Effect Of Irradiation Temperature Research Articles

Structural damage and bubble evolution in SiC-ZrC composite irradiated with 500 keV He-ions at various temperatures

Ceramic composites with high temperature strengths and low neutron cross-sections are promising candidates for core materials in advanced nuclear systems. In present work, SiC-20 vol% ZrC composites were irradiated with 500 keV He-ions at 25, 500 and 800 °C to evaluate the effect of irradiation temperature on the structural damage and bubble evolution in ceramic composites. XRD and Raman spectra analysis give that the irradiation resulted in structural damages of both SiC and ZrC. TEM observations reveal the formation of helium bubbles and defect clusters after irradiation. Moreover, the occurrence of micro-cracks in ZrC grains and amorphization of SiC are observed for the samples irradiated at room temperature. Nanoindentation test showed that there is irradiation induced hardening or softening of the composites which depends on the irradiation temperature or fluence. The correlation between microstructural evolution and mechanical properties response is discussed.

Effect of irradiation temperature on the mobility of structural and vacancy defects in the damaged layer of Li2ZrO3 ceramics

The paper presents the assessment results of the irradiation temperature effect on the change in the type of structural defects caused by irradiation with helium ions in the near-surface layer of Li2ZrO3 ceramics, as well as determining the nature of structural damage using the electron paramagnetic resonance method in the case of irradiation fluence variation. During characterization of the structural changes caused by helium ion irradiation, the main attention was paid to detailing the type of structural defects and radiolysis products arising during irradiation, alongside alterations in their concentration using the electron paramagnetic resonance method. During the experiments, it was determined that the observed effects of thermally stimulated mobility of vacancy defects in the damaged layer caused by irradiation with helium ions indicate a positive effect of thermal heating of samples during irradiation at low fluences. This effect consists in a decline in the number of oxygen vacancies in the damaged layer at low irradiation fluences (1015 – 1016 cm-2), the concentration of which was determined using the EPR method, and the observed structural changes at low irradiation fluences in the case of an elevation in irradiation temperatures are associated with deformation distortion of the crystalline structure of ceramics caused by transformation energy processes, and thermal expansion effects.

Comprehensive characterization of the irradiation effects of glassy carbon

Carbon materials have become increasingly diverse, finding applications in high-temperature and high-radiation environments. Glassy carbon, an allotrope known for its exceptional chemical inertness and desirable mechanical properties. However, understanding neutron irradiation effects in glassy carbon has proven challenging, primarily because of its unique nanopore structure. This study presents a highly detailed microstructural characterization investigation of neutron-induced changes in glassy carbon, revealing how changes in nanopore structure and crystallinity impact the irradiation-induced shrinkage. Aberration-corrected scanning transmission electron microscopy (STEM) reveals pore closure that leads to material densification in the irradiated samples. Dimensional analysis combined with comparison to historical data suggest significant length shrinkage to occur. Neutron and in situ electron irradiation experiments suggest that glassy carbon transforms into so-called carbon onions, supporting the concept of shrinkage saturation. Investigating irradiation temperature effects using STEM, electron energy loss spectroscopy, x-ray diffraction, and Raman spectroscopy revealed partial amorphization at 210 °C–230 °C and preserved order in glassy carbon at 860 °C, coinciding with pore closure. Thermal property measurements were also conducted to assess the effects of densification and other changes in the atomic structure of glassy carbon. The results of this study have broad implications in the deployment of glassy carbon to nuclear environments, based around the observed changes in the thermal properties, and demonstrates the operational window for the onset of densification.

