• Nuclear Engineering and Technology
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• v.48 no.2
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• pp.330-338
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• 2016

The U-Zr or U-TRU-Zr cylindrical metallic fuel slug used in fast reactors is known to swell significantly and to grow during irradiation. In neutronics simulations of metallic-fueled fast reactors, it is assumed that the slug has swollen and contacted cladding, and the bonding sodium has been removed from the fuel region. In this research, a realistic burnup-dependent fuel-swelling simulation was performed using Monte Carlo code McCARD for a single-batch compact sodium-cooled breed-and-burn reactor by considering the fuel-swelling behavior reported from the irradiation test results in EBR-II. The impacts of the realistic burnup-dependent fuel swelling are identified in terms of the reactor neutronics performance, such as core lifetime, conversion ratio, axial power distribution, and local burnup distributions. It was found that axial fuel growth significantly deteriorated the neutron economy of a breed-and-burn reactor and consequently impaired its neutronics performance. The bonding sodium also impaired neutron economy, because it stayed longer in the blanket region until the fuel slug reached 2% burnup.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3723-3740
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• 2021

The harsh conditions in the reactor affect the thermal and mechanical performance of the fuel plate heavily. Some in-pile behaviors, like fission-induced swelling, can cause a large deformation of fuel plate at very high burnup, which may even disturb the flow of coolant. In this research, the emphasis is put on the thermal expansion, fission-induced swelling, interaction layer (IL) growth, creep of the fuel meat, and plasticity of the cladding for the U₃Si₂/Al dispersion fuel plate. A detailed model of the fuel meat swelling is developed. Taking these in-pile behaviors into consideration, the three-dimensional large deformation incremental constitutive relations and stress update algorithms have been developed to study its thermal-mechanical performance under normal conditions using Abaqus. Results have shown that IL can effectively decrease the thermal conductivity of fuel meat. The high Mises stress region mainly locates at the interface between fuel meat and cladding, especially around the side edge of the interface. With irradiation time increasing, the stress in the fuel plate gets larger resulting from the growth of fuel meat swelling but then decreases under the effect of creep deformation. For the cladding, plasticity deformation does not occur within the irradiation time.

• Macromolecular Research
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• v.9 no.5
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• pp.253-258
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• 2001

Crosslinked poly(ethylene glycol)s (PEGs) were prepared by ultraviolet irradiation of low molar mass, liquid PEGs in the presence of benzophenone (BP) as a photoinitiator. The networks obtained have been characterized by DSC, IR, and contact angle measurements, and their water absorption and equilibrium swelling have been examined. The percent of gel formed and degree of swelling of the networks in water were dependent on the amount of BP in the reaction mixture, irradiation time and molar mass of PEG. Gel fraction yield exceeded 84%, and equilibrium swelling in water varied from 49 to 244%.

• Journal of Biomedical Engineering Research
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• v.39 no.4
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• pp.161-167
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• 2018

Polyvinyl alcohol/sodium carboxymethyl cellulose (PVA/NaCMC) hydrogels were prepared by physical crosslinking (cyclic freezing/thawing) and gamma (${\gamma}$)-ray irradiation to evaluate the effect of NaCMC concentration (2~8 wt%) on the mechanical properties and the biocompatibility of the PVA/NaCMC hydrogels. The swelling rate of PVA/NaCMC hydrogels regardless of irradiation rose with increasing NaCMC content from 2 wt% to 8 wt%, while the gelation rate was the reverse. As the NaCMC content increased from 2 wt% to 6 wt%, the compressive strength of the hydrogels increased dramatically from $8.5{\pm}2.0kPa$ to $52.7{\pm}2.5kPa$ before irradiation and from $13.5{\pm}2.9kPa$ to $65.5{\pm}8.7kPa$ after irradiation. When 8 wt% NaCMC was added afterwards, the compressive strength decreased however. The irradiated PVA/NaCMC hydrogels containing 6 wt% NaCMC exhibited the tailored properties of the swelling rate of $118{\pm}3.7%$, the gelation rate of $71.4{\pm}1.3%$, the strength of $65.5{\pm}8.7kPa$, respectively, and no cytotoxicity was observed.

• Macromolecular Research
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• v.16 no.2
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• pp.139-148
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• 2008

Biodegradable and elastic poly(L-lactide-co-$\varepsilon$-caprolactone) (PLCL) was electrospun to prepare nanofibers, and N-isopropylacrylamide (NIPAAm) was then grafted onto their surfaces under aqueous conditions using $^{60}Co-{\gamma}$ irradiation. The graft yield increased with increasing irradiation dose from 5 to 10 kGy and the nanofibers showed a greater graft yield compared with the firms. SEM confirmed that the PLCL nanofibers maintained an interconnected pore structure after grafting with NIPAAm. However, overdoses of irradiation led to the excessive formation of homopolymer gels on the surface of thc PLCL nanofibers. The equilibrium swelling and deswelling ratio of the PNIPAAm-g-PLCL nanofibers (prepared with 10 kGy) was the highest among the samples, which was consistent with the graft yield results. The phase-separation characteristics of PNIPAAm in aqueous conditions conferred a unique temperature-responsive swelling behavior of PNIPAAm-g-PLCL nanofibers, showing the ability to absorb a large amount of water at < $32^{\circ}C$, and abrupt collapse when the temperature was increased to $40^{\circ}C$. In accordance with the temperature-dependent changes in swelling behavior, the release rate of indomethacin and FITC-BSA loaded in PNIPAAm-g-PLCL nanofibers by a diffusion-mediated process was regulated by the change in temperature. Both model drugs demonstrated greater release rate at $40^{\circ}C$ relative to that at $25^{\circ}C$. This approach of the temperature-controlled release of drugs from PNIPAAm-g-PLCL nanofibers using gamma-ray irradiation may be used to design drugs and protein delivery carriers in various biomedical applications.

