.7.1 Implications of beta-decay 7-17

References 7-20

8 Materials and nuclear fusion 8-1

8.1 Atomic background and recap 8-1

8.2 Requirements for fusion 8-4

8.3 ITER—the International Thermonuclear Experimental Reactor 8-5

8.3.1 Design of ITER 8-5

8.4 Outcomes and challenges in fusion 8-5

8.4.1 Fuel 8-6

8.4.2 Heat 8-6

Nuclear Materials Science

xi

Page 13: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

8.4.3 Helium 8-7

8.4.4 Neutron production 8-8

8.5 Material requirements 8-8

8.5.1 First/plasma-facing wall 8-9

8.6 Radiation damage and the first wall 8-9

8.7 Sputtering 8-10

8.8 Gas bubble formation 8-12

8.8.1 Direct implantation of He from plasma 8-12

8.9 The divertor 8-13

8.10 Breeding and heat generation 8-16

8.11 Tritium breeding 8-17

8.11.1 Solid breeding 8-17

8.11.2 Liquid breeding 8-17

8.11.3 Pb–Li eutectic 8-17

8.11.4 Molten salt—FLiNaBe 8-17

8.11.5 Comparison of methods 8-18

8.12 Challenges in fission and fusion 8-20

References 8-20

9 Mistakes made and lessons learnt 9-1

9.1 Windscale—Pile 1 9-1

9.1.1 Wigner energy 9-3

9.1.2 Graphite 9-3

9.1.3 Timeline of incident 9-4

9.1.4 Aftermath 9-5

9.1.5 What caused the fire? 9-6

9.1.6 Key outcomes from the fire 9-6

9.2 Three Mile Island—Reactor 2 9-6

9.2.1 The China syndrome 9-7

9.2.2 Three Mile Island nuclear reactor complex 9-7

9.2.3 Timeline of incident 9-7

9.2.4 Aftermath 9-9

9.2.5 What caused the initial problem that led to the incident? 9-10

9.2.6 Key outcomes from the incident 9-10

9.2.7 Loss of coolant accident (LOCA) 9-10

9.3 Chernobyl—Reactor 4 9-12

9.3.1 Reaktor Bolshoy Moschonosty Kanalny (RBMK)-1000 9-12

Nuclear Materials Science

xii

Page 14: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

9.3.2 Timeline of incident 9-13

9.3.3 Aftermath 9-15

9.3.4 What caused the incident? 9-15

9.3.5 Key outcomes from the incident 9-16

9.4 Fukushima Daiichi 9-16

9.4.1 Boiling water reactor (BWR) 9-17

9.4.2 Timeline of incident 9-18

9.4.3 Aftermath 9-19

9.4.4 What caused the incident? 9-20

9.4.5 Key outcomes from the incident 9-20

9.5 How do the incidents compare? 9-20

References 9-21

Nuclear Materials Science

xiii

Page 15: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

Preface

There are 442 reactors operating in the world, generating a total of ~383 GW ofelectricity, with another 66 in various stages of construction, as shown in figure 0.1.There are various arguments both for and against nuclear power, ranging from theview that it should not be used because the waste is harmful through to the beliefthat it is necessary to generate the large amount energy needed for modern society tofunction.

Nuclear reactors are often considered to be highly complex and technical beasts,and in many ways they are. However, the principle behind a nuclear reactor isessentially the same as for most other power stations, i.e. the conversion of heat toelectricity through a turbine, predominantly a steam turbine, as shown in figure 0.2.

Fundamentally, therefore, a nuclear reactor can be compared to a steam engine,with the reactor core as the firebox, boiling water to make steam, which is then usedto drive the turbine. In essence, this the nature of a nuclear reactor, it is how we

Figure 0.1. Outline of reactors operating and under construction worldwide. Data taken from [1].

Figure 0.2. Schematic of a power station.

xiv

Page 16: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

generate the heat that is the challenge, and in the case of nuclear power this involvesthe elusive particle that is the neutron.

The magic of the neutron

The neutron is one of the core components within an atom, the other two are theproton, which is positively charged, and the electron, which is negatively charged.The neutron itself comprises two down quarks (fundamental sub-atomic particles)and one up quark, similar to a proton, which comprises one up and two downquarks, as shown in figure 0.3.

Neutrons have multiple properties, for example they are neutral in charge, butcan be influenced by a magnetic field. As a free entity, the neutron has a very shortlifetime, ~15 min is the average half-life, whereas the proton is generally consideredto be stable (otherwise there would be no hydrogen).