Study of irradiation temperature effect on radiation-induced polymorphic transformation mechanisms in ZrO2 ceramics

The influence of high-dose exposure to heavy Xe23+ ions on the alteration in optical and structural properties, alongside the polymorphic transformation degree in polycrystalline ZrO2 ceramics is considered in the paper. The focus on such studies is primarily due to the possibility of obtaining new data on the mechanisms of radiation-induced damage associated with exposure to heavy ions comparable to fission fragments of nuclear fuel, alongside the comparison of the observed changes in the damaged layer properties with the polymorphic transformation processes characteristic of ZrO2 ceramics. Analysis of the obtained data on alterations in the optical and structural features of ceramics contingent upon irradiation conditions revealed that, the irradiation temperature leads to less pronounced structural degradation caused by deformation distortions of OI-Zr-OI, Zr-OII, Zr-OI/OII and Zr-OI bonds, as well as the accumulation of oxygen vacancies in the damaged layer. At the same time, using a set of research methods, it was determined that at irradiation temperatures above 700 K the processes of polymorphic transformations t – ZrO2→ c – ZrO2 caused by radiation and deformation effects are less pronounced, which results in the formation of inclusions in the form of t – ZrO2.

Differences in coupling between nuclear and electronic energy losses in UO2 with irradiation temperature: An in situ TEM study

To investigate the coupling between nuclear and electronic energy losses in UO2, we irradiated thin foils with 0.39 MeV Xe and/or 6 MeV Si ions at 93 K using single or simultaneous dual beam ion irradiations. The evolution of perfect dislocation loops was characterized by in situ transmission electron microscopy (TEM). Additional ex situ TEM characterizations at room temperature revealed for the first time in UO2 the presence of faulted Frank loops too small to be measured during in situ experiments and conventional bright field kinematical imaging conditions.For the single Xe irradiation, which favor dominant ballistic energy losses, we observed a continuous nucleation of small perfect dislocation loops, which increase in size for our last fluences by growing through mainly coalescence effect. Both the single Si and dual Xe & Si irradiations showed a coupling between nuclear and electronic energy losses, resulting in a significant loop density increase and a tangled line network formation, respectively. These phenomena occur at lower dpa levels, compared to the single Xe irradiation, likely resulting from the thermal spike effect of Si ions. The present results were compared to our previous work at 293 K to investigate the role of irradiation temperature on the energy losses coupling. For the Xe irradiation, the density increases and the loops are smaller at 93 K compared to 293 K, resulting from the uranium interstitials mobility being prevented or allowed. For the Si irradiation, the dislocation evolution kinetics are similar at both temperatures. The electronic excitations effect seems greater than the irradiation temperature effect in this temperature range. For the Xe & Si irradiation, the loop kinetics change resulting in a tangled line network formation is faster and thus the loop transformation into lines occurs at lower dpa levels at 93 K compared to 293 K. It appears that the irradiation temperature affecting the mobility of some small point defects reduces the electronic excitation effect in this case.

A facility for cryogenic ion irradiation and in situ characterization of rare-earth barium copper oxide superconducting tapes.

Superconducting magnets based on Rare Earth Barium Copper Oxides (REBCO) offer transformative capabilities in the fields of fusion energy, high energy physics, and space exploration. A challenge shared by these applications is the limited lifetime of REBCO due to radiation damage sustained during operation. Here we present a new ion-beam facility that enables simultaneous cryogenic irradiation and in situ characterization of commercial REBCO tapes. The ion source provides spatially uniform fluxes up to 1018protons/m2s with kinetic energies up to 3.4MeV, in addition to helium and higher-Z species. Using this facility, we can induce uniform damage profiles in the first 10-20 µm of REBCO tapes with less than 0.25 appm of hydrogen implanted in REBCO after a dose of 1020protons/m2. The tape can be held between 20 and 300K with an accuracy of ±0.1K and is connected to a four-point probe measuring the critical current, Ic, and critical temperature, Tc, before, during, and after irradiation with transport current ranging from 100 nA to 100A, and a typical voltage noise less than 0.1 μV. These capabilities are presently used to study the effect of irradiation temperature on REBCO performance change during and after proton bombardment, to assess the possibility of Ic and Tc recovery after irradiation through thermal annealing, and to explore the instantaneous and recoverable suppression of Ic and Tc observed during irradiation.

