• Nuclear Engineering and Technology
• /
• v.45 no.6
• /
• pp.721-730
• /
• 2013

Within the framework of the ASTRID project, core design studies are being conducted by the CEA with support from AREVA and EDF. The pre-conceptual design studies are being conducted in accordance with the GEN IV reactor objectives, particularly in terms of improving safety. This involves limiting the consequences of 1) a hypothetical control rod withdrawal accident (by minimizing the core reactivity loss during the irradiation cycle), and 2) an hypothetical loss-of-flow accident (by reducing the sodium void worth). Two types of cores are being studied for the ASTRID project. The first is based on a 'large pin/small spacing wire' concept derived from the SFR V2b, while the other is based on an innovative CFV design. A distinctive feature of the CFV core is its negative sodium void worth. In 2011, the evaluation of a preliminary version (v1) of this CFV core for ASTRID underlined its potential capacity to improve the prevention of severe accidents. An improved version of the ASTRID CFV core (v2) was proposed in 2012 to comply with all the control rod withdrawal criteria, while increasing safety margins for all unprotected-loss-of-flow (ULOF) transients and improving the general design. This paper describes the CFV v2 design options and reports on the progress of the studies at the end of pre-conceptual design phase 1 concerning: - Core performance, - Intrinsic behavior during unprotected transients, - Simulation of severe accident scenarios, - Qualification requirements. The paper also specifies the open options for the materials, sub-assemblies, absorbers, and core monitoring that will continue to be studied during the conceptual design phase.

• Food Science and Preservation
• /
• v.17 no.4
• /
• pp.494-499
• /
• 2010

Pasteurization by radiation was performed to improve the microbiological quality of fresh yam juice. Samples were irradiated at doses of up to 5 kGy and microbiological, physicochemical, and sensory qualities were investigated during storage at 5oC for 8 days. Total aerobic bacterial, coliform bacterial, and yeast and mold counts in pre-irradiation samples were 7.09, 6.91, and 3.42 log CFU/g, respectively. Total aerobic bacterial and coliform counts fell significantly, in a dose-dependent manner, after irradiation, and these organisms were completely eliminated after 1 day of storage when 3 kGy or 5 kGy of radiation was applied. Yeast and molds were eliminated by irradiation at 3 kGy. Irradiation reduced sample viscosity. The $L^*$ value decreased after irradiation, whereas the $b^*$ value rose. Sensory evaluation testing revealed no significant difference between control samples and those irradiated with 1 kGy, except in color and texture, but sensory scores fell when irradiation of 3 kGy or over was employed, except in the taste domain. The results indicate that gamma irradiation with 1 kGy is effective to ensure the microbiological safety of fresh yam juice, without significant alteration in sensory characteristics, although further work should seek to reduce the detrimental effects of irradiation.

• Research in Plant Disease
• /
• v.20 no.4
• /
• pp.283-288
• /
• 2014

Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) has been quarantined by many countries in the world. Recently, the usage of methyl bromide should be limited, application by gamma irradiation on the agricultural production is raised as an alternative method. In this study, the level of gamma irradiation which could decrease of population of Xcc in the suspension or on the surface of citrus fruit was investigated. The $D_{10}$ value of Xcc, which is radiation dose required to reduce the number of the microorganism, was 55 and 28 Gy in the suspension and on the surface of citrus fruit, respectively. Furthermore, disease severity was suppressed on the citrus leaves inoculated with Xcc suspension pre-treated with gamma irradiation. Based on this study, it is suggested that Xcc on the citrus fruit could be eradicated by gamma irradiation and the results of this study may be valuable for application of gamma ray in quarantine activity.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.28 no.4
• /
• pp.379-383
• /
• 2014

The purpose of this study is to investigate the effects of silkworm extracts (SWE) on reactive oxygen species formation in mice (C57BL/6). Mice were administrated intraperitoneally with SWE (20 mg/kg/day) for 14 days. All animals were sacrificed 24 hours after the last SWE treatment and then extracted the blood and brain tissue in mouse. The researcher measured several parameters related to reactive oxygen species formation, malondialdehyde (MDA) and hydrogen peroxide ($H_2O_2$) contents in serum, whole brain, cerebral cortex and cerebellum. The results showed that MDA content of pre-SWE treatment was decreased significantly in serum, mitochondrial and cytosolic fraction of whole brain and cerebellum (P<0.01). The $H_2O_2$ content of pre-SWE treatment was decreased significantly in mitochondrial fraction of whole brain, cerebral cortex and cerebellum (P<0.01). These results suggest that SWE plays an important role for inhibition of oxidative damage of cells as well as antioxidant effect, aging delay and cells protected from irradiation.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.15 no.2
• /
• pp.1-8
• /
• 2019

