본 연구는 대한민국 울릉도 특산식물인 추산쑥부쟁이(Aster × chusanensis Y.S.Lim, Hyun, Y.D.Kim & H.C.Shin)의 기내 대량증식체계 확립을 위해 시토키닌 계열 식물생장조절 제를 첨가하여 캘러스 및 신초 형성 조건을 구명하고자 수행 하였다. 실험결과, 추산쑥부쟁이의 줄기 절편체에서 캘러스 와 신초가 형성되었다. 캘러스 형성률은 TDZ 3.0mg·L-1처 리구에서 88.9%로 가장 높았고 BAP 3.0mg·L-1와 Zeatin 3.0mg·L-1 처리구는 66.7%, 2iP 3.0mg·L-1 처리구에서는 11.1%였다. 신초 형성률은 모든 처리구에서 77% 이상이고 특히 TDZ처리구와 Zeatin 처리구에서 100%였다. 그러나 TDZ처리구에서는 형성된 신초가 부풀어 오르거나, 잎에 과수 성이 나타나는 등 형태적 기형이 나타났다. Zeatin처리구에 서 발생한 신초는 정상적인 형태를 나타났다. 잎 절편체에서 는 캘러스, 신초가 발생하지 않았으며 절편체가 탈색하며 고 사하는 것을 확인하였다. 종합적으로 추산쑥부쟁이의 캘러 스 및 신초 형성을 위해서는 줄기 절편체를 배양 재료로 이 용하는 것이 효과적으로 확인되었다. 캘러스 유도에는 TDZ 3.0mg·L-1처리가 가장 효과적이었고, 추후 NAA와 같은 옥신 을 함께 첨가하여 증식 효과를 분석하는 연구가 필요할 것이 다. 또한, 신초 유도에도 TDZ 3.0mg·L-1 처리가 효과적이었 으나 장기간, 고농도로 사용할 경우 형태적인 기형이 발생할 수 있어 정상적인 식물생산에 부적합한 것으로 확인되었다. 따라서 형태적 기형이 발생하지 않은 아데닌 유도체형 시토키 닌인 Zeatin을 활용하는 것을 추천한다. 본 연구는 울릉도 특 산식물인 추산쑥부쟁이의 기내 대량증식과 생태계 유지에 필 요한 종 공급을 위한 대량증식 체계 구축을 위한 자료로 활용 할 수 있을 것이다.

Pasture formation and management are crucial to avoid yield reduction. This experiment aimed to examine the effects of tall fescue-centered mixed-seeding combinations on yield and vegetation changes in perennial pastures in the central region for two years, from September 2020 to October 2022. The treatments were arranged in three replications in a randomized block design: control (C), tall fescue-based mixture-1 (T-1), and tall fescue-based mixture-2 (T-2). The tall fescue (TF), orchard grass (OG), perennial ryegrass (PRG), Kentucky bluegrass (KBG), and white clover (WC) were used. The emergency rate of grasses (70.0 to 73.3%) did not differ among mixed seeding combinations. Overwintering rates (81.7 to 83.3%) were similar among treatments. The plant height of grasses was similar at each harvest date, with the highest height (86.2 cm) recorded in the second harvest of the first year, followed by that (58.4 cm) in the third harvest of the first year; it was least (38.9 cm) in the fourth harvest of the second year. There was no significant difference in the dry matter yield of grasses among the mixed seeding combination treatments in the first, third, or fourth harvests of the first year (p>0.05). For second-year grasses, dry matter yield was not significantly different in harvest date among the treatments (p>0.05). Based on mixed seeding ratio, orchard grass showed the highest yield at 70% in the C treatment, followed by tall fescue at 80% and 60% in the T-1 and T-2 treatments, respectively, in the first harvest after seeding. There was no significant difference in feed value between treatments (p>0.05), but a significant difference was observed between the third and fourth harvest (p<0.05). Therefore, it indicated that it is important to create perennial pastures in the central region through mixed seeding combinations centered on tall fescue.