Analysis of night behavior and negative running for PVT system

High absorption of PV benefits heat collection in the daytime, but the heat loss to the space/environment because of its high emissivity also should be noticed. Although there are many papers investigating PVT, few of them cover the night behavior and negative running during late afternoon. This paper supplements detailed studies on related content to draw people's attention to the night and late-afternoon operation that helps better strategy establishment and less heat loss. From experiments, the clouds help hinder the PV radiant heat exchange with space. Under clear night, the PV bottom temperature can be 6.88 °C lower than air temperature and the water tank's bottom temperature drops 2.8 °C. Because of the fluid viscosity, no apparent temperature stratification and flow occur in the PVT water pipe, causing even PV temperature. The higher the water temperature, the easier the negative running occurs during late afternoon, although the irradiation is still high at 521W/m2. Heat loss power and energy are −199W and 1791 KJ from 15:10 to 17:40. Based on different regressed linear correlations of different PVT systems, the effect of water temperature, irradiation, and ambient temperature on the negative performance is also comparatively studied.

An In Situ transmission electron microscopy study on the synergistic effects of Au-ion irradiation and high temperature on nuclear graphite microstructure

The combined effects of high-temperature and heavy-ion irradiation on Mrozowski cracks (MC) and nuclear graphite crystallographic dimensions have been studied using in situ heating and in situ ion-irradiation in the transmission electron microscope (TEM). Electron transparent lamella of nuclear graphite, IG-110, was irradiated using a 2.8 MeV Au beam at an ion flux of 3.991 ×1010 ion cm−2 s−1 for 70 min at 800 °C. Upon high-temperature irradiation, Mrozowski crack closure was studied quantitatively. The analysis showed linear, positive expansion of nuclear graphite which is significantly different from the dimensional changes previously reported for low-dose neutron irradiation of nuclear graphite in which the material undergoes negative to positive expansion via a turnaround radiation dose. The trend of the thermal expansion coefficient (CTE) of pristine IG-110 in this study is consistent with previous reports in the 100 °C–800 °C temperature region in which the dimensional change ranges from negative to positive values.

Experimental emulation of 10B(n, α)7Li reaction-induced microstructural evolution of Al-B4C neutron absorber used in the dry storage of spent nuclear fuel

Al-B4C neutron absorber in spent fuel dry storage could suffer significant radiation damage at elevated temperature (∼150–300 °C) mainly via 10B(n, α)7Li reactions. Several recent studies reported significant bubble formation in the absorber, however only from wet storage environment at near ambient temperature (< ∼90 °C). In this study, we irradiated a commercially widely used Al-B4C absorber of interest utilizing 120-keV helium ion-beam accelerator with twelve different conditions; three different doses (0.01, 0.1, and 1 dpa) combined with four different temperatures (room temperature, 150, 270, and 400 °C). This was to investigate the irradiation-induced microstructural evolution of the absorber in dry storage environment in expedited manner instead of time-consuming neutron irradiation test. The effects of irradiation dose and temperature on helium bubble nucleation and growth were investigated by image analysis on BF-TEM images, which showed a typical tendency of increasing bubble size with increasing temperature at the expense of decreasing bubble number density. Helium bubble morphology at grain boundaries was quite similar with the ones reported from the previous studies on the surveillance coupons used in the wet environment, elliptic helium bubbles around B4C particles. Notable difference was the prominent formation of numerous helium bubbles even from the lowest dose (0.01 dpa) at slightly elevated temperature (150 °C), perhaps due to higher irradiation temperature than that of spent fuel pool. This study may experimentally confirm that significant bubble formation and growth in the absorber could be the case from the early stage of the dry storage, even without the participation of hydrogen produced from the absorber corrosion. Particularly in the case of non-clad Al-B4C absorber, possible B4C particle detachment may need to be concerned since the bubble coalescence was concentrated at the interface between Al alloy matrix and B4C particle which would be microcracked under neutron irradiation.

Effect of Irradiation Temperature and Atmosphere on Aging of Epoxy Resins for Superconducting Magnets.

The superconducting magnets of future particle accelerators will be exposed to high irradiation doses at cryogenic temperatures. To investigate the effect of irradiation temperature and atmosphere on the aging behavior, we have characterized the changes in thermomechanical properties of six epoxy resins for potential use in superconducting magnets after irradiation up to 20 MGy in ambient air, inert gas, and liquid helium. Based on the results obtained by Dynamic Mechanical Analysis (DMA), we discuss the effect of irradiation temperature and the presence of oxygen. The irradiation temperature can have a strong influence on the rates at which cross-linking and chain scission occur.

