Nuclear power plants provide around 20% of the total electrical supply in the United States and roughly around the same level across the world, help­ing to reduce harmful greenhouse gases (GHG). Many commercial nuclear reactors operating worldwide are of the Generation-II category and the majority of this generation is light water type; Generation-III type reac­tors are at an advanced stage of commercialization and deployment. The main reasons for downtime of the light water reactors (LWRs) currently operating are materials-related issues primarily due to material ageing and degradation. Degradation of materials is caused by the very aggres­sive environments to which the LWR structures are exposed including high neutron fluences, high temperatures along with aggressive environmental factors such as water and steam. A major objective of this book is to bring forth issues confronting the nuclear industry in terms of materials ageing and degrading with particular emphasis on mechanisms and management. This book is a compilation of chapters written by experts in the field. The book is divided into three different parts: Part I on ‘Fundamental ageing issues and degradation mechanisms’, Part II on ‘Materials ageing and deg­radation in particular light water reactor (LWR) components’ and Part III on ‘Materials management strategies for light water reactors (LWRs)’. Each of these three parts contains three chapters.

In Chapter 1, Murty and Ramaswamy present an overview of various materials issues with discussions on fundamental aspects along with per­tinent references to various materials of different LWR structures. The chapter covers briefly all the seven components (fuel, structure, moderator/ reflector, control, coolant, shields and safety systems) comprising an LWR with references that deal with more details. Corrosion and stress corrosion cracking (SCC) are the most commonly limiting factors and damaging phe­nomena that are covered in Chapter 2 by Couvant. This is an important chapter that summarizes the corrosion phenomena encountered in LWRs. Murty et al, discuss in detail the time-dependent permanent deformation known as creep in Chapter 3 , Any structure that is exposed to high tem­peratures and loads experiences creep deformation, and both the creep mechanisms and creep-life prediction methodologies are important aspects

covered here, referencing their applications to LWR structural materials such as Zr-based alloys, stainless steels and Ni-based superalloys.

Part II on Materials ageing and degradation of specific light water reac­tor components comprises three chapters commencing with Chapter 4 by Adamson and Rudling on the zirconium-based alloys that are commonly used as thin-walled tubing to clad radioactive UO2 fuel. This chapter starts with the basic crystallography of Zr leading to many degradation phenom­ena often noted in operating reactors of both PWR and BWR type such as PCI (pellet-cladding interaction), oxidation and hydriding, crud forma­tion, radiation growth and creep, grid-to-rod-fretting (GTRF), fuel rod and assembly bow. Rudling and Adamson continue the issues of Zircaloy cladding in Chapter 5 with emphasis on performance and inspection of fuel bundle components. Issues of possible degradation and ageing of various electrical cables are dealt by Hashemian in Chapter 6; it is to be noted that the various aspects covered in this chapter are usually found only in special­ized treatises.

Part III covers Materials management strategies wherein Chapter 7 by Jeong and Hwang deals with PWR management in Korea while Katona describes similar aspects for Russian VVERs in Chapter 8 . In the final chapter, Ray and Lahoda cover materials problems facing operating LWR vendors following which the needs of nuclear technology and industry are pointed out.

The uniqueness of the book lies in the fact that, while fundamental materials aspects/phenomena are dealt with initially, other content is not easily found in the technical journals on nuclear materials, especially the management strategies of LWR vendors covered in Part III. The various materials science aspects described in these articles for predicting the life of nuclear structures echo the comment made by Placid Rodriguez during his Presidential address delivered at the Golden Jubilee Celebration of the Indian Institute of Metals in 1966: To be able to predict the life of an engineer­ing component accurately, … [one needs to] take into account the synergistic effects of and interactions between a variety of damaging processes like creep, fatigue, dynamic strain ageing, environmental effect and microstructural deg­radation. The importance and significance of knowledge and background in nuclear materials are nicely summed up by Norman Hilberry, the former director of Argonne National Laboratory, who made the following state­ment way back in the 1950s: We physicists can dream up and work out all the details of power reactors based on dozens of combinations of the essentials, but it’s only a paper reactor until the metallurgist tells us whether it can be built and from what. Then only, one can figure whether there is any hope that they can produce power.

Acknowledgements are due to the efforts and continued persistence of Messrs. Steven Mathews, Sarah Hughes and Rachel Cox of Woodhead

Publishing in arranging for various authors to contribute their chapters in an appropriate time frame and in making this publication a reality.

K. Linga (KL) Murty Professor and Director of Graduate Programs Department of Nuclear Engineering North Carolina State University