이산화탄소 배출이 없는 고분자 전해질 막 연료전지(polymer electrolyte membrane fuel cell, PEMFC)는 수송용, 발전용 시스템에 적용 가능한 친환경 에너지 변환장치이다. PEMFC의 주요 구성품 중 하나인 고분자 전해질 막(polymer electrolyte membrane, PEM)은 구동시간 동안의 높은 수소 이온 전도도와 물리화학적 안정성 갖춘 과불소화계 고분자 (perfluorinated sulfonic acid, PFSA) 기반 PEM (PFSA-PEM)이 상용화 되어있다. 하지만 PFSA-PEM의 단점으로 지적되는 낮은 유리전이온도와 높은 기체 투과도의 보완이 요구되고 있다. 이에 본 총설에서는 PFSA-PEM의 성능 향상 및 단점 보완 을 위해 1) PFSA의 측쇄부 길이를 조절함으로써 이온교환용량의 증가와 고분자의 결정성을 증가시켜 PFSA-PEM의 능력을 향상시킨 연구와 2) 유/무기 첨가제를 도입하여 수소 이온 전도도 및 물리적 안정성을 향상시키는 복합 막 연구 및 3) 다공성 지지체를 도입하여 PEM의 두께를 효과적으로 감소시켜 막 저항을 효과적으로 줄이고 내구성을 큰 폭으로 개선한 다공-충진 막에 관한 연구를 소개하고자 한다.

High Integrity Container (HIC) made of polymer concrete was developed for the efficient treatment and safe disposal of radioactive spent resin and concentrate waste in consideration of the disposal requirements of domestic disposal sites. Permission for application of Polymer Concrete High Integrity Container (PC-HIC) to the domestic nuclear power plants (NPPs) has been completed or is under examination by the regulatory agency. In the case of 860 L PC-HIC for very-low-level-waste (VLLW) or low low-level-waste (LLW), the application of four representative NPPs has been approved, and the license for extended application to the rest NPPs is also almost completed. A licensing review is also underway to apply 510 L PC-HIC for intermediate and low-level-waste (ILLW) to representative nuclear power plants. In order to handle and efficiently store and manage PC-HICs and high-dose PCHIC packages, a gripper device that can be remotely operated and has excellent safety is essential, and the introduction of NPPs is urgent. The conventional gripper device developed by the PC-HIC manufacturer for lifting test to evaluate the structural integrity of PC-HIC requires a rather wide storage interval due to its design features, and does not have a passive safety design to handle heavy materials safely. In addition, work convenience needs to be reinforced for safety management of high radiation work. Therefore, we developed a conceptual design for a gripper device with a new concept to minimize the work space by reflecting on-site opinions on the handling and storage management conditions of radioactive waste in NPPs, and to enhances work safety with the passive safety design by the weight of the package and the function of checking the normal seating of the device and the normal operation of the grip by the detector/indicator, and to greatly improves the work efficiency and convenience with the wireless power supply function by rechargeable battery and the remote control function by camera and wireless monitoring & control system. Through design review by experts in mechanical system, power supply and instrumentation & control fields and further investigations on the usage conditions of PC-HICs, it is planned to facilitate preparations for the application of PC-HIC to domestic NPPs by securing the technical basis for a gripper device that can be used safely and efficiently and seeking ways to introduce it in a timely manner.

대용량 화학 및 청정에너지의 운반체인 수소는 석유화학 산업 및 연료전지 등에서 많이 활용되는 중요한 산업용 기체이다. 특히 수소는 주로 증기개질 및 가스화를 통해 화석 연료에서 생성되며 부산물로 이산화탄소가 발생한다. 따라서 고 순도 수소를 얻기 위해서는 이산화탄소를 제거해야 한다. 본 총설에서는 배러 단위[1 Barrer = 10−10 cm3 (STP) × cm / (cm2 × s × cmHg)]로 보고된 이산화탄소로부터 수소를 분리하는 프리스탠딩 고분자 분리막 및 혼합매질 분리막에 초점을 맞추었 다. 최근 보고된 다양한 논문들을 분석하여 분리막의 구조, 형태, 상호 작용 및 제조 방법에 대해 논의하고 구조-물성 관계를 이해하여 향후 더 나은 분리막 소재를 찾는 데 도움이 되고자 한다. 다양한 분리막의 성능 및 특성 검토를 통해 수소/이산화 탄소 분리에 대한 Robeson 성능 한계선을 제시하고, 가교, 혼합 및 열처리 등의 기술을 사용하여 분리 특성을 개선하는 다양 한 혼합매질 분리막에 대해 논의하였다.

