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        검색결과 4,138

        481.
        2022.05 구독 인증기관·개인회원 무료
        As the number of aging nuclear power plants increases, the market for dismantling nuclear power plants is growing rapidly. About 40% of the cost of dismantling nuclear power plants is the waste treatment cost incurred during the dismantling process, of which concrete waste accounts for a significant portion of the total waste. Securing technology for reducing and recycling concrete waste is very important not only in terms of economy but also in terms of environment. The objective is to synthesize geopolymer using inorganic materials from cement fine powder in concrete waste. Cement fine powder in concrete waste has a large amount of inorganic elements necessary for filing materials for radioactive waste treatment such as CaO and SiO2. In particular, Ca(OH)2 is synthesized by extracting Ca2+ from concrete waste. It can be used as an alkali activator to synthesize geopolymer. The mortar from crushed concrete was used as a source of calcium. The first step is to react with concrete waste and hydrochloric acid to extract ions. The second step is to react with NaOH and synthesize Ca(OH)2. The product was divided into two stages according to the reaction method and order. The first and second products were washed and dried, and then XRD and XRF were performed. The second product was matched only Ca(OH)2 and CaCO3 at the XRD peak. In the case of XRF, it was analyzed to have a purity of 67.80–78.73%. Synthesis of geopolymer by recycling materials extracted from concrete waste can reduce disposal costs and improve the utilization rate of disposal sites.
        482.
        2022.05 구독 인증기관·개인회원 무료
        In this work, we introduce a 100 kW class mobile plasma melting system designed for non-combustible radioactive wastes treatment. To ensure mobility, the designed system consists of two 24-ft commercial containers, each in charge of the plasma utilities and melting process. In the container for plasma utilities, a 100 kW class DC power supply is installed together with a chiller and gas supply system whereas the container for melting process has a transferred type arc melter as well as off-gas treatment system consisting of a heat exchanger, filtrations, scrubber and NOx removal system. As a heat source for a transferred type arc melter, we adopted a hollow electrode plasma torch with reverse polarity discharge structure. Detailed design for a 100 kW class mobile plasma melting system will be presented together with the main specifications of the components. In addition, the basic performance data of the melting system is also presented and discussed.
        483.
        2022.05 구독 인증기관·개인회원 무료
        Liquid scintillation cocktail is liquid waste, which consists of an organic solvent, scintillator, surfactant, and radionuclide. Large volumes of liquid scintillation waste are generated each year, and both the organic compound and radionuclide content can negatively affect on the health and the environment. Therefore, the liquid scintillation waste should be treated in an appropriate way. In this study, to facilitate the treatment of liquid scintillation waste, the sulfate-radical advanced oxidation process (SR-AOP) was performed for the mineralization of liquid scintillator waste. In SR-AOP, highly reactive sulfate radicals, which react more selectively and efficiently with organic compounds, are produced in situ by cleaving the peroxide bond in the persulfate molecule. For the experiment, 100 times diluted ULTIMA GOLD-LLT (initial TOC=699,800 ppm) was used as a liquid scintillation waste. The TOC removal efficiency of liquid scintillation waste by the OXONE (potassium peroxymonosulfate, PMS, 2KHSO5+KHSO4+K2SO4) and sodium persulfate (PS) with varying dosages (4–12 mM) was tested, and the effects of Co2+ and Cu2+ catalysts were compared at a range of pHs (3, 7, and 9). The experimental results demonstrated that 91% TOC removal of ULTIMA GOLD-LLT could be achieved for SR-AOP at initial pH=9, Co2+=1.2 mM (catalyst), PMS=4.8 mM (oxidant) for 60 min reaction. Compared to traditional Fenton AOP which is effective only at low pH, PMS based SR-AOP with Co2+ catalyst is effective at wide range of pHs and less dependent on the treatment efficiency of the operational pH. Therefore, it can be useful for the mineralization of liquid scintillation waste which is difficult to treat with a general treatment method due to the mixture of various organic compounds.
        484.