Helium swelling behavior for neutron multipliers after irradiation with He ions at high temperatures

Beryllides as beryllium intermetallic compounds are the advanced multiplier materials as candidate materials for fusion demonstration power plant (DEMO) due to having good properties such as low swelling rate and stable chemical properties.Under DEMO operation environment, the generated He amounts in beryllium are estimated around 20,000 appm He. This study was evaluated the effect of He fluence and irradiation temperature on the bubble behaviors in Be12Ti and beryllium. The irradiation of He ion was carried out using an In-situ transmission electron microscope equipped with an ion gun by implantation up to 25,000 appm He. For comparison, beryllium was carried out in similar experiments.Bubbles were observed in Be12Ti at 873 K after the implantation of 15,000 appm He, while in Be at the same temperature, their appearance occurred post-implantation of 4,500 appm He. In addition, growth of bubbles in beryllium was observed with increase of He ion fluence. Sizes and densities of bubbles in Be12Ti and beryllium were evaluated irradiated in 25,000 appm He at 673 and 873 K.In the case of Be12Ti, fine bubbles were observed in a high density state, and it was found that the swelling rate was a few percent. By contrast, bubbles in beryllium had a diameter in the range from tens to several tens nanometers, and growth of these bubbles were observed. The swelling rate of beryllium was approximately 18 %.

Irradiation dose and temperature effects on BCC material with dislocation based crystal plasticity

Numerical modelling of temperature and strain rate dependent plasticity of body centered cubic (BCC) materials is carried out based on dislocation based crystal plasticity model. In view of the strong influence of radiation effects on the response of BCC materials, the constitutive equations are further extended to incorporate the effect of irradiation-induced defects. Size of irradiation defects produced (mainly dislocation loops) is mostly controlled by the irradiation temperature, whereas the defect number density is governed by the irradiation dose. The present constitutive model is introduced to predict the irradiation conditions and temperature dependent plasticity for BCC materials. The model is used to simulate the different irradiation conditions in terms of dislocation loop size and number density. To have a quantitative effect of irradiation conditions on material toughness, the Defect Induced Apparent Temperature Shift (ΔDIAT) is estimated and compared with available experimental evidence, for validation.

Combined Radiation and Temperature Effects on Brillouin-Based Optical Fiber Sensors

The combined effects of temperature (from −80 °C to +80 °C) and 100 kV X-ray exposure (up to 108 kGy(SiO2)) on the physical properties of Brillouin scattering and losses in three differently doped silica-based optical fibers, with varying dopant type and concentration (4 wt%(Ge), 10 wt%(Ge) and 1 wt%(F)), are experimentally studied in this work. The dependencies of Brillouin Frequency Shifts (BFS), Radiation-Induced Attenuation (RIA) levels, Brillouin gain attenuation, Brillouin frequency temperature (CT) and strain (Cε) sensitivity coefficients are studied under X-rays in a wide temperature range [−80 °C; +80 °C]. Brillouin sensing capabilities are investigated using a Brillouin Optical Time Domain Analyzer (BOTDA), and several properties are reported: (i) similar behavior of the Brillouin gain amplitude decrease with the increase in the RIA; (ii) the F-doped and heavily Ge-doped fibers do not exhibit a temperature dependence under radiation for their responses in Brillouin gain losses. Increasing Ge dopant concentration also reduces the irradiation temperature effect on RIA. In addition, Radiation-Induced Brillouin Frequency Shift (RI-BFS) manifests a slightly different behavior for lower temperatures than RIA, presenting an opportunity for a comprehensive understanding of RI-BFS origins. Related temperature and strain sensors are designed for harsh environments over an extended irradiation temperature range, which is useful for a wide range of applications.

