Interaction of transmutation products with precipitates, dislocations and grain boundaries in neutron irradiated W

Lloyd, Matthew J.; London, Andrew J.; Haley, Jack C.; Gilbert, Mark R.; Becquart, Charlotte; Domain, Christophe; Saez, Enrique Martinez; Moody, Michael P.; Bagot, P.A.J.; Nguyen-Manh, D.; Armstrong, David E.J.

doi:10.1016/j.mtla.2022.101370

Cited by 20 publications

(7 citation statements)

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“…First principles calculations showed that the short-range order (SRO) parameter between Re and vacancy was negative, showing an attractive effect on vacancy [ 46 ]. Neutron irradiation experiments also showed that the voids could be decorated by Re and Os atoms [ 47 , 48 ]. Therefore, the aggregation of Re atoms and the formation of voids were mutually promoted under the irradiation of high-dose ions.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Rhenium Content on Microstructural Changes and Irradiated Hardening in W-Re Alloy under High-Dose Ion Irradiation

Luo

Liu

et al. 2023

Nanomaterials

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An amount of 100 dpa Si2+ irradiation was used to study the effect of transmutation rhenium content on irradiated microscopic defects and hardening in W-xRe (x = 0, 1, 3, 5 and 10 wt.%) alloys at 550 °C. The increase in Re content could significantly refine the grain in the W-xRe alloys, and no obvious surface topography change could be found after high-dose irradiation via the scanning electron microscope (SEM). The micro defects induced by high-dose irradiation in W and W-3Re alloys were observed using a transmission electron microscope (TEM). Dislocation loops with a size larger than 10 nm could be found in both W and W-3Re alloy, but the distribution of them was different. The distribution of the dislocation loops was more uniform in pure W, while they seemed to be clustered around some locations in W-3Re alloy. Voids (~2.4 nm) were observed in W-3Re alloy, while no void was investigated in W. High-dose irradiation induced obvious hardening with the hardening rate between 75% and 155% in all W-xRe alloys, but W-3Re alloy had the lowest hardening rate (75%). The main reasons might be related to the smallest grain size in W-3Re alloy, which suppressed the formation of defect clusters and induced smaller hardening than that in other samples.

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Section: Discussionmentioning

confidence: 99%

The Effect of Rhenium Content on Microstructural Changes and Irradiated Hardening in W-Re Alloy under High-Dose Ion Irradiation

Luo

Liu

et al. 2023

Nanomaterials

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“…Thus, accurate prediction of transmutation in W will be vital for fusion engineering. Samples of pure W (both single crystal and polycrystalline) were irradiated for 208 full-power days in 2008-9 in the High Flux Reactor (HFR) in Petten, Netherlands, and received a total estimated damage dose of 1.67 displacements per atom (dpa) from a neutron energy spectrum with a typical fission profile peaked at 1-2 MeV and a low-energy peak of thermal neutrons [42][43][44][45]. Later, in 2012-13, two single crystal W samples were irradiated to doses of 0.1 ('low dose') and 1.8 ('high dose') dpa, respectively, in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Lab in the US, which has a similar fission neutron energy profile but with typically a more pronounced (dominant) thermal Maxwellian [46].…”

Section: Reactormentioning

confidence: 99%

“…FISPACT-II inventory calculations were performed to simulate the irradiation (and decay-cooling) in both cases, which were possible due to accurate knowledge of the irradiation histories the samples received over several operational cycles of each reactor, and also through good representation of the neutron environments (see [45,46] for details). It was particularly critical to obtain the correct neutron spectra for these cases due to the importance of the low energy fluxes (below 1 keV) where the neutron-capture cross sections-the ones that dominate the transmutation in these fission environments-are highest.…”

Section: Reactormentioning

confidence: 99%

“…The specific isotope ratios predicted by FISPACT-II were used to guide the fitting of the APT data, demonstrating another important benefit of having reliable simulations. In [45], the analysis was even extended to obtain the concentration of individual isotopes by ranging each mass peak individually, and again the comparison to the simulated distribution is remarkable.…”

Section: Reactormentioning

confidence: 99%

“…Table 1 shows the simulation versus experiment comparison obtained from these two separate experiments. The table shows the calculated Re and Os concentrations, which are the primary transmutation elements in these fission-spectrum experiments (Ta was also measured in [45], but the observed and simulated concentrations were only around 0.01 atomic %). The comparison of the simulations (performed with TENDL nuclear data libraries) to experiment is generally very good, particularly in the low dose samples irradiated in HFIR.…”

Section: Reactormentioning

confidence: 99%

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Nuclear data for fusion: inventory validation successes and future needs

Gilbert

2023

J. Phys. Energy

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Nuclear data, describing neutron reaction probabilities (cross sections) and decay behaviour, are critical to the design and operation of fusion experiments and future fusion power plants. Equally vital, are the inventory codes that use the data to predict neutron-induced activation and transmutation of materials, which will define the radiological hazards that must be managed during reactor operation and decommissioning. Transmutation, including gas production, combined with the neutron-induced displacement damage, will also cause the properties of materials to degrade, for example through swelling and embrittlement, eventually limiting the lifetime of components. Thus validated and accurate nuclear data and inventory codes are essential.For data validation there are decay heat measurements performed at FNS in Japan more than 20 years ago. The experiments produced an invaluable database for benchmarking of nuclear data libraries; the latest versions of several international libraries perform well against this data during tests with the FISPACT-II inventory code, although there is still scope for improvement. A recent attempt to provide fusion-relevant validation based on \(\gamma\)-spectroscopy data from neutron-irradiated material samples tests production predictions of short-lived (several hours or less) radionuclides. The detailed analysis performed for molybdenum demonstrates how these data could eventually provide a new benchmark, and also illustrates the potential benefits of further experiments targeting the longer-lived radionuclides relevant to maintenance and decommissioning timescales.There are also some successful tests of transmutation predictions with FISPACT-II. These direct validations of inventory simulations are critical for lifetime predictions and future experiments should learn lessons from the examples described for tungsten, which demonstrate the importance of an accurate description of the neutron spectrum in experiments. More novel experimental techniques are needed to measure helium production in materials such as Fe and C, but the need to validate the nuclear data evaluations used by simulations should motivate future experimental efforts.

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