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The effect of neutron irradiation on hydride reorientation and mechanical property degradation of zirconium alloy cladding

  • Jang, Ki-Nam (Dongguk University, Department of Nuclear and Energy System Engineering) ;
  • Kim, Kyu-Tae (Dongguk University, Department of Nuclear and Energy System Engineering)
  • Received : 2016.05.28
  • Accepted : 2017.05.23
  • Published : 2017.10.25

Abstract

Zirconium alloy cladding tube specimens were irradiated at $380^{\circ}C$ up to a fast neutron fluence of $7.5{\times}10^{24}n/m^2$ in a research reactor to investigate the effect of neutron irradiation on hydride reorientation and mechanical property degradation. Cool-down tests from $400^{\circ}C$ to $200^{\circ}C$ under 150 MPa tensile hoop stress were performed. These tests indicate that the irradiated specimens generated a smaller radial hydride fraction than did the unirradiated specimens and that higher hydrogen content generated a smaller radial hydride fraction. The irradiated specimens of 500 ppm-H showed smaller ultimate tensile strength and plastic strain than those characteristics of the 250 ppm-H specimens. This mechanical property degradation caused by neutron irradiation can be explained by tensile hoop stress-induced microcrack formation on the hydrides in the irradiation-damaged matrix and subsequent microcrack propagation along the hydrides and/or through the matrix.

Acknowledgement

Supported by : National Research Foundation of Korea (NRF)

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