A novel thermoelectrical model for dye-sensitized solar cells for consideration of the effects of solar irradiation, wavelength, and surface temperature

The present study aims to provide an innovative model to simulate the behavior of dye-sensitized solar cells, considering their advantages and the emerging technology of cells. The new model uses carrier particle continuity equations and the Butler-Volmer equation to examine the effects of solar radiation, wavelength, and temperature on cell performance. Power Conversion Efficiency (PCE) is studied for sunny and cloudy days (7 am to 6 pm) based on input and output power. Parametric changes, including fill factor, open circuit voltage, and short circuit, are calculated in this regard. The good agreement observed between the outcomes of previous studies and the results obtained here emphasizes the reliability of the proposed model. As a striking novelty, the impact of transparent conductive oxide (TCO) recombination current on cell performance parameters is also examined using the Butler-Volmer equation under normal and diffuse radiation (low light). The results reveal that the effect of recombination current is more significant for diffuse radiation conditions than the clear sky (sunny day). For example, the efficiency and voltage drop are higher for the cloudy mode. The sunny weather has a reduction of about 0.2 % in efficiency, while the same state for the cloudy weather is about 1.8 %.

Predictive modeling of PV solar power plant efficiency considering weather conditions: A comparative analysis of artificial neural networks and multiple linear regression

This study investigates the surface parameters and environmental factors affecting the energy production of a 500 kWp photovoltaic (PV) solar power plant in Igdir province. Using both the PV panel characteristics and the weather conditions specific to the power plant location, a total of 7 detailed features were included. The estimation of the power plant efficiency, a novel contribution not found in previous studies, is also a major focus. The performance evaluation of different models, including feed-forward neural networks and multiple linear regression, demonstrates the effectiveness of artificial neural networks in capturing the complex relationships between features and efficiency despite limited data availability. Principal Component Analysis (PCA) was used to reduce feature dimensions, showing that even with a reduced feature set, accurate efficiency prediction is still achievable. Prediction using PCA is one of the novelties of the paper. The effects of solar irradiation, module power, and module temperature on power plant efficiency are revealed. The results provide valuable insights for optimizing energy investments in the Igdir region and highlight the potential of artificial neural networks in energy forecasting, demonstrating their suitability for capturing complex patterns in solar power plant efficiency.

Combined Photobleaching and Temperature Effects on 1550 nm Radiation-Induced Attenuation of Germanosilicate Optical Fiber

Combined temperature and photobleaching (PB) effects on the 1550 nm radiation-induced attenuation (RIA) levels and kinetics of a commercial Ge-doped single-mode optical fiber have been investigated. The main goal of this study was to evaluate if synergetic effects could impact the performances of free space optical communication links in space. For this, we performed accelerated (0.5 Gy(SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )/s) irradiation runs with 100 kV X rays up to the total ionizing dose of 150 kGy(SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), varying the irradiation temperature between -80 °C and 80 °C. First, we evaluate the irradiation temperature effects: infrared RIA largely increases at negative temperatures. Second, the effects of injecting different optical powers at the different temperatures have been characterized: if at temperatures exceeding room temperature (RT), PB effects are almost negligible, a PB effect is clearly observable at lower temperatures where the germanosilicate optical fiber present large RIA levels due to the contribution of metastable defects absorbing at 1550 nm. Increasing the injected powers allows reducing the concentration of these radiation-induced unstable defects, but not as much as thermal treatment consecutive to the irradiation. These results highlight the complex physics of radiation induced defects absorbing at 1550 nm in Ge-doped optical fiber, but also the vulnerability of this class of fiber for space telecommunication links. Regarding the unstable nature of point defects causing the RIA at lower temperature, it seems possible to mitigate the loss excess by thermal cycles at RT or higher temperatures. We also could expect that our accelerated tests represent a worst-case scenario in terms of RIA levels at the maximum dose.

Dose dependences for materials of vver pressure vessels and their support structures

The basic equations for structural integrity assessment on brittle fracture criterion are presented. The main mechanisms of radiation and thermal embrittlement of materials used for WWER RPV (15Kh2MFA, 15Kh2NMFA grade steels and its weld metal) and their support structures (St.3, 09G2S grade steels and its weld metal). The main considerations for construction of the trend curves are given and various types of trend curves are presented. The trend curves taken into account metallurgical and operational factors, such as content of alloying and impurity elements, neutron fluence, operating time and irradiation temperature. The analysis of the neutron flux effect under different dominant mechanisms of embrittlement of RPV materials is presented. The effect of irradiation temperature on contribution of different mechanisms of radiation embrittlement typical for materials of WWER RPV and SS is considered.

