Selenium (Se) is known as an antioxidant mineral and heme iron is a major source for iron intake which can promote carcinogenesis in the body. This study was to investigate the effect of Se on heme-aggravated colon carcinogenesis in mice. Three experimental groups included control [normal diet + AOM (10 mg/kg body weight in saline)/DSS (2% in the drinking water)], [AOM/DSS + hemin (534 mg/kg body weight in CMC)], and [AOM/DSS + hemin + Se (2.82 mg/kg diet in CMC)] groups. Colonic mucosa were stained with 0.3% methylene blue and the colonic polyps, aberrant crypt (AC) and aberrant crypt foci (ACF) were counted. Lipid peroxidation in liver was evaluated by the thiobarbituric acid-reactive substances (TBARS) assay. The number of polyps in the hemin + Se group was 31.6% lower than that in the control group, and 41.4% lower than that in the hemin group. The number of AC in the hemin + Se group was 42.8% lower than that in the control group, and 49.1% lower than that in the hemin group. The number of ACF in the hemin + Se group was 49.0% lower than that in the control group, 45.7% than that in the hemin group. Hepatic TBARS level in the hemin + Se group was significantly low compared with the control group or the hemin group (p<0.05). These findings suggest that Se treatment may be protective against colon carcinogenesis promoted by a high heme-containing diet.

본 연구는 신생아 검사 중 포수클로랄(chloral hydrate)을 투여 후 진행되는 신생아 진정 검사 대비 진정 대체 방식 중 하나인 피드 및 랩(feed and wrap) 방식의 유용성을 평가한 연구이다. 본 연구에선 진정으로 진행한 신생아의 두뇌 T2 축면 영상과 피드 및 랩 방식으로 진행한 같은 영상 각 30개의 운동 허상(motion artifact)과 백질과 회백질의 구분 정도를 두 명의 영상의학과 전문의가 정성적으로 평가하였고, 운동 허상을 측정하기 위해서 위상부호화(phase encoding) 방향의 배경 영역(background area)의 평균 신호 강도(mean signal intensity)를 구하여서 정량적 방식으로 평가하였다. 또한 총검사 시간을 정리한 뒤 정량적 방식으로 평가하였고 투약 기록의 여부와 간호일지를 토대로 피드 및 랩 방식의 총 39건의 검사 건수 대비 성공률을 측정하였다. 운동 허상의 정량적 평가와 영상 품질의 정성적 평가 모두에서 두 집단은 유의미한 차이가 없었으나, 검사 시간의 정량적 평가에선 p값이 0.001로 유의한 차이가 있었다. 피드 및 랩 방식의 총검사 건수 대비 성공률은 100%였다. 결론적으로 본 논문에선 피드 및 랩 방식과 진정 방식의 영상 품질이 유의한 차이가 없고 성공률이 높기에 유용하다고 판단하였으나, 검사 시간이 더 지연되는 한계가 있다는 사실을 확인하였다.

Porous carbons are considered promising for CO2 capture due to their high-pressure capture performance, high chemical/ thermal stability, and low humidity sensitivity. But, their low-pressure capture performance, selectivity toward CO2 over N2, and adsorption kinetics need further improvement for practical applications. Herein, we report a novel dual-templating strategy based on molten salts (LiBr/KBr) and hydrogen-bonded triazine molecules (melamine–cyanuric acid complex, MCA) to prepare high-performance porous carbon adsorbents for low-pressure CO2. The comprehensive investigations of pore structure, microstructure, and chemical structure, as well as their correlation with CO2 capture performance, reveal that the dual template plays the role of porogen for multi-hierarchical porous structure based on supermicro-/micro-/meso-/ macro-pores and reactant for high N/O insertion into the carbon framework. Furthermore, they exert a synergistic but independent effect on the carbonization procedure of glucose, avoiding the counter-balance between porous structure and hetero-atom insertion. This enables the preferred formation of pyrrolic N/carboxylic acid functional groups and supermicropores of ~ 0.8 nm, while retaining the micro-/meso-/macro-pores (> 1 nm) more than 60% of the total pore volume. As a result, the dual-templated porous carbon adsorbent (MG-Br-600) simultaneously achieves a high CO2 capture capacity of 3.95 mmol g− 1 at 850 Torr and 0 °C, a CO2/ N2 (15:85) selectivity factor of 31 at 0 °C, and a high intra-particle diffusivity of 0.23 mmol g− 1 min− 0.5 without performance degradation over repeated use. With the molecular scale structure tunability and the large-scale production capability, the dual-templating strategy will offer versatile tools for designing high-performance carbon-based adsorbents for CO2 capture.

