ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 3 June 2010
Page Count: 20

The Effect of Microstructure on Delayed Hydride Cracking Behavior of Zircaloy-4 Fuel Cladding—An International Atomic Energy Agency Coordinated Research Program

Coleman, C.
Researcher Emeritus, Chalk River Laboratories (CRL), AECL, Chalk River, ON

Grigoriev, V.
Senior Specialist, Studsvik Nuclear AB, Nyköping,

Inozemtsev, V.
Nuclear Fuel Specialist, International Atomic Energy Agency (IAEA), Vienna,

Markelov, V.
Head of Department, The Joint Stock Company A. A. Bochvar High-Technology Research Institute of Inorganic Materials (JSC VNIINM), Moscow,

Roth, M.
Head, Materials Testing Group, Institute for Nuclear Research (INR), Romanian Authority for Nuclear Activities (RAAN), Piteşti,

Makarevicius, V.
Senior Researcher, Laboratory of Materials Research and Testing, Lithuanian Energy Institute (LEI), Kaunas,

Kim, Y. S.
Head, Zirconium Team, Korea Atomic Energy Research Institute (KAERI), Daejeon,

Liaqat Ali, Kanwar
Senior Researcher, Pakistan Institute of Nuclear Science and Technology (PINST), Islamabad,

Chakravarrty, J. K.
Head, Mechanical Metallurgy Section, Materials Group, Bhabha Atomic Research Centre (BARC), Mumbai,

Mizrahi, R.
Senior Researcher, Materials Dept., National Atomic Energy Commission (CNEA-CAC), San Martín, Pcia. de Buenos Aires

Lalgudi, R.
General Manager, Materials Science and Technology Centre, Energy and Nuclear Research Institute (ENRI), Sao Paulo,

(Received 30 January 2010; accepted 8 April 2010)

Abstract

The rate of delayed hydride cracking (DHC) has been measured in Zircaloy-4 fuel cladding in several metallurgical conditions using the pin-loading tension technique. In light water reactor (LWR) cladding in the cold-worked and cold-worked and stress-relieved conditions, the cracking rate followed Arrhenius behavior up to about 280 °C, but at higher temperatures the rate declined with no cracking above 300°C. Non-LWR cladding appeared to behave in the same manner. In LWR cladding in the recrystallized condition, the cracking rate was highly variable because it depended on K_I within the test range up to 25 MPa√m, whereas in the other LWR claddings, cracking rate was independent of K_I, indicating that K_IH was below 11 MPa√m. The main role of microstructure was to control the material strength; the cracking rate increased as the strength increased. Although all the claddings had a radial texture, it did not protect the cladding from DHC. The DHC fracture surface consisted of flat broken hydrides, often in arcs, but no striations were observed, except in one specimen subjected to thermal cycles.

Keywords:
Zircaloy-4 fuel cladding, delayed hydride cracking (DHC), pin-loading tension (PLT), microstructure, temperature dependence, KI dependence

Paper ID: JAI103008
DOI: 10.1520/JAI103008
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