Performance analysis of a hybrid solar-driven cooler for refrigerator vehicle

This study focused on investigating the annual performance of a novel hybrid solar-driven cooling system that can be used on refrigerator vehicles. The cooling system is mainly driven by a DC compressor which is powered by a PV array, while an AC compressor which is powered by the car alternator assists the cooling system when the cooling load is higher than the capacity of the DC compressor. Detailed electrical modeling of the PV panels in the array is performed based on an algorithm that comprises a set of mathematical equations and is validated against the manufacturer's test data. The detailed transient electrical power generation of the PV array is analyzed. The effect of solar irradiation and ambient temperature on the performance of the PV modules is presented. Considering the refrigeration cycle, detailed thermodynamics and heat transfer analysis on the cycle are carried out. The effect of ambient temperature and refrigerator compartment temperature on the performance of the refrigeration cycle is investigated. It is concluded that an increase in ambient temperature decreases the performance of both the PV panel and the refrigeration cycle. While an increase in refrigerator compartment temperature increases the performance of the refrigeration cycle.

Degradation of electrical resistivity of tungsten following shielded neutron irradiation

A major challenge for heat transfer in nuclear materials is to ensure thermal mobility after high amounts of neutron irradiation. Tungsten is widely selected as a heat transfer material in fusion reactors. In metals, thermal conductivity is dominated by electrons’ ability to transfer energy. Neutron irradiation generates point defects, clusters, and solid transmutation (e.g.rhenium and osmium in tungsten), which inhibit electron motion. The purpose of this work is to quantify the irradiation-induced change in electron mobility and deconvolute transmutation and microstructural effects on observed changes to electron mobility. Single and polycrystalline tungsten were fast neutron irradiated in the High Flux Isotope Reactor at Oak Ridge National Laboratory to doses between 0.2 and 0.7 displacements per atom (dpa) and temperatures from 500 °C to 1000 °C. Grain growth was observed in all samples. Microstructure and transmutation were quantified. The geometric orientation of samples with elongated grains has been shown to affect electrical resistivity. A mathematical model was developed and used to deconvolute solid-solution transmutation, grain, and temperature-dependent lattice effects on resistivity. At ∼0.4 dpa at ∼590 °C, the combined resistivity degradation due to voids, vacancies, interstitials, and dislocations is estimated to be greater than the contribution from solid solution Re transmutation, which is greater than the contribution from grain boundaries. At doses of ∼0.7 dpa at ∼750 °C, solid solution Re contributions are greater than all other effects combined. This work establishes a basis to predict the effects of irradiation temperature and transmutation on thermal properties of tungsten and highlights the importance of irradiation temperature.

Effects of neutron irradiation and high temperature on structure and magnetic properties of Sm2Co17 permanent magnet

In this work, the effects of neutron irradiation and high temperature on the magnetic properties and structure of Sm2Co17 permanent magnets (PMs) were investigated. The phase composition in Sm2Co17 PMs does not change after neutron irradiation with fluence of 5 × 1014n/cm2. The magnetic domain structure and Mössbauer spectra of Sm2Co17 PMs were almost kept the same after neutron irradiation. The neutron irradiation almost does not influence the intrinsic coercivity and magnetic flux ϕ of Sm2Co17 PMs. When temperatures increase from room temperature to 300 °C, intrinsic coercivity Hcj, remanence Br and maximum energy product (BH)max have 52.8 %, 5.6 % and 15.4 % deterioration, respectively. Magnetic flux ϕ decreases by 4.1 %. When temperature increases to 550 °C, compared with room temperature, Hcj, Br and (BH)max decrease 88.8 %, 21.8 % and 54.3 %, respectively. ϕ has a 40 % deterioration.