R. B. ADAMSON, Zircology Plus, USA and P. RUDLING, ANT International, Sweden

DOI: 10.1533/9780857097453.2.151

Abstract: This chapter highlights the various uses and properties of zirconium alloy cladding and structural components used in nuclear power light water reactors. Specific attributes including dimensional stability, corrosion resistance, irradiation effects and mechanical properties are discussed in detail.

Key words: zirconium alloys, nuclear reactors, dimensional stability, radiation effects, mechanical properties, corrosion.

4.1 Introduction

Zirconium alloys are used as the prime structural material in light water reactors (LWRs). As such, they have to meet several requirements: low neutron absorption cross section; corrosion resistance in 280-350°C water; resistance to radiation in both mechanical behaviours and dimensional sta­bility; reasonable strength, ductility and fabricability; affordable cost; and availability in large quantities.

Unalloyed zirconium was used as the structural material in the prototype core for nuclear submarines in 1953 (Rickover, 1975 in Adamson, 2010). However, variability in corrosion resistance, strength and cost issues prompted development of a stronger, more corrosion-resistant alloy named Zircaloy-2. This alloy was used in the first nuclear powered submarine, Nautilus 1954, and in the first commercial electricity-generating reactor, Shippingport 1957. Today, a variety of zirconium alloys (see below for details) are used in all LWRs throughout the world.

This chapter covers the following topics relevant to the uniqueness of zirconium alloys: Section 4.2 on fuel assembly design; Sections 4.3-4.6 on material and performance issues; Section 4.7 covers future trends in materi­als; and Section 4.8 provides sources of further information.

Zirconium and hafnium (used as a neutron absorber) are unique among materials used in LWRs in that they have the hexagonal close packed (HCP)

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