KORAD (Korea Radioactive Waste Agency, http://www.korad.or.kr) has stored slightly contaminated ascon (asphalt coated concrete mixture) that was introduced to Gyeongju repository about a decade ago waiting for a final disposal. It is believed to be mainly contaminated by radioisotope 137Cs due to impurities introduced from the outside during the ascon manufacturing process. We studied characteristics of the radioactive waste to see whether this material would be proper enough to be disposed in Gyeongju LILW repository or be other ways to reduce the disposal volume including self-disposal before its final disposal otherwise. KORAD looked into the properness of characteristics of ascon in terms of WAC (Waste Acceptance Criteria) documented by KORAD that includes general chemical and physical properties of asphalt, density, size of grains, content of organic material and possibility of existence of chelate materials that qualitatively limited to be disposed by the criteria. And other associated characteristics such as gas generation and bio degradation were also investigated. Based on the data obtained from the study, we proposed various plausible solutions in associated with operational and disposal safety and economic view points. This study will be used for KORAD’s decision on how to control and safely dispose the spent ascon within a reasonable time period. And also those experiences may be applied for other LILW issues that require treatment or conditioning of radioactive wastes in the future.

This study aimed to develop a new eco-friendly control method of B. tabaci using a trap plant treated with systemic insecticide. Due to high preference, tobacco plant was selected as a trap plant among solanaceous plants. Out of all 6 systemic insecticides, dinotefuran WG showed the highest mortality (> 97.3 %) against B. tabaci. The concentrations of dinotefuran in tobacco leaves after systemic treatment showed the sharp increase in the pesticide from 2 hrs until 48 hrs (2 d) and steady increase over 35 d. The mortality of B. tabaci in tobacco leaves was about 80% at 9 hrs after treatment and over 90% at 1, 2, 3, 6, 9, and 35 d after treatment. The number of B. tabaci was counted every week after dinotefuran-treated tobacco pots were placed in the tomato greenhouse cultivation. The density of the insects with 3 tobacco plants was app. 75% lower than the control (w/o tobacco plant).

강원특별자치도 18개 시군을 대상으로 감나무와 콩에 발생하는 미국선녀벌레, 썩덩나무노린재, 담배거세미 나방의 발생을 조사하였다. 돌발해충인 미국선녀벌레는 약충기인 6월과 성충기인 10월에 발생조사를 진행하고 남방계해충인 담배거세미나방과 썩덩나무노린재는 7월과 9월 콩 재배기에 발생조사를 진행하였다. 미국선녀 벌레는 강원지역에 있는 감나무에서 발생을 확인할 수 없었고. 감나무 주변 기타 수목에서 가지당 평균 6.7마리 발생하였다. 담배거세미나방은 7월, 속초를 제외한 모든 시군에서 발생이 되었으며, 춘천, 횡성에서 트랩당 60마 리가 넘는 발생밀도를 보였으며, 원주, 강릉, 화천 등 에서는 트랩당 1마리로 낮은 발생밀도를 나타냈다. 썩덩나무 노린재는 7월 춘천, 속초, 홍천 등 7개 시군을 제외한 11개 시군에서 트랩에 포획되는 것을 확인하였으며, 화천에 서 트랩당 26마리로 최고발생밀도를 보였다.

Some consumer goods containing radioactive substances are in circulation and used in everyday life. In accordance with the Nuclear Safety Act, consumer goods with radioactivity are regulated. However, since most consumer goods distributed in Korea have no information that can confirm the amount of radiation, it is necessary to analyze the radiation for safety regulation. Among these consumer goods, GTLS (Gaseous Tritium Light Source) contains gaseous tritium (tritium, written as 3H or T), which is a radioactive material. The gaseous composition ratio in GTLS was analyzed using a precision gas mass spectrometer (Thermo Fisher, model MAT 271). As a result of GTLS analysis, the H2, HD or H3 +(T) or 3He, HT or D2 or He, DT, and T2, which correspond to the mass-to-charge ratio (m/z) 2 to 6 and the air components were detected. In addition, substances corresponding to m/z=24 and m/z=21 were also detected. These were compared with pure CH4 and those fragmentation patterns. The ratios of CT4 (m/z = 24) to CT3 (m/z = 21) and CH4 (m/z = 16) to CH3 (m/z = 15) were compared and they agree within the measurement uncertainty. We also performed additional experiments to separate the water component in the GTLS samples, considering the possibility that the m/z = 21 to m/z = 24 region is tritium compounds based on H2O. Despite the removal of the water components, peaks were detected at m/z=21 and m/z=24. Therefore, we confirmed that the component of m/z = 24 in the GTLS sample was CT4.