국제해사기구(IMO)는 국제해운 분야의 온실가스(Green House Gas, GHG) 감축을 위하여 각국의 기술 개발 및 에너지 효율성 제 고에 관한 정책 시행을 적극적으로 권장하고 있다. 이러한 IMO의 환경규제와 관련된 정책들은 해운 분야 전반에 큰 영향을 미치고 있으 며, 선주들에게도 막대한 부담으로 작용하고 있다. 선박에서 발생하는 GHG 배출을 억제하기 위한 가장 합리적인 방안은 탄소제로배출 (Zero Emission) 선박의 개발로 귀결된다. 즉 친환경 연료로 추진하는 연료전지선박(Fuel Cell Ship, FCS)의 개발이 IMO의 규제를 벗어날 수 있는 대안인 것이다. 아시아, 북미, 유럽 등의 각국에서는 독자적으로 PEMFC를 개발 및 생산하여 국제공인등록 기관으로부터 형식승인 인증을 획득함으로써 국제표준화의 선점을 추구하고 있다. 현재 다양한 연료전지(Fuel Cell, FC) 중에서 선박용으로 권장하는 것은 크게 고 분자전해질 연료전지(PEMFC), 용융 탄산염 연료전지(MCFC) 및 고체산화물형 연료전지(SOFC) 등의 세종류가 있다. 본 연구에서는 글로벌 FC 시장에서 지속적인 성장이 예상되는 PEMFC를 대상으로 하여 국내외 개발 동향, 제조업체별 규격, 성능 및 선박에 적용한 실증적 사례 를 분석하였다. 그리고 PEMFC를 선박에 적용할 경우, 고려해야 할 사항과 개발 방향에 관하여 제안하고자 하였다.

Rapid development of carbon nanotubes (CNTs) reinforced to polymer composites has been recently noticed in many aspects. In this work, the latest developments on fatigue and fracture enhancement of polymer composites with CNTs reinforcement with diverse methods are thoroughly compiled and systematically reviewed. The existing available researches clearly demonstrate that fatigue fracture resistance of polymer composites can be improved accordingly with the addition of CNTs. However, this work identifies an interesting research gap for the first time in this field. Based on the systematic reviewing approach, it is noticed that all previously performed experiments in this field were mostly focused upon studying one factor only at a time. In addition, it is also addressed that there were no previous studies reported a relationship or effect of one factor upon others during examining the fatigue fracture of carbon nanotubes. Moreover, there was no adequate discussion demonstrating the interaction of parameters or the influence of one parameter upon another when both were examined simultaneously. It is also realized that the scope of the conducted fatigue fracture studies of carbon nanotubes were mainly focused on microscale fatigue analysis but not the macroscale one, which can consider the effect of environment and service condition. In addition, the inadequacy of fatigue life predicting models via analytical and numerical methods for CNT-reinforced polymer composites have also been highlighted. Besides, barriers and challenges for future directions on the application of CNT-reinforced polymer composite materials are also discussed here in details.

This article presents recent advancements in the development of flexible piezoresistive strain sensors based on carbon nanotubes (CNTs)–polymer composites, with particular attention to their electromechanical properties. Various fabrication approaches and material preparation of CNTs–polymer composites with improved piezoresistive performance are introduced. Moreover, the article presents the working principle of the piezoresistive sensors in terms of the tunneling effect and disconnection-reconnection mechanism. The sensing performances of recently reported applications are studied. This work also reveals that the CNTs–polymer composites have great potential for flexible, skin-mountable, and wearable electronics applications. Finally, possible challenges for the future developments of CNTs–polymer composites are discussed.