According to IAEA PRIS, there is no record of dismantling commercial heavy water reactors among 57 heavy water reactors around the world. In Canada, which has the largest number of heavy water reactors, three of the 22 commercial heavy water reactors with more than 500 MW are permanently suspended, Gentilly unit 2 (2012), Pickering unit 2 (2007), and Pickering unit 3 (2008), all of which chose a delayed decommissioning strategy. On the other hand, Wolsong unit 1, which will be the world’s first heavy water reactor to be dismantled commercially, will be immediately carried out as a decommissioning strategy. KHNP has established various cooperation systems with advanced companies and international organizations related to overseas NPP decommission and is actively exchanging technologies. Among them, the most important focus is on research cooperation related to COG (CANDU owners Group). The first case is a joint study on Conceptual Calandria Segmentation. Four areas of process, waste management, ALARA, and cost for decommissioning reactors to be submitted to Canadian regulators for approval of Pickering and Gentilly-2’s preliminary decommissioning plan have been evaluated, and research on Wolsong unit 1 is currently underway. The second case is Decommissioning and long-term waste management R&D. Although the technical maturity is low, it studies the common interests of member companies in the decommissioning of heavy water reactor power generation companies and long-term waste management. Robotics for dismantling high-radiation structures, C- 14, H-3 measurement and removal methods, and concrete decontamination technology, which are characterized by heavy water, are being actively studied. KHNP is strengthening international cooperation with COG to prepare for the successful decommissioning of Wolsong unit 1. Based on previous studies by Pickering and Gentilly-2, an evaluation of the decommissioning of Wolsong unit 1 reactor is being conducted. In addition, it is preparing for decommissioning through experience analysis of the pressure tube replacement project.

KHNP is carrying out international technical cooperation and joint research projects to decommission Wolsong unit 1 reactor. Construction data of the reactor structures, experience data on the pressure tube replacement projects, and the operation history were reviewed, and the amount of dismantled waste was calculated and waste was classified through activation analysis. By reviewing COG (CANDU owners Group) technical cooperation and experience in refurbishment projects, KHNP’s unique Wolsong unit 1 reactor decommissioning process was established, and basic design of a number of decommissioning equipment was carried out. Based on this, a study is being conducted to estimate the worker dose of dismantling workers. In order to evaluate the dose of external exposure of dismantling workers, detailed preparation and dismantling processes and radiation field evaluation of activated structures are required. The preparation process can be divided into dismantlement of existing facilities that interfere with the reactor dismantling work and construction of various facilities for the dismantlement process. Through process details, the work time, manpower, and location required for each process will be calculated. Radiation field evaluation takes into account changes in the shape of structures by process and calculates millions of areas by process, so integrated scripts are developed and utilized to integrate input text data. If the radiation field evaluation confirms that the radiation risk of workers is high, mutual feedback will be exchanged so that the process can be improved, such as the installation of temporary shields. The results of this study will be used as basic data for the final decommissioning plan for Wolsong unit 1. By reasonably estimating the dose of workers through computer analysis, safety will be the top priority when decommissioning.

We investigated the epidemiological characteristics of the antimicrobial resistant Enterococcus isolates from the four major rivers of Korea in 2012. A total 316 surface water samples were collected from three distinct sites (nearby livestock farms, tributaries, and major rivers) at two different seasons (dry season: n = 76, wet season: n = 240). A total 654 bacterial cells were isolated from samples and their genus distribution were determined. We found that Gram-negative bacteria including various genera were prevalent (n = 522, 79.8%), and Enterococcus was the most common genus of Gram-positive bacteria (n = 119, 18.2%). The isolation rate of Gram-negative bacteria was higher in wet season, whereas that of Enterococcus isolates was higher in dry season. The prevalence of Enterococcus isolates was also higher nearby livestock farms than on tributaries and main rivers. Since Enterococcus isolate is a key indicator for animal fecal contamination, the following experiments focused on this microorganism. As compared to a previous report in 2006, the resistance rates in E. faecium to erythromycin (40.0% to 69.9%) and chloramphenicol (0% to 16.4%) were increased, whereas those to penicillin (56.0% to 4.1%) and teicoplanin (36.0% to 0%) were decreased. We also found that antimicrobial-resistant (AMR) E. faecium isolates from rivers and livestock samples shared similar pulsed-filed gel electrophoresis (PFGE) profiles, validating the transmission of AMR Enterococcus isolates from livestock to river. Taken together, this study provides us with detailed information about bacterial contamination status in four major rivers, and highlights the changes in AMR pattern of Enterococcus isolates, which are expected to have originated from livestock.