The mobility of radionuclides is largely determined by their radiological properties, geochemical conditions, and adsorption reactions, such as surface adsorption, chemical precipitation, and ion exchange. To evaluate the safety assessments of radionuclides in nuclear sites, it is essential to understand the behavior and mechanism of radionuclides onto soils. Since nuclear power plants are located in coastal areas, the chemical composition of groundwater can vary depending on the intrusion of seawater, altering the adsorption distribution coefficient (Kd) values of radionuclides. This study examines the impact of seawater on the Kd values of clay minerals for cesium (Cs) and strontium (Sr). The results of Cs+ adsorption experiments showed a broad range of Kd values from 36 to 1,820 mL/g at an initial concentration of 1 mg/L and a high sorption coefficient of 15-613 mL/g at an initial concentration of 10 mg/L. Montmorillonite, hydrobiotite, illite, and kaolinite were ranked in terms of their CEC values for Cs+ adsorption, with hydrobiotite having the highest adsorption at 1 mg/L. The results of Sr adsorption experiments showed a wide range of Kd values from 82 to 1,209 mL/g at an initial concentration of 1 mg/L and a lower adsorption coefficient of 6.68-344 mL/g at an initial concentration of 10 mg/L. Both Cs+ and Sr2+ demonstrated lower Kd values at higher initial concentrations. CEC of clays found to have a significant impact on Sr2+ Kd values. Ca2+ ions showed a significant impact on Sr2+ adsorption distribution coefficients, demonstrating the greater impact of seawater on Sr2+ compared to Cs+. These findings can inform future safety assessments of radionuclides in nuclear sites.

After the Fukushima accident, significant amount of radioactively contaminated waste has been generated with 50~250 m3/day and stored in tanks of the Fukushima Daiichi nuclear power plant site. The contaminated water is treated by various treatment facility such as KURION, SARRY, Reverse Osmosis, and ALPS to remove 62 radioactive nuclides except H-3. For the contaminated water treatment process, massive secondary wastes such as sludge, spent adsorbent, and so on as by-product are being generated by the facilities. In Japan, to treat the secondary wastes, melting technologies such as GeoMelt, In-can vitrification and Cold Crucible Induction Melting vitrification are considered as a candidate technologies. In this study, the technologies were reviewed, and the advantage and disadvantage of each technology were evaluated as the candidate technologies for treatment of the secondary wastes.

Plasma torch melting has been considered as a promising treatment technology for radioactive waste generated by nuclear power plants. The IAEA reported in 2006, the plasma melting technology could be treated regardless of the type of radioactive wastes such as combustible, non-combustible and liquid. Also, the technology has the advantage of being an eco-friendly technology. It emits less harmful gases such as NOx, SOx, HCl and CO because it does not use fossil fuels. In KHNP CRI, the plasma torch melting system was developed as the new radioactive waste treatment technology. In this study, to evaluate the long-term integrity of the new facility, a demonstration test with concrete as a simulant was carried out for about 3 days. For the 3 days, the evaluation was conducted in view of abnormal shutdown, soundness of waste feeding device, electrode consumption, and so on.

In KHNP CRI, the PTMs (plasma torch melting system) was developed as a treatment technology of a wide variety of radioactive wastes generated by nuclear power plants. The facility is made of melting zone, thermal decomposition zone, melt discharge zone, waste feeding device, MMI, and offgas treatment system. In this study, demonstration test was conducted using NaOH solution as liquid waste to evaluation the applicability of the PTM system. For demonstration test of NaOH solution treatment, the plasma melting zone is sufficiently pre-heated by the plasma torch for 5 hours. The temperature inside the plasma melting zone is about 1,600°C. The NaOH solution as simulant was put into the thermal decomposition zone by the spray feeding device with the throughput of maximum 30 liter/hour. During the test, the power of plasma torch is about 100 kW on the transferred mode. The 160 liters of liquid waste was treated for 500 minutes. After the demonstration test, the final product in the form of salt was remained in the melting zone, and the disposal of the final product are still under consideration.

The stabilization techniques are highly required for damaged nuclear fuel to strengthen safety in terms of transportation, storage, and disposal. This technique includes recovering fuel materials from spent fuel, fabrication of stabilized pellets, and fabrication of fuel rods. Thus, it is important to identify the leaching behavior of the stabilized pellets to verify their stability in humid environments which are similar to storage conditions. In this study, we introduce various leaching experiment methods to evaluate the leaching behavior of the stabilized pellets, and determine the most suitable leaching test methods for the pellets. Also, we establish the leaching test conditions with various factors that can affect the dissolution and leaching behavior of the stabilized pellets. Accordingly, we prepare the simulated high- (55 GWd/tU) and low- (35 GWd/tU) burnup nuclear fuel (SIMFUEL) and pure UO2 pellets sintered at 1,550°C and 1,700°C, respectively. Each pellet is placed in a vessel and filled with DI water and perform the leaching test at three different temperature to verify the leaching mechanism at different temperature range. Based on the standard leaching test method (ASTM C1308-21), the test solution is removed from the pellet after specific time intervals and replaced in the fresh water, and the vessel is placed back into the controlled-temperature ovens. The test solutions are analyzed by using ICP-MS.

