• Title/Summary/Keyword: Delayed hydride cracking

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Effect of an Increased Wall Thickness on Delayed Hydride Cracking in Zr-2.5Nb Pressure Tube (Zr-2.5Nb 중수로 압력관의 수소지연파괴에 미치는 압력관 두께의 영향)

  • Jeong, Yong-Hwan;Kim, Young-Suk
    • Nuclear Engineering and Technology
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    • v.27 no.2
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    • pp.226-233
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    • 1995

  • The wall thickness of a pressure tube is increased in order to reduce the probability of failure in a pressure tube of CANDU type reactor. It is presented here that the variation of wall thickness changes stress, hydrogen concentration and delayed hydride cracking in Zr-2.5Nb pressure tube. When the wall thickness is increased from 4.2 mm to 5.2 mm, the stress exerted on the tube and the deuterium taken up during operation are reduced by 19％. Further, the calculated allowable depth of the surface flaw over which delayed hydride cracking(DHC) is susceptible increases by 50％. DHC initiation is controlled by the stress and by the hydrogen concentration in the pressure tube. The results are therefore very significant in such a respect that increased wall thickness may reduce DHC initiation. Ac the wall thickness increases the hydrostatic tension will increase. Its impact on the acceleration of the crack growth rate of DHC deserves further studies.

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