The integrity of the Reactor Pressure Vessel (RPV) is affected by the neutrons bombarding the vessel wall leading to embrittlement. This irradiation-induced embrittlement leads to reduction in the fracture toughness of RPV materials. This paper presents a comparative study of typical Optimized Power Reactor (OPR)1000 reactor pressure-temperature (P-T) limit curves using the pre-2006 American Society of Mechanical Engineers (ASME) editions used in the power plant and the current ASME edition of 2010. The current ASME Code utilizes critical reference stress intensity factor based on the lower bound of static, while the Pre-2006 ASME editions are based the critical reference stress intensity factor based on the lower bound of static, dynamic and crack arrest. Model-Based Systems Engineering approach was used to evaluate ASME Code Section XI Appendix G for generating the P-T limit curves. The results obtained from this analysis indicate decrease in conservatism in P-T limit curves constructed using the current 2017 ASME code, which can potentially increase operational flexibility and plant safety. Hence it is recommended to use ASME code edition after 2006 be used in all operating nuclear power plants (NPPs) to establish P-T limit curve.

• Membrane Journal
• /
• v.21 no.2
• /
• pp.118-126
• /
• 2011

A method of light pre-irradiation, one of methods modifying hydrophobic surface to hydrophilic surface in a membrane, was proposed to overcome the drawback of previous methods such as blending, chemical treatment and post-irradiation, Process of membrane preparation in the study was comprised of 4 parts as follows: firstly process of precursor preparation to introduce hydrophilic nature under atmosphere and aqueous vapor by irradiating electron beam (EB), secondly process of dope solution preparation to cast on non-woven fabrics, thirdly process of casting to prepare membrane and finally process of coagulation in non-solvent to form porous structure. The merit of this method might show simple process as well as homogenous modification compared to previous methods. To carry it out, precursor was prepared by irradiating EB to powder PVDF at 75~125 K Gray dose. Precursor prepared was analyzed by FTIR, EDS and DSC to confirm the introduction of hydrophilic function and its mechanism. From their results, it was inferred I conformed that hydrophilic function was hydroxy1 and it was introduced by dehydrozenation. Hydrophilicity of membranes prepared was evaluated by contact angle (pristine PVDF : $62^{\circ}$, 125 K Gray-PVDF$13^{\circ}$). Porosity was evaluated by mercury intrusion method, simultaneously morpholoy and surface pore size were observed by SEM phothographs. The result showed the trend that more dose of EB led to smaller pore size and to lower porosity (pristine PVDF : 82%, 125 K Gray-PVDF : 63%). Trend of water permeability was similar to result above (pristine PVDF : 892 LMH, 125 K Gray-PVDF : 355 LMH).

• Korean Journal of Environmental Agriculture
• /
• v.15 no.1
• /
• pp.91-104
• /
• 1996

The viability loss or death of weed seeds buried in soil can be induced by infrared irradiation which has good penetration in moist soil. By using this principle of pre-emergence soil-treatment, the study was carried out to obtain basic information needed to develop the effective weed control method for the production of less polluted agricultural products. An apparatus for irradiating infrared was constructed by using ceramic material with high emissivity. The LPG was used as fuel for producing infrared by heating ceramic material. The soil heated in this study was loam with four levels of moisture contents (0.6, 5.7, 10.7, 15.1 % wb). The temperature distribution was measured at various soil depths when soil with different moisture content was irradiated with infrared for three different times (30, 60, 90 sec). The soil depths with duration time of minimum 3 minutes over $80^{\circ}C$, temperature inducing viability loss of weed seeds, were investigated. When the moisture content of soil was 0.6 and 5.7 % wb, the soil depths which can induce viability loss of weed seeds was greatly increased with increasing irradiation time. However, any depths of soil tested in this study was not reached to the temperature of $80^{\circ}C$ when 30 seconds of irradiation time was applied on soil with moisture content of 10.7 or 15.1 % wb. Generally, the soil depth needed for viability loss of weed seeds was decreased with increasing moisture content of soil. Also, longer irradiation time was required to induce viability loss of weed seeds with increasing moisture content of soil.