When damaged nuclear fuel is stripped and re-fabricated into stabilized pellets, it is necessary to analyze the characteristics of the stabilized pellets, such as density, leaching behavior, and compressive strength, for final disposal. In this study, simulated nuclear fuel with UO2 and burn-up of 35 GWd/tU and 55 GWd/tU was used to measure the compressive strength of the stabilization pellet. In order to change the density of the sintered pellet, a sintered pellet was prepared by heat treatment at 1,550°C and 1,700°C for 6 hours in a reducing atmosphere of 4% H2/Ar. In the case of UO2, the density was 10.4 g/cm3 (94.5% of T.D.) and 10.6 g/cm3 (96.6% of T.D.) depending on the sintering temperature (1,550°C, 1,700°C). In the case of simulated fuel with a burn-up of 35 GWd/tU, the density was 8.8 g/cm3 (80.9% of T.D.) and 10.2 g/cm3 (93.6% of T.D.) depending on the sintering temperature (1,550°C, 1,700°C). In the case of simulated fuel with a burn-up of 55 GWd/tU, the density was 8.3 g/cm3 (77.0% of T.D.) and 10.0 g/cm3 (92.3% of T.D.) depending on the sintering temperature (1,550°C, 1,700°C). It was found that the compressive strength of simulated nuclear fuel decreased with increasing burn-up and increased with increasing density. In the case of UO2, the compressive strengths were 717.8 MPa and 897.4 MPa when the densities were 10.4 g/cm3 and 10.6 g.cm3, respectively. In the case of simulated nuclear fuel with a burn-up of 35 GWd/tU, the compressive strengths were 472.1 MPa and 732.3 MPa when the densities were 8.8 g/cm3 and 10.2 g/cm3. In the case of simulated nuclear fuel with a burn-up of 55 GWd/tU, the compressive strengths were 301.4 MPa and 515.5 MPa when the densities were 8.3 g/cm3 and 10.0 g/cm3, respectively.

To investigate the effect of the catalyst and metal–support interaction on the methane decomposition behavior and physical properties of the produced carbon, catalytic decomposition of methane (CDM) was studied using Ni/SiO2 catalysts with different metal–support interactions (synthesized based on the presence or absence of urea). During catalyst synthesis, the addition of urea led to uniform and stable precipitation of the Ni metal precursor on the SiO2 support to produce Ni-phyllosilicates that enhanced the metal–support interaction. The resulting catalyst upon reduction showed the formation of uniform Ni0 particles (< 10 nm) that were smaller than those of a catalyst prepared using a conventional impregnation method (~ 80 nm). The growth mechanisms of methane-decomposition-derived carbon nanotubes was base growth or tip growth according to the metal–support interaction of the catalysts synthesized with and without urea, respectively. As a result, the catalyst with Ni-phyllosilicates resulting from the addition of urea induced highly dispersed and strongly interacting Ni0 active sites and produced carbon nanotubes with a small and uniform diameter via the base-growth mechanism. Considering the results, such a Ni-phyllosilicate-based catalyst are expected to be suitable for industrial base grown carbon nanotube production and application since as-synthesized carbon nanotubes can be easily harvested and the catalyst can be regenerated without being consumed during carbon nanotube extraction process.

Thermal management is significant to maintain the reliability and durability of electronic devices. Heat can be dissipated using thermal interface materials (TIMs) comprised of thermally conductive polymers and fillers. Furthermore, it is important to enhance the thermal conductivity of TIMs through the formation of a heat transfer pathway. This paper reports a polymer composite containing vertically aligned electrochemically exfoliated graphite (EEG). We modify the EEG via edge selective oxidation to decorate the surface with iron oxides and enhance the dispersibility of EEG in polymer resin. During the heat treatment and curing process, a magnetic field is applied to the polymer composites to align the iron oxide decorated EEG. The resulting polymer composite containing 25 wt% of filler has a remarkable thermal conductivity of 1.10 W m− 1 K− 1 after magnetic orientation. These results demonstrate that TIM can be designed with a small amount of filler by magnetic alignment to form an efficient heat transfer pathway.