        2022.05 구독 인증기관·개인회원 무료
        Immobilization of radioactive borate waste containing a high boron concentration using cement waste form has been challenged because the soluble borate phase such as boric acid reacts with calcium compounds, hindering the hydration reaction in cement waste form. Metakaolin-based geopolymer waste form which has a pure aluminosilicate system without calcium can be a promising alternative for the cement; however, secondary B-O-Si networks are formed by a reaction between borate and silicate, resulting in poor mechanical characteristics such as low compressive strength and final setting retardation. Thus, it is important to optimize the Si/Al molar ratio and curing temperature which are critical parameters of geopolymer waste form to increase borate waste loading and enhance the durability of geopolymer. Here, metakaolin-based geopolymer waste form to immobilize simulant radioactive borate waste was fabricated by varying the Si/Al molar ratio and curing temperature. The 7 days-compressive strength results reveals that the Si/Al molar ratio of 1.4 and curing at 60°C is advantageous to achieving high waste loading (30wt%). In addition, geopolymer waste forms with the highest borate waste loading exceeded the 3.445 MPa after the waste form acceptance criteria such as thermal cycling, gamma irradiation, and water immersion tests. The leachability index of boron was 7.56 and the controlling leaching mechanism was diffusion. The thermal cycling and gamma irradiation did not significantly change the geopolymer structure. The physically incorporated borate waste was leached out from geopolymer waste form during leaching and water immersion tests. Considering these results, metakaolin-based geopolymer waste form with a low Si/Al ratio is a promising candidate for borate waste immobilization, which has been difficult using cement.
        485.
        2022.05 구독 인증기관·개인회원 무료
        Nuclear security event involving nuclear and other radioactive materials outside of regulatory control (MORC) has the potential to cause severe consequences for public health, the environment, the economy and society. Each state has a responsibility to develop national nuclear security measures including nuclear forensics to respond to such events. In Japan, national nuclear forensics capability building efforts mainly based on research and development (R&D) have been conducted since 2010, in accordance with national statement of Japan at the Nuclear Security Summit in Washington DC. Most of that work is undertaken at the Integrated Support Center for Nuclear Non-proliferation and Nuclear Security (ISCN) of the Japan Atmic Energy Agency (JAEA) in close cooperation with other competent authorities. The ISCN has made increased contributions to the enhancement of international nuclear security by establishing technical capabilities in nuclear forensics and sharing the achievements with the international community. The ISCN has mainly engaged in R&Ds for establishing and enhancing nuclear forensics technical capability. As for the laboratory capability, several new pieces of analytical equipment have been introduced for nuclear forensics R&D purposes. High-precise measurement techniques validated in the past nuclear forensics incidents have been established, and novel techniques that can contribute to the more timely and confident nuclear forensics signature analysis have been developed. The ISCN has been also developed a proto-type nuclear forensics library based on the data of nuclear materials possessed for past nuclear fuel cycle research in JAEA. These technical capability developments have been conducted based on the cooperation with international partners such as the U.S. Department of Energy and EC Joint Research Center, as well as participation in exercises organized by Nuclear Forensics International Technical Working Group (NF-ITWG). Recent R&D works have been mainly based on the needs of domestic competent authorities, such as first responders and investigators, and aim to develop technologies covering the entire spectrum of nuclear forensics processes from crime scene investigation to laboratory analysis and interpretation. One important key issue is the enhancement of technical capability for post-dispersion nuclear forensics. For instance, the ISCN has carried out the development of radiation measurement equipment coupled with the low-cost and mobile radiation detectors that uses machine-learning algorithms for quick and autonomous radioisotope identification to support first responders during crime scene investigations. Laboratory measurement techniques for samples collected at a post-dispersion crime scene are also among the important technical issues studied at the ISCN. The application of emerging technologies to nuclear forensics has also been studied. This includes the application of deep leaning models to nuclear forensics signature interpretation that could provide more confident results, as well as the development of contamination imaging technology that could contribute to the analytical planning on the samples in collaboration with conventional forensics. Many analytical techniques have been developed and the capability to analyze nuclear and other radioactive materials for nuclear forensics purposes has been considerably matured over the past decade. The challenges of post-dispersion samples, collaboration with conventional forensics and the development of novel signatures will be more important in the near future. Therefore, the ISCN will promote the R&Ds to further enhance the technical capabilities solving these issues. In addition, the ISCN is also promoting to expand the nuclear forensics research into universities and other research institutes in Japan. This is expected to contribute to the establishment of a domestic nuclear forensics network that enables to respond timely and flexibly to the MORC incidents, and to the maturation of nuclear forensics as a new academic field.