During the normal operation boron concentrates and spent resins are generated. The boron concentrates are treated by concentrated waste drying system (CWDS) and results in fine powder form. The solidification or application of high integrity container (HIC) is required for the disposal of the dried boron concentrates. The spent resin is stored in storage tank after the water treatment. The spent resin also requires solidification or application of HIC to satisfy the waste acceptance criteria (WAC) in Korea. The solidification process requires periodic validation. The repeated validation and complicated process hesitates the practical application. The application of HIC offers various advantages, including flexible free standing water requirement, higher waste loading compared to solidification, and simple process. The polymer concrete (PC), which is a primary component for PC-HIC exhibits good material stability. The expected transportation mechanism of nuclide in the PC-HIC are 1) diffusion by concentration, 2) permeation by pressure, and 3) capillary suction when considering the disposal condition. Since the PC-HIC effectively prevents the intrusion of neighboring water and volume of free standing water is lower than 1%, it seems that diffusion by concentration is the primary transportation mechanism. In this study, the property of PC is investigated based on Cl ion diffusion test to evaluate the material reliability. The results indicate that PC exhibits superior stability compared to ordinary portland cement. In addition, the reliable life time of PC is estimated base on the element transportation phenomena.

The Korea Nuclear Safety Act defines a high integrity container (HIC) as “a radioactive waste packaging container that can maintain its integrity for more than 300 years under the general underground environment and disposal conditions in Korea”, and detailed technical standards are not described. The US Nuclear Safety Commission’s “Low-Level Waste Licensing Branch Technical Position on Waste Form” describes the detailed requirements for solidification and HIC. The main contents of the US NRC technical position include limiting the free standing water, minimum design life, demonstrating mechanical, thermal and radiation stability, etc. In this study, the stability evaluation was performed to understand the mechanical strength with respect to horizontal and vertical loads. The basic property of polymer concrete was carefully evaluated, including compressive strength, structural fatigue resistance, etc. The long term creep test, loading of 40% of compressive strength, indicates that the polymer concrete exhibits good long term mechanical integrity.

Radioactive materials emitted from nuclear accident or decommissioning cause soil contamination over wide areas. In the event of such a wide area of contaminated soil, decontamination is inevitable for residents to reside and reuse as industrial land. There are many ways to decontaminate these contaminated soils, but in urgent situations, the soil washing, which has a short process period and relatively high decontamination efficiency, is considered the most suitable. However, the soil washing process of removing fine soil and cesium by using washing liquid as water and adding a flocculating agent (J-AF) generates slurry/sludge-type secondary waste (Cs-contaminated soil + flocculating agent). Since this form of sludge contaminants cannot be disposed, solidification is needed using an appropriate solidification agent to treat wastes for disposal. Therefore, this study devised a treatment method of contaminated fine soils occurring after the soil washing process. This investigation prepared the simulated wastes of contaminated fine soils generated after the soil washing, and pelletized the samples using a roll compactor under the optimum operating conditions. The optimum conditions of the device were determined in the pre-test. Roll speed, feeding rate, and hydraulic pressure were 1.5 rpm, 25 rpm, and 28.44 MPa, respectively. The waste forms were manufactured by incorporating created pellets (H 6.5 × W 9.4 mm) using polymers as solidification agents. Used polymers were main ingredient (YD-128), hardener (G-1034), and diluent (LGE). The optimum mixing ratio was YD-128 : G-1034 = 65 : 35 phr, and LGE was added in an amount of 10wt% of the total mixture. To confirm the disposal suitability of the manufactured waste forms, characterization evaluation was carried out (compressive strength, thermal cycling, immersion, and leaching test). Characterization evaluation revealed a minimum compressive strength of 23.1 MPa, far exceeding 3.44 MPa of the disposal facility waste acceptance criteria. Compressive strength increased to the highest value of 31.90 MPa after immersion test. To examine leaching characteristics, the pH, Electrical Conductivity (EC) and leachability index (􀜮􀯜) of leachates were identified. As results, pH and EC consistently increased or remained constant with leaching time. The average of Co, Cs and Sr nuclides was 17.76, 17.38 and 14.04, respectively, exceeding the value of 6 in the waste acceptance criteria. Effective waste treatment/ disposal can be achieved without increasing volumes of sludge/slurry by enhancing the technique of this research by performing additional studies in the future.