Irradiation-creep in a materials testing reactor

Lewthwaite, G.W.; Proctor, K.J.

doi:10.1016/0022-3115(73)90117-7

Cited by 17 publications

(4 citation statements)

References 7 publications

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“…Hesketh [1] first proposed the link between dislocation loops and irradiation creep in uranium. Lewthwaite and Proctor [2] extended the mechanism to austenitic steels where irradiation induced vacancies cluster to form voids that drive swelling, while interstitials cluster to form loops that drive irradiation creep. Herschbach and Schneider [3] further developed a method to calculate the strain contribution from dislocation loops while taking into account both the effect of irradiation and applied stress.…”

Section: Introductionmentioning

confidence: 97%

Anisotropic dislocation loop distribution in alloy T91 during irradiation creep

Was

2014

Journal of Nuclear Materials

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a b s t r a c tFerritic-martensitic (FM) steel T91 was subjected to irradiation with 3 MeV protons while under load at stresses of 100 MPa, 180 MPa, and 200 MPa. Transmission electron microscopy of crept T91 samples was conducted to determine the nature of the loops and to quantify the edge-on dislocation loop density as a function of their orientation to the tensile axis. Loops were determined to be interstitial in nature of the type a o h1 0 0i. The distribution of a o h1 0 0i loops was found to be strongly anisotropic in which loops preferentially formed with their normal in the tensile direction. An empirical correlation was developed to describe the relationship between the orientation of the loop normal to the tensile axis and the local dislocation loop density. Loop anisotropy was found to increase as a function of the applied stress and their strain contributions relative to total creep strain were calculated at 4-11% of the total creep strain. Results from this study provide a means for quantifying empirically measured anisotropic microstructure and including it in irradiation creep mechanisms for FM steels.Published by Elsevier B.V.

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Section: Introductionmentioning

confidence: 97%

Anisotropic dislocation loop distribution in alloy T91 during irradiation creep

Was

2014

Journal of Nuclear Materials

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“…By citing results presented by Lewthwaite and Proctor [ 40 ], where they showed a non-linear relationship of D/D e with dose (D is the creep deflection and D e the initial elastic deflection) of a weighted spring, Garner and Tolocyko [ 41 ] unfairly claimed that the results of Lewthwaite and Mosedale [ 36 ] on secondary steady state creep in the absence of swelling ( B 0 ) had been misinterpreted because they had not considered the transient, which was an artefact of the data analysis by Lewthwaite and Proctor. However, Lewthwaite and Mosedale [ 36 ] measured creep rates starting about 1000–2000 h after the start of the irradiation, and did not include the primary transient, which is a combination of both the elastic and anelastic deflection of the weighted spring and any additional transient that is observed during in-reactor creep tests up to about 2000 h [ 26 ].…”

Section: Microstructure Effects On Irradiation Creepmentioning

confidence: 99%

“…If there is a criticism to be made of Lewthwaite and Mosedale it is in the approximation that the secondary creep with dose was linear after an initial transient, when in fact it only becomes linear after the evolving dislocation loops have saturated (after 5–10 dpa). Garner and Tolocyko [ 41 ] confounded the two sets of results, the transient in the Lewthwaite and Proctor [ 40 ] data being an artefact of dividing D (the deflection) by D e (the initial offset), the latter being unrelated to the creep. The measurements of Mosedale and Lewthwaite [ 36 ] apply to the post-offset creep only and were not confounded by any initial offset giving rise to the transient in D/D e shown by Lewthwaite and Proctor [ 40 ].…”

Section: Microstructure Effects On Irradiation Creepmentioning

confidence: 99%

“…Garner and Tolocyko [ 41 ] confounded the two sets of results, the transient in the Lewthwaite and Proctor [ 40 ] data being an artefact of dividing D (the deflection) by D e (the initial offset), the latter being unrelated to the creep. The measurements of Mosedale and Lewthwaite [ 36 ] apply to the post-offset creep only and were not confounded by any initial offset giving rise to the transient in D/D e shown by Lewthwaite and Proctor [ 40 ]. The Mosedale and Lewthwaite [ 36 ] data show that the slope of the creep versus dose curve ( B 0 ) decreases with dose and approaches a constant value after a certain low dose that can be attributed to the hardening of the material due to the evolution of the dislocation loop structure [ 8 , 10 ].…”

Section: Microstructure Effects On Irradiation Creepmentioning

confidence: 99%

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Microstructural Effects on Irradiation Creep of Reactor Core Materials

Griffiths

2023

Materials

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The processes that control irradiation creep are dependent on the temperature and the rate of production of freely migrating point defects, affecting both the microstructure and the mechanisms of mass transport. Because of the experimental difficulties in studying irradiation creep, many different hypothetical models have been developed that either favour a dislocation slip or a mass transport mechanism. Irradiation creep mechanisms and models that are dependent on the microstructure, which are either fully or partially mechanistic in nature, are described and discussed in terms of their ability to account for the in-reactor creep behaviour of various nuclear reactor core materials. A rate theory model for creep of Zr-2.5Nb pressure tubing in CANDU reactors incorporating the as-fabricated microstructure has been developed that gives good agreement with measurements for tubes manufactured by different fabrication routes having very different microstructures. One can therefore conclude that for Zr-alloys at temperatures < 300 °C and stresses < 150 MPa, diffusional mass transport is the dominant creep mechanism. The most important microstructural parameter controlling irradiation creep for these conditions is the grain structure. Austenitic alloys follow similar microstructural dependencies as Zr-alloys, but up to higher temperature and stress ranges. The exception is that dislocation slip is dominant in austenitic alloys at temperatures < 100 °C because there are few barriers to dislocation slip at these low temperatures, which is linked to the enhanced recombination of irradiation-induced point defects.

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