        487.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Along with the current rapid development of technology, object classification is being researched, developed, and applied to security systems, autonomous driving, and other applications. A common technique is to use vision cameras to collect data of objects in the surrounding environment. Along with many other methods, LiDAR sensors are being used to collect data in space to detect and classify objects. By using the LiDAR sensors, some disadvantages of image sensors with the negative influence on the image quality by weather and light condition will be covered. In this study, a volumetric image descriptor in 3D shape is developed to handle 3D object data in the urban environment obtained from LiDAR sensors, and convert it into image data before using deep learning algorithms in the process of object classification. The study showed the potential possibility of the proposal and its further application.
        4,000원
        488.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The bacterial soft-rot disease is one of the most critical diseases in vegetables such as Chinese cabbage. The researchers isolated two bacteria (Pseudomonas kribbensis and Pantoea vagans) from diseased tissue samples of Chinese cabbages and confirmed them as being the strains that cause soft-rot disease. Lactic-acid bacteria (LAB), were screened and used to control soft-rot disease bacteria. The researchers tested the treatments with hypochlorous acid water (HAW) and LAB supernatant to control soft-rot disease bacteria. The tests confirmed that treatments with the HAW (over 120 ppm) or LAB (Lactobacillus plantarum PL203) culture supernatants (0.5 mL) completely controlled both P. kribbensis and P. vagans.
        4,000원
        489.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        예술적 상황은 그것이 가져오는 이해가능성에 그 힘을 의존하며, 그런 이해가능성은 그 자체가 변형의 도구인 ‘정확하고’ 구체적인 양식을 통해 설명된다. 이와 관련하여 우리는 마힘바타(7세기 인도 이론가)와 아누마나와 관련된 그의 이론화 (추론)를 주목할 필요가 있다. 그에 따르면, 첫째, 자연 속에서 계속되는 모순되지 않 는 보편적 관계(vyapti)에 의해 객체와 주체가 함께 결합될 때, 이 둘은 변모한다. 둘 째, 마힘바타는 연역법칙에 의해 필요에 따라 일상적인 것에서 의미 있는 것으로 발전 한다는 사실을 고려할 때만 예술성이 보편화된다고 주장한다. 일상적인 것에서 의미 있는 것으로의 예술적 경험의 이 두 가지 탁월하게 빛나는 전제를 바탕으로 예술성의 동시성과 전시를 낳는 것이 가능해진다. 마힘바타의 추론 이론에서 발전된 개념적 구 조를 바탕으로 W. B. 예이츠와 T. S. 엘리엇의 시를 읽을 때 새로운 관점을 제공한 다. 예이츠의 시에서 육체와 영혼은 각각 작은 것과 큰 것이라는 의미를 내포하는 두 용어로 나타나며, 둘 다 퇴폐와 해방에 의해 결합되어 궁극적으로 보편적인 병존 (vyapti)을 하게 된다. 마찬가지로 엘리엇의 시에서 고통, 불임, 죽음은 육체와 관련되 는 용어이고 진리와 지식라는 용어는 영혼과 관련된다. 낮은 수준에 몸이 있고 높은 수준에 영혼의 내재가 있다. 하지만 그 사이에는 병존(모순되지 않은 보편적 경험)이 있는 반면 몸은 영혼으로 발전한다. 모든 사실은 필연적으로 마힘바타의 아누마나 (Anumana)에서 확립된 추론에 귀속된다.
        7,700원