• Nuclear Engineering and Technology
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• v.41 no.2
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• pp.155-162
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• 2009

Since the 90's, EDF and AREVA-NP have irradiated, up to very high burnups, lead assemblies housing $M5^{(R)}$ cladded fuels. Post-irradiation examination of high burnup $UO_2$ pellets show an increase in the fission-gas release rate, an increase in fuel swelling, and formation of fission-gas bubbles throughout the pellets. Xenon abundances were quantified, and phenomena leading to this bubble formation were identified. All examinations provided valuable data on the complex state of the fuel during irradiation. They show the good behavior of these fuels, exhibiting various microstructures at very high burnups, none of which is likely to lead to problems during irradiation.

• Journal of Radiation Industry
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• v.2 no.1
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• pp.15-19
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• 2008

In order to develop a water-solubility and biocompatibility, chemically modified chitosan, N,O-carboxymethylchitosan (NOCC), was synthesized and the NOCC hydrogels were prepared by using ${\gamma}-ray$ irradiation instead of chemical reagents. The FT-IR spectroscopy, swelling behavior, gel content and mechanical property such as gel strength of the hydrogel were measured. When the NOCC solution concentration was 15 wt% and the dose of irradiation was less than 50 kGy, the NOCC hydrogels had an excellent hydrophilicity and exhibited a good swelling behavior and mechanical properties.

• Nuclear Engineering and Technology
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• v.24 no.1
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• pp.40-51
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• 1992

One of the important irradiation performance characteristics of the silicide dispersion fuel element in research reactors is the diameteral increase resulting from fuel swelling. This paper, will attempt to develop a physical model for the fuel swelling, DFSWELL, by analyzing the basic irradiation behaviours and some experimental evidences. From the experimental evidences, it was shown that the volume changes in irradiated U$_3$Si-Al were strongly dependent on temperature and fission rate. The quantitative-amount of swelling for silicide fuel is estimated by considering temperature, fission rate, solid fission product build-up and gas bubble behavior. The swelling for the silicide fuel is comprised of three major components : i ) a volume change due to the formation of an interfacial layer between the fuel particle and matrix. ii ) a volume change due to the accumulation of gas bubble nucleation iii ) a volume change due to the accumulation of solid fission products The DFSWELL model which takes into account the above three major physical components predicts well the absolute magnitude of silicide fuel swelling in accordance with the power histories in comparison with the experimental data.

• Journal of Plant Biotechnology
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• v.41 no.1
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• pp.44-49
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• 2014

In this study, we investigated the effects of sodium hypochlorite (NaOCl) and red or blue light-emitting diode (LED) light on embryo swelling and germination of Oreorchis patens (Lindl.) Lindl. A method for determining the swelling and protocorm formation in O. patens seeds through in vitro examination of immature seeds was established. NaOCl treatment of immature seeds was found to significantly enhance the extent of embryo swelling and protocorm formation in immature zygote embryos compared to those in the untreated controls. Additionally, the effects of white fluorescent light, and red and blue LED lights on embryo swelling and protocorm formation in in vitro cultured seeds were examined and compared to the conditions with or without NaOCl treatment. The most suitable light for embryo swelling and protocorm formation was the red LED light.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.1
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• pp.71-87
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• 1995

The purpose of this study was to investigate the early irradiation changes on the ultrastructure of the capillary endothelial cell in the rat submandibular glands. For the study, 110 Sprague-Dawley strain male rats were singly irradiated to their neck regions with the doses of 2Gy, 5Gy, and 10Gy by 6MV X -irradiation, and sacrificed on the 3 hours, 6 hours, 12 hours, 1 day, 3 days, 7 days, and 14 days after irradiation. The authors observed the histologic and ultrastructural changes of the capillary endothelial cell using the light and electron microscopes. The results were as follows: I. In the light microscopic examination, the capillary dilation was observed on the 6 hours group and the capillary density was slightly increased on the 12 hours group after 2Gy and 5Gy irradiation. And luminal size and capillary density were decreased on the 3 days and the 7 days groups after irradiation, after then, they were recovered. But capillary density was still decreased on the 14 days group after 10Gy irradiation. 2. In the transmission electron microscopic examination, the mild proliferation of cytoplasmic process of the endothelial cell and reduction in luminal size were observed on the 3 hours group after irradiation. After then, endothelial swelling, marked proliferation of cytoplasmic process, thickened basal lamina, and numerous pinocytotic vesicles were observed after the 1 day group after irradiation. Thickened basal lamina and numerous pinocytotic vesicles were still observed until the 7 days group after irradiation. These changes were recovered to normal on the 14 days group after 2Gy and 5Gy irradiation, but not after 10Gy irradiation. 3. In the scanning electron microscopic examination, the dilation of conduits and constriction, and meandering were observed on the 1 day group after 10Gy irradiation. These changes were observed with increased coarseness of the surface of the vascular resin casting on the 3 days group after irradiation. 4. From the above results, endothelial swelling, proliferation of cytoplasmic process, and thickening of the basal lamina appeared before the 6 hours group after irradiation. And these changes may also induce the increase of the capillary number and luminal size, after then, capillary permeability was increased via the increase of the number of pinocytotic vesicles. The changes were observed earlier and more apparent with the increase of the irradiation doses under the dose of 10Gy irradiation.