Effects of displacement damage and helium production rates on the nucleation and growth of helium bubbles – Positron annihilation spectroscopy aspects

Kršjak, Vladimír; Degmová, Jarmila; Sojak, Stanislav; Slugeň, V.

doi:10.1016/j.jnucmat.2017.11.007

Cited by 43 publications

(22 citation statements)

References 45 publications

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“…The hydrogen nuclei were chosen for ion implantation due to almost the same mass of protons and neutrons and minimize the effect of injected interstitials, known from the heavy-ion bombardment experiments [36]. In order to minimize the dpa rate effect [20], the neutron damage was compared to hydrogen (proton) implantation of the same fluence. The irradiation conditions were, however, still very distinct, resulting in rather different defects in the microstructure.…”

Section: Specimenmentioning

confidence: 99%

“…Relevant parameters of ions implantation can be much better controlled than the real neutron irradiation in the power reactor and the evolution of the damaged features can even be observed in situ. One of crucial factor is the penetration depth of ions implantation which depends on the type and energy of the particles used: electrons [18], light ions (H, He) [8,19,20], and heavy (or self) ions [21], the typical low energy proton beam or several MeV self-ions damaged layers have a thickness of the order of one micrometer below the surface of the irradiated sample. So, the detailed microstructural evolutions in this narrow modified layer (~µm) should be characterized by depth-sensing methods.…”

Section: Introductionmentioning

confidence: 99%

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Radiation Damage of Reactor Pressure Vessel Steels Studied by Positron Annihilation Spectroscopy—A Review

Slugeň

Sojak

Egger

et al. 2020

Metals

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Safe and long term operation of nuclear reactors is one of the most discussed challenges in nuclear power engineering. The radiation degradation of nuclear design materials limits the operational lifetime of all nuclear installations or at least decreases its safety margin. This paper is a review of experimental PALS/PLEPS studies of different nuclear reactor pressure vessel (RPV) steels investigated over last twenty years in our laboratories. Positron annihilation lifetime spectroscopy (PALS) via its characteristics (lifetimes of positrons and their intensities) provides useful information about type and density of radiation induced defects. The new results obtained on neutron-irradiated and hydrogen ions implanted German steels were compared to those from the previous studies with the aim to evaluate different processes (neutron flux/fluence, thermal treatment or content of selected alloying elements) to the microstructural changes of neutron irradiated RPV steel specimens. The possibility of substitution of neutron treatment (connected to new defects creation) via hydrogen ions implantation was analyzed as well. The same materials exposed to comparable displacement damage (dpa) introduced by neutrons and accelerated hydrogen ions shown that in the results interpretation the effect of hydrogen as a vacancy-stabilizing gas must be considered, too. This approach could contribute to future studies of nuclear fission/fusion design steels treated by high levels of neutron irradiation.

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Section: Specimenmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radiation Damage of Reactor Pressure Vessel Steels Studied by Positron Annihilation Spectroscopy—A Review

Slugeň

Sojak

Egger

et al. 2020

Metals

Self Cite

View full text Add to dashboard Cite

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“…Several experimental tools including small-angle neutron scattering [10][11][12], positron annihilation spectrometry [13][14][15], grazing incidence small-angle X-ray scattering, and transmission electron microscopy (TEM) are available to study the behavior of helium bubbles in metals or alloys [16][17][18]. Among these tools, TEM is typically employed to capture helium bubble images for investigating their morphological evolution at the nanometer scale spatial resolution [19,20].…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of helium bubbles in transmission electron microscopy images based on machine learning method

Bai

Zhang

et al. 2021

NUCL SCI TECH

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Helium bubbles, which are typical radiation microstructures observed in metals or alloys, are usually investigated using transmission electron microscopy (TEM). However, the investigation requires human inputs to locate and mark the bubbles in the acquired TEM images, rendering this task laborious and prone to error. In this paper, a machine learning method capable of automatically identifying and analyzing TEM images of helium bubbles is proposed, thereby improving the efficiency and reliability of the investigation. In the proposed technique, helium bubble clusters are first determined via the density-based spatial clustering of applications with noise algorithm after removing the background and noise pixels. For each helium bubble cluster, the number of helium bubbles is determined based on the cluster size depending on the specific image resolution. Finally, the helium bubble clusters are analyzed using a Gaussian mixture model, yielding the location and size information on the helium bubbles. In contrast to other approaches that require training using numerous annotated images to establish an accurate classifier, the parameters used in the established model are determined using a small number of TEM images. The results of the model formulated according to the proposed approach achieved a higher F1 score validated through some helium bubble images manually marked. Furthermore, the established model can identify bubble-like objects that humans cannot facilely identify. This computationally efficient method achieves object recognition for material structure identification that may be advantageous to scientific work.

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“…We can use Fe ion irradiation to simulate neutron irradiation-induced lattice displacement. The production of transmutation helium in the material can be effectively simulated by He ion implantation [ 8 , 9 , 10 ]. Due to the simultaneous occurrence of lattice disorder and helium accumulation, simultaneous dual-beam implantation of Fe and He seems to be an optimal procedure for an experimental simulation of realistic radiation condition.…”

Section: Introductionmentioning

confidence: 99%

Comparison between Subsequent Irradiation and Co-Irradiation into SIMP Steel

et al. 2021

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A modern Chinese ferritic/martensitic steel SIMP, is a new perspective nuclear structural material for the spallation target in accelerator driven sub-critical system. In this work, aimed at exploring the radiation resistance properties of this material, we investigate the differences between simultaneous Fe and He ions irradiation and He implantation of SIMP steel pre-irradiated by Fe self-ions. The irradiations were performed at 300 °C. The radiation-induced hardening was evaluated by nano-indentation, while the lattice disorder was investigated by transmission electron microscopy. Clear differences were found in the material microstructure after the two kinds of the ion irradiation performed. Helium cavities were observed in the co-irradiated SIMP steel, but not the case of He implantation with Fe pre-irradiation. In the same time, the size and density of Frank loops were different in the two different irradiation conditions. The reason for the different observed lattice disorders is discussed.

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Effects of displacement damage and helium production rates on the nucleation and growth of helium bubbles – Positron annihilation spectroscopy aspects

Cited by 43 publications

References 45 publications

Radiation Damage of Reactor Pressure Vessel Steels Studied by Positron Annihilation Spectroscopy—A Review

Radiation Damage of Reactor Pressure Vessel Steels Studied by Positron Annihilation Spectroscopy—A Review

Statistical analysis of helium bubbles in transmission electron microscopy images based on machine learning method

Comparison between Subsequent Irradiation and Co-Irradiation into SIMP Steel

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