• Radiation Oncology Journal
• /
• v.20 no.1
• /
• pp.34-40
• /
• 2002

Purpose : This study was undertaken to retrospectively evaluate white blood ceil kinetics, especially lymphocyte depression after different treatments, and to find the correlation between immunosuppression and large blood volume and dynamic blood flow within the mediastinal radiotherapy (RT) field in lung cancer. Materials and Methods : Thirty-four patients with lung cancer were retrospectively evaluated; 10 patients had only radiotherapy (RT group), 8 had chemotherapy (CT group) and 16 fad chemotherapy and radio-therapy (RT/CT group). The mean follow-up periods of the RT-including groups (RT group and RT/CT group) and the RT-excluding group (CT group) were 6 and 8 months, respectively. Complete blood cell counts including lymphocyte percentage $(\%)$ were checked weekly during RT but less frequently during CT and after RT and after RT. Results : Changes in total white blood cell counts were not significantly different among the three groups. The lymphocyte count and lymphocyte $\%$ were much lower in the RT-including groups than in the RT-excluding group. The difference between pre-treatment and final lymphocyte count and the difference between pre-treatment and final lymphocyte $\%$ were significant (p=0.044 and p=0.037) between the RT-including groups and the RT-excluding group. Conclusion : lymphopenia was more marked after treatment containing RT than CT only. Lymphopenia may be one cause of a compromised immune system after mediastinal irradiation in lung cancer. We suggest cautiously that previous studies showing evidence of lymphocyte apoptosis after low-dose irradiation and large blood volume and dynamic blood flow within the RT fields could be somewhat related to lymphopenia after mediastinal irradiation.

• Korean Journal of Food Science and Technology
• /
• v.44 no.5
• /
• pp.532-539
• /
• 2012

Electron spin resonance (ESR) spectroscopy of gamma-irradiated fresh broccoli and kimchi cabbage was conducted to identify their irradiation history. Different pretreatments, such as freeze-drying (FD), oven-drying (OD), alcoholic-drying (ALD), and water-washing and alcoholic-drying (WAD) were used to lower the moisture contents of the samples prior to ESR analysis. The non-irradiated samples exhibited a single central signal ($g_0$=2.0007) with clear effect of $Mn^{2+}$, especially in kimchi cabbage. Upon irradiation, there was an increase in the intensity of the central signal, and two side peaks, mutually spaced at 6 mT, were also observed. These side peaks with $g_1$ (left)=2.023 and $g_2$ (right)=1.985 were attributed to radiation-induced cellulose radicals. Leaf and stem in broccoli, and root and stem in kimchi cabbage provided good ESR signal responses upon irradiation. The signal noise was reduced in case of ALD and WAD pretreatments, particularly due to $Mn^{2+}$ signals. The ALD treatment was found most feasible to detect the improved ESR spectra in the irradiated samples.

• Journal of Plant Biotechnology
• /
• v.49 no.4
• /
• pp.307-315
• /
• 2022

Artemisinin is a secondary metabolite of Artemisia annua that shows potent anti-malarial, anti-bacterial, antiviral, and anti-tumor effects. The supply of artemisinin depends on its content in Artemisia annua, in which various environmental factors can affect the plant's biosynthetic yield. In this study, the effects of different light-emitting diode (LED)-irradiation conditions were tested to optimize the germination and growth of Artemisia annua for the enhanced production of artemisinin. Specifically, the ratio between the red and blue lights in the irradiating LED was varied for investigation as follows: [Red : Blue] = [6 : 4], [7 : 3], and [8 : 2]. Furthermore, additional stress factors like UV-B-irradiation (1,395 ㎼/cm²), low temperature (4℃), and dehydration were also explored to induce hormetic expressions of ADS, CYP, and ALDH1, which are essential genes for the biosynthesis of artemisinin. Quantitative polymerase chain reaction (qPCR) was used to analyze the expression levels of the respective genes and their correlation with the specified conditions. [8 : 2] LED-irradiation was the most optimal among the tested conditions for the cultivation of Artemisia annua in terms of both fresh and dry weights post-harvest. For the production of artemisinin, however, [7 : 3] LED-irradiation with dehydration for six hours pre-harvest was the most optimal condition by inducing around twofold enhancement in the biosynthetic yield of artemisinin. As expected, a correlation was observed between the expression levels of the genes and the contents of artemisinin accumulated.