Neutrons can interact with matter in multiple ways, with there being two maintypes of interaction, scattering and absorption. These two then break down intoanother two, giving rise to four principal types of interaction—elastic, inelastic,absorption and fission (a schematic is shown in figure 0.4)—and within each of theseclassifications there are sub-areas. For example, absorption can involve a trans-mutation from one isotope to another, e.g. 135Xe to 136Xe, or work through what is

Figure 0.3. Comparison of the quark states in neutrons and protons.

Figure 0.4. The four main types of interaction between neutrons and matter.

Nuclear Materials Science

xv

Page 17: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

described as a transfer reaction, where one neutron is absorbed, giving rise to therelease of two neutrons, which is described as an (n,2n) reaction, e.g. 206Pb to 205Pb.

+ →Xe n Xe. (0.1)13554

10

13654

+ → +Pb n Pb 2 n. (0.2)20682

10

20582

10

Whilst there are four main types of interaction, the two of most interest arecapture and fission, which are key to the choice of materials. The scatteringinteractions are important, but for the purpose of energy generation, the transportof neutrons is key and, as will be explained through the book, it is one the keycriteria for a nuclear reactor.

As can be seen in figure 0.5, when neutrons pass through matter, if the absorptionof the material is too high neutrons will not transfer through, and get to where theycan induced fission, or in the case of fusion transmutation.

While we will discuss how neutron absorption affects the materials chosenwithin a reactor in more depth in later chapters, we can use a simple example tohighlight the impact absorption has on the thickness of materials. How thickwould a sheet of iron (Fe) need to be to have the same neutron absorption aszirconium (Zr)?

Table 0.1. Absorption data for natural Zr and Fe [2].

Element Neutron absorption (barns)

Zr 0.185Fe 2.56

Figure 0.5. Animation of grain growth in impurity free copper plycrystal.

Nuclear Materials Science

xvi

Page 18: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

This can be estimated simply by taking a ratio of the absorption of Zr to Fe(table 0.1), so in this case the new thickness would be:

= = × = μZrFe

0.1852.56

0.072 100 7.2 m. (0.3)

So, as can be seen, having low neutron absorption plays a significant role in thematerials chosen within a nuclear reactor, which has led to innovations in the pastand means challenges for the future.

This book examines the key challenges that have arisen, discusses the basis for theirimpact and how the problems can be overcome, and highlights future opportunities.However, if one were to describe the main challenge in nuclear materials as succinctlyas possible, the key phrase would be: neutrons are precious, do not waste them.

References[1] IAEA Power Reactor Information System[2] Chadwick M B et al 2006 ENDF/B-VII.0: next generation evaluated nuclear data library for

nuclear science and technology Nuclear Data Sheets 107 2931–3060Chadwick M B et al 2011 ENDF/B-VII.1 nuclear data for science and technology: cross sections,covariances, fission product yields and decay data Nuclear Data Sheets 112 2887–996

Nuclear Materials Science

xvii

Page 19: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

Acknowledgement

I would like to thank everybody who helped and assisted during the writing, whoanswered my questions, who read through chapters and who listened to me goingthrough ideas, your help was very much appreciated and welcome. In particularthanks goes to the people at IOP, who helped greatly during the writing, andprovided advice when I came across a problem I could not easily solve.

xviii

Page 20: This content has been downloaded from IOPscience. Please ...€¦ · 6.4 Containment 6-9 6.4.1 Key requirements for cladding 6-10 6.4.2 Liquid fuel 6-11 6.5 Radiation damage 6-14

Author biography

Karl Whittle

Karl received obtained his undergraduate degree at the Universityof Kent, a masters from the University of Aberdeen, and PhD fromthe Open University. After completing his PhD he undertookpostdoctoral appointments at the Universities of Bristol, Cambridgeand Sheffield, researching into amorphous materials, and nuclearwaste options. He then moved to the Australia Nuclear Science andTechnology Organisation (ANSTO), where he led research into the

effects on materials of radiation damage. In 2012 he moved back the UK as SeniorLecturer in Nuclear Materials at the University of Sheffield, and in 2015 he movedto the University of Liverpool as the Chair in Nuclear Engineering. Over the yearshe has developed research linkages across the world, with active collaborations inthe US, India, Australia and South Korea.

xix