Structural integrity assessment of pressure tubes for Wolsong Unit 1 based on operational experiences

Park, Youn Won; Kang, Sung Sik; Han, BongSup

doi:10.1016/s0029-5493(01)00477-0

Cited by 10 publications

(15 citation statements)

References 5 publications

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“…The integrity of zirconium alloy cladding in nuclear fuel rods during service can be degraded by DHC, a time dependent crack growth process. 2,5,[8][9][10][11] Although it has been observed in Zircaloy-2, 37,38,[44][45][46] Zircaloy-4 42,46 and Zr-2?5Nb, 2,5,[8][9][10][11][12][13][14][15]44 most of the work on DHC has been conducted on Zr--2?5Nb. The physical processes involved in the DHC failure mechanism are fairly well understood.…”

Section: General Characteristics Of Dhc In Zirconium Based Alloysmentioning

confidence: 99%

“…Figure 14 summarises the complex relationships between crack velocity and reciprocal temperature observed in Zr-2?5Nb 7 for Zircaloy-2 cladding tubes. 38,46 At temperatures below 318uC (604uF) or the TSSP, DHC velocity V, is dictated by the diffusion of hydrogen to the crack tip to form hydrides and is related to the absolute temperature according to the Arrhenius relation given by 12,38 V ~V0 exp {Q DHC RT (11) where Q DHC is the activation energy for DHC, V o is an empirical constant, T is absolute temperature and R is the universal gas constant. In general, DHC velocity decreases rapidly with decreasing temperatures because the diffusion of hydrogen to the crack tip is slow at low temperatures.…”

Section: Temperature Dependence Of Dhcmentioning

confidence: 99%

“…where da is the crack increment. The crack velocity V is given by equation (11) for T,T C , but is given by equation ( 12) for T C ,T,TSSD and V50 for T.TSSD.…”

Section: Temperature Dependence Of Dhcmentioning

confidence: 99%

“…Failure of Zr-2?5Nb pressure tubes in CANDU reactors has been reported and attributed to DHC. 2,5,[8][9][10][11] Many studies [7][8][9][10][12][13][14] of DHC kinetics in Zr-2?5Nb have been conducted, including a multinational round robin study, 15 to produce a consistent set of DHC rates for Zr-2?5Nb performed under the auspices of the International Atomic Energy Agency (IAEA).…”

Section: Introductionmentioning

confidence: 99%

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An assessment of delayed hydride cracking in zirconium alloy cladding tubes under stress transients

Chan

2013

International Materials Reviews

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Zirconium alloy cladding tubes used in nuclear fuel rods are susceptible to delayed hydride cracking, which is a time dependent crack growth process resulting from the stress assisted diffusion of hydrogen to the crack tip, followed by the formation of radial hydrides and the subsequent fracture of the hydrides in the crack tip region. This article reviews the current understanding of the delayed hydride cracking behaviour of zirconium alloy cladding tubes for fuel rods, focusing on the degradation mechanisms in high burnup fuel rods and transient loading scenarios, which could potentially lead to substantial changes in the hydride microstructure and cladding failure by delayed hydride cracking following removal from the reactor and during storage and disposal of spent nuclear fuel rods in a waste repository. A brief summary of the general characteristics of delayed hydride cracking in zirconium alloy cladding is presented first. Relevant information on the cladding stresses under various usage conditions is then compiled and categorised into several characteristic stress transients that can be anticipated during reactor operation. Delayed hydride cracking in cladding tubes under stress transients is then examined under various temperatures, cooling rates, burnup levels and loading conditions.

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Section: General Characteristics Of Dhc In Zirconium Based Alloysmentioning

confidence: 99%

Section: Temperature Dependence Of Dhcmentioning

confidence: 99%

“…where da is the crack increment. The crack velocity V is given by equation (11) for T,T C , but is given by equation ( 12) for T C ,T,TSSD and V50 for T.TSSD.…”

Section: Temperature Dependence Of Dhcmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An assessment of delayed hydride cracking in zirconium alloy cladding tubes under stress transients

Chan

2013

International Materials Reviews

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“…The operating experience 10 showed that 8% of the inspected tubes was affected by flaws greater than code allowable and about 60% was damaged by debris and 33% was in contact with calandria tube. It means that the pressure tube is exposed to various degradation mechanisms that are likely to develop cracks.…”

Section: Flaw Initiation and Growthmentioning

confidence: 99%

A Probabilistic Integrity Assessment of Flaw in Zirconium Alloy Pressure Tube Considering Delayed Hydride Cracking

Kwak

Lee

Kim

et al. 2003

Int. J. Mod. Phys. B

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In the CANDU nuclear reactor, pressure tubes of cold-worked Zr-2.5Nb material are used in the reactor core to contain the nuclear fuel bundles and heavy water coolant. Pressure tubes are major component of nuclear reactor, but only selected samples are periodically examined due to numerous numbers of tubes. Pressure tube material gradually pick up deuterium, as such are susceptible to a crack initiation and propagation process called delayed hydride cracking (DHC), which is the characteristic of pressure tube integrity evaluation. If cracks are not detected, such a cracking mechanism could lead to unstable rupture of the pressure tube. Up to this time, integrity evaluations are performed using conventional deterministic approaches. So it is expected that the results obtained are too conservative to perform a rational evaluation of lifetime. In this respect, a probabilistic safety assessment method is more appropriate for the assessment of overall pressure tube safety. This paper describes failure criteria for probabilistic analysis and fracture mechanics analyses of the pressure tubes in consideration of DHC. Major input parameters such as initial hydrogen concentration, the depth and aspect ratio of an initial surface crack, DHC velocity and fracture toughness are considered as probabilistic variables. Failure assessment diagram of pressure tube material is proposed and applied in the probabilistic analysis. In all the analyses, failure probabilities are calculated using the Monte Carlo simulation. As a result of analysis, conservatism of deterministic failure criteria is showed.

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Integrity evaluation system of CANDU reactor pressure tube

Kim

Kwak

Lee

et al. 2003

KSME International Journal

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Structural integrity assessment of pressure tubes for Wolsong Unit 1 based on operational experiences

Cited by 10 publications

References 5 publications

An assessment of delayed hydride cracking in zirconium alloy cladding tubes under stress transients

An assessment of delayed hydride cracking in zirconium alloy cladding tubes under stress transients

A Probabilistic Integrity Assessment of Flaw in Zirconium Alloy Pressure Tube Considering Delayed Hydride Cracking

Integrity evaluation system of CANDU reactor pressure tube

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