Hydride Reorientation and Delayed Hydride Cracking of Spent Fuel Rods in Dry Storage

Kim, Young S.

doi:10.1007/s11661-009-0044-6

Cited by 8 publications

(9 citation statements)

References 33 publications

(57 reference statements)

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“…However, Rothman (1984) noted that additional data are necessary for larger crack depths (~50% of wall thickness)…. Kim (2009) has proposed a new model for DHC. In this model, creep deformation, prior creep strain, higher burnup, the solvus hysteresis, and the γ to δ hydride phase transition all play important roles in DHC.…”

Section: Cladding H 2 Effects: Delayed Hydride Crackingmentioning

confidence: 99%

“…In this model, creep deformation, prior creep strain, higher burnup, the solvus hysteresis, and the γ to δ hydride phase transition all play important roles in DHC. While there is much disagreement (EPRI 2002b;McRae et al 2010) with Kim's model (Kim 2009), if Kim's hypotheses are correct, then spent fuel will be more likely to fail by DHC upon cooling below 180°C if there are stress raisers inside the rod such as the end cap weld region or incipient cracks due to an interaction of fuel and cladding during reactor operation. "…”

Section: Cladding H 2 Effects: Delayed Hydride Crackingmentioning

confidence: 99%

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Draft evaluation of the frequency for gas sampling for the high burnup confirmatory data project

Stockman

Alsaed

Bryan

2015

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This report fulfills the M3 milestone M3FT-15SN0802041, "Draft Evaluation of the Frequency for Gas Sampling for the High Burn-up Storage Demonstration Project" under Work Package FT-15SN080204, "ST Field Demonstration Support-SNL". This report provides a technically based gas sampling frequency strategy for the High Burnup (HBU) Confirmatory Data Project. The evaluation of: 1) the types and magnitudes of gases that could be present in the project cask and, 2) the degradation mechanisms that could change gas compositions culminates in an adaptive gas sampling frequency strategy. This adaptive strategy is compared against the sampling frequency that has been developed based on operational considerations. Gas sampling will provide information on the presence of residual water (and byproducts associated with its reactions and decomposition) and breach of cladding, which could inform the decision of when to open the project cask. Initial Condition After drying (using the vacuum drying process as opposed the forced helium dehydration process), sealing, leak testing, and backfilling the cask with high purity helium, there may be two types of gases within the cask cavity: 1) fission gases (mainly 85 Kr) released from breached fuel rods, and 2) residual water and its decomposition products formed by corrosion or radiolysis (e.g., H 2 and O 2). The initial conditions relevant to gas sampling frequency will be established after the cask has been backfilled with helium while the cask is inside the North Anna decontamination building. Gas Types, Magnitudes, and Detection Limits The minimum detectible concentration of 85 Kr without using high sensitivity measurement methods is less than one pCi/cm 3. At this detection limit, even if as little as 1% of 85 Kr in a single pellet were to be released, it would be detectible (assuming the 85 Kr gas is uniformly distributed within the cask). Therefore, potential 85 Kr concentrations (initial and subsequent due to potential cladding failures) will be detectable with standard measurement methods. The detectible concentration of water without using high sensitivity measurement methods is about one part per million (ppm). If the NRC drying guidelines are followed, the total unbound water within the cask should be below 0.25 volume percent which is about 11 parts per thousand, an amount easily detected in a gas sample. Gas Distribution and Sampling Location The potential for gas segregation, which would confound the collection of a representative gas sample, is evaluated in this report. It is concluded that neither gravitational settling nor thermal diffusion would result in any significant gas segregation. Therefore, sampling the gas from the top of the TN-32 project cask will provide a reasonably representative concentration for 85 Kr, H 2 O, O 2 , and H 2 throughout the cask. Degradation Mechanisms That Could Change Gas Compositions The degradation mechanisms for the components within the cask were evaluated for any information that could be gained from gas sampling and may be useful f...

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Section: Cladding H 2 Effects: Delayed Hydride Crackingmentioning

confidence: 99%

Section: Cladding H 2 Effects: Delayed Hydride Crackingmentioning

confidence: 99%

Draft evaluation of the frequency for gas sampling for the high burnup confirmatory data project

Stockman

Alsaed

Bryan

2015

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“…Chao et al (Chao 2008) report that the location of the crack is important in determining whether or not the cladding will breach, with the greatest chance being when the crack is located on the outer side of the cladding. Kim (2009) has proposed a new model for DHC. In this model, creep deformation, prior creep strain, higher burnup, the solvus hysteresis, and the γ to δ hydride phase transition all play important roles in DHC.…”

Section: Hydrogen Effects: Delayed Hydride Crackingmentioning

confidence: 99%

BWR Spent Nuclear Fuel Integrity Research and Development Survey for UKABWR Spent Fuel Interim Storage

Bevard

Mertyurek

Belles

et al. 2015

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“…The absorption of hydrogen during service in water-cooled reactors and the subsequent precipitation of zirconium hydride in the outer periphery once the hydrogen solubility is exceeded, results in hydrogen embrittlement of the cladding. The thermal creep phenomena occurring during vacuum drying operations also induced radial hydride reorientation susceptible to DHC [18]. Under lower temperatures hydride reorientation and Delayed Hydride Cracking (DHC) has been shown to happen at a crack tip by a process of stress-induced hydride phase transformation from to -ZrH 2 [17].…”

Section: Temperaturementioning

confidence: 99%

“…Also, the pellet-clad mechanical interaction (PCMI) at BU > 47 MWd/KgU [8] induces incipient cracks on the inside cladding surface, which are susceptible for hydride reorientation and subsequent crack growth [18,22]. Also, the pellet-clad mechanical interaction (PCMI) at BU > 47 MWd/KgU [8] induces incipient cracks on the inside cladding surface, which are susceptible for hydride reorientation and subsequent crack growth [18,22].…”

Section: Burn Upmentioning

confidence: 99%

Changes in spent nuclear fuel due to dry interim storage

et al. 2012

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The assessment of the main changes expected for spent nuclear fuel from its discharge to its deposition in a deep geological repository is of the outmost relevance to establish the initial conditions of the disposal. In this work, a literature review and a critical discussion of the main processes that will affect the structure and the inventory of the spent nuclear fuel during its interim dry storage is presented. Once the irradiation period is finished, the following changes are observed: i) the fuel pellet is fragmented due to the temperature gradient established during the irradiation stage. On average between 10-15 fragments are observed per pellet. ii) the initial gap existing between the pellet and the cladding decreases or disappears depending on the burnup. iii) a radial zonation is observed in the microstructure of the pellet. For burnup over 40MWd/KgU, the rim develops a porosity increase due to the high local burnup and the low temperature in the periphery. The rim also presents small bubbles of fission gases. This high burnup structure implies a degradation of the thermic conductivity in the pellet, that leads to a temperature increase in the center of the pellet with a subsequent migration of the fission gases and other impurities to the grain boundaries. The implications that all these changes may have on the spent fuel behaviour is presented and discussed. Figure 1: Schematic illustration of the microstructure of spent fuel and the distribution of actinides and fission products following burn-up in a reactor [9,10].

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Hydride Reorientation and Delayed Hydride Cracking of Spent Fuel Rods in Dry Storage

Cited by 8 publications

References 33 publications

Draft evaluation of the frequency for gas sampling for the high burnup confirmatory data project

Draft evaluation of the frequency for gas sampling for the high burnup confirmatory data project

BWR Spent Nuclear Fuel Integrity Research and Development Survey for UKABWR Spent Fuel Interim Storage

Changes in spent nuclear fuel due to dry interim storage

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