This study was performed to assess the cosmic-ray effect caused by altitude in the aerial gammaray measurement. For the gamma-ray measurement experiment by altitude, the aerial survey system composed of four 4×4×16 inches large volume NaI (Tl) detectors was used. The aerial survey system was installed in a rotor-craft to stably keep its flight altitude and position. In addition, in order to avoid to time-dependent shielding effects with the amount of fuel, a rotor-craft of which the fuel tank is not located beneath the cabin floor was selected. In this study, the ROI (Region Of Interest) was set to the 3~6 MeV range to assess the cosmic-ray contribution to the gamma-ray spectrum that could ignore the contribution of the dominant natural radionuclides. The gamma-ray spectra measured inside and outside of the rotor-craft on the ground were compared to evaluate the shielding effects of the aircraft body. As a result, the count rate of the 40K photo peak was decreased by about 10% when measuring the inside compared to the outside. On the other hand, the total count rate of the 3~6 MeV region was decreased by about 0.7% under the same condition. Therefore, the aircraft body effect was insignificant in 3~6 MeV region considering the relative uncertainty of 0.04~0.78% (1σ). In addition, the count rate in the 3~6 MeV range according to altitude was evaluated to assess the cosmic-ray effect. In order to evaluate the change in the ROI count rate according to the altitude, the gamma-ray spectrum was measured in the range of 300~2,000 m above the sea to avoid the effect of terrestrial radiation. As a result, the relationship between altitude and count rate in the 3~6 MeV range showed a high correlation with the R2 value of 0.99, when the approximate equation was derived in the form of a quadratic polynomial. Also, the count rate of 3~6 MeV at 50~500 m above the ground was estimated using the correlation equation, and this value was compared with the measured count rate. As a result of comparing the average value of estimated count rate and measured count rate, the relative difference is less than 2%. Considering the relative uncertainty of 0.78~4.11% (1σ), it was possible to evaluate the count rate of the 3~6 MeV region relatively accurately. The results of this study could be used for further study on background dose corrections in aerial survey.

For safe management of spent nuclear fuels, they should be delivered to repository or waste disposal site. As the amount of spent nuclear fuel transportation is expected to increase in the future due to the provision of an intermediate storage facility, the necessity to secure transportation cask is emerging. In order to secure the spent nuclear fuel transportation cask, it is necessary to analyze the regulatory processes for domestic and foreign spent nuclear fuel transportation cask. In this study, the regulatory processes for domestic and foreign spent nuclear fuel transportation cask was analyzed. In this study, the IAEA, US, and Korea spent nuclear fuel transportation cask regulatory processes were analyzed. The domestic and foreign spent nuclear fuel transportation cask regulatory processes consist of design phase, manufacturing phase, and operation phase. In the design stage, the transport requirements are designed in accordance with the safety requirements of international organizations and countries. The application to be submitted when applying for approval should include a safety analysis report, evidence proving compliance with safety requirements et al. In the manufacturing stage, it is a stage to check whether the safety requirements are satisfied before the first use after manufacturing the transportation cask. Inspections include welding inspection, leakage inspection, shielding inspection, and thermal inspection. In the operation stage, it is a stage of periodically performing inspections for continuous maintenance of the package when the transportation cask is used. The inspection items to be performed are similar to the manufacturing stage and typically include performance inspection of components and leakage inspection. In this study, domestic and foreign spent nuclear fuel transportation cask regulatory processes were analyzed. It was found that the domestic and foreign spent nuclear fuel transportation cask regulatory processes consist of the design phase, the manufacturing phase, and the operation phase. The results of this study can be used as basic data for policy decision-making for the spent nuclear fuel cask.

One of the promising candidates for heat transfer fluid is molten chloride salts. They have been studied in various fields such as the electrolyte of pyroprocessing, the molten salt reactor coolant, and the energy storage system media. Main considerations for utilizing molten chloride salts are the compatibility of salts with structural materials. The corrosion behavior of structural materials in molten chloride salts must be understood to identify suitable materials against the corrosive environment. In this study, the corrosion behavior of a candidate structural material, Hastelloy N, in molten LiCl- KCl salt at 500°C were investigated by the electrochemical impedance spectroscopy (EIS) method. The sheet type of Hastelloy N was utilized as the working electrode in LiCl-KCl to measure the EIS data for 100 hours with 5 hours of time intervals. The EIS data were measured in the frequency range from 104 Hz to 10-2 Hz with the AC signal (amplitude = 20 mV) at open circuit potential. The capacitance semicircle observed in Nyquist plots for all periods indicates that charge-transfer controlled reactions occur. As the immersion time progresses, the radius of the semicircle in Nyquist plots and the impedance and phase angle in Bode plots decrease. These behaviors suggest a decreasing reaction resistance and the corrosion reactions are accelerated with the immersion time. The EIS data were fitted using the equivalent circuit to achieve quantitative results. Two capacitor-resistor components were considered due to the overlapped shape of two valleys in phase angle. The depressed shape of the semicircle in Nyquist plots led to the use of the constant phase element(Q) instead of the capacitor. Therefore, R(Q(R(QR))) circuit was selected to fit the EIS data. Fitting results show that the charge transfer resistance decreases dramatically within 1 day and then converges. The film resistance shows no clear trends, but the increase of the film admittance value indicates the decreased film thickness. Consequently, the film appears to exist like the oxide layer but it does not act as a protective layer. The real-time EIS data were measured in molten salt and provides the corrosion behavior over time. The corrosion mitigation strategy should consider that the corrosion of Hastelloy N accelerates over time and its intrinsic film cannot act as the protective layer. The next steps of this study are to evaluate other candidate structural materials and to demonstrate the presence of the film.