• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2315-2324
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• 2023

Space nuclear reactors are becoming popular in deep space exploration owing to their advantages of high-power density and stability. Following the fourth-generation nuclear reactor technology, a conceptual design of the dual drum-controlled space molten salt reactor (D²-SMSR) is proposed. The reactor concept uses molten salt as fuel and heat pipes for cooling. A new reactivity control strategy that combines control drums and safety drums was adopted. Critical physical characteristics such as neutron energy spectrum, neutron flux distribution, power distribution and burnup depth were calculated. Flow and heat transfer characteristics such as natural convection, velocity and temperature distribution of the D²-SMSR under low gravity conditions were analyzed. The reactivity control effect of the dual-drums strategy was evaluated. Results showed that the D²-SMSR with a fast spectrum could operate for 10 years at the full power of 40 kWth. The D²-SMSR has a high heat transfer coefficient between molten salt and heat pipe, which means that the core has a good heat-exchange performance. The new reactivity control strategy can achieve shutdown with one safety drum or three control drums, ensuring high-security standards. The present study can provide a theoretical reference for the design of space nuclear reactors.

• 방사성폐기물학회지
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• 제20권3호
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• pp.365-369
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• 2022

Operating and decommissioning nuclear power plants generates radioactive waste. This radioactive waste can be categorized into several different levels, for example, low, intermediate, and high, according to the regulations. Currently, low and intermediate-level waste are stored in conventional 200-liter drums to be disposed. However, in Korea, the disposal of intermediate-level radioactive waste is virtually impossible as there are no available facilities. Furthermore, large-sized intermediate-level radioactive waste, such as reactor internals from decommissioning, need to be segmented into smaller sizes so they can be adequately stored in the conventional drums. This segmentation process requires additional costs and also produces secondary waste. Therefore, this paper suggests repurposing the no-longer-used spent nuclear fuel casks. The casks are larger in size than the conventional drums, thus requiring less segmentation of waste. Furthermore, the safety requirements of the spent nuclear fuel casks are severer than those of the drums. Hence, repurposed spent nuclear fuel casks could better address potential risks such as dropping, submerging, or a fire. In addition, the spent nuclear fuel casks need to be disposed in compliance with the regulations for low level radioactive waste. This cost may be avoided by repurposing the casks.

• 방사성폐기물학회지
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• 제6권1호
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• pp.45-54
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• 2008

경주 방폐장은 궁극적으로 80만 드럼의 폐기물을 수용하는 처분시설이다. 대부분 국외 처분시설의 경우도 정확히 완충의 의미가 아니더라도 관리의 정도를 차별하기 위하여 구역을 나누어 관리하는 것이 일반적이다. 국내 처분시설에서의 완충공간 설정에 대한 규제요건은 운영 중에는 원자력발전소와 크게 다르지 않아 운영중 정상운영 및 사고시 처분시설 제한구역 경계에서의 설계목표치나 성능목표치의 만족여부가 가장 주요한 요건이 된다. 폐쇄 후에의 완충공간의 의미는 제도적 관리기간 중에 부주의한 침입자가 침입하는 행위를 방지하는 최소한의 영역으로 설정될 수 있다. 부주의한 침입행위 중 직접적으로 피폭을 유발할 가능성이 가장 높은 우물이용 시나리오에 대한 안전성 평가결과가 운영중 평가결과를 바탕으로 설정된 완충공간에 적용하여도 충분히 성능목표치 만족함을 보임으로써 적합성을 확인한다. 현재 본격적인 건설을 앞둔 경주 처분시설의 완충공간 설정에도 동일한 절차와 개념이 적용되었고 규제요건과 방사선방어적으로 만족하는 구간이 설정되었다. 단, 처분시설의 활용면적은 향후 수십년간 점차로 증가하면서 그 형태가 변하게 될 것이다. 처분시설의 처분방식이나 처분용량이 달라지게 되면 10만 드림의 처분을 기준으로 설정한 제한구역이나 완충공간은 향후 변동될 것이 확실함에 따라 이에 대한 고려도 추후 반드시 필요하다.

• 자원리싸이클링
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• 제18권5호
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• pp.63-71
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• 2009

재활용선별시설에서 파봉공정은 연계된 선별공정을 위한 필수 공정으로 주로 인력에 의한 작업과 일부 기계식 파봉장치가 도입되었다. 그러나, 기계식 파봉장치의 경우 재활용 대상폐기물을 파쇄하여 선별효율의 저하 및 폭발 등 작업자의 안전문제가 자주 발생하고 있다. 본 연구에서는 기존 파봉 방식의 문제점을 해결 할 수 있는 회전칼날팔각드럼식 파봉 정량공급 장치를 개발하여 성능평가 및 환경성 검토를 통한 현장 적용 가능성 평가를 수행하였다. 실험결과에 의하면 처리용량은 드럼회전수 8.2 rpm, 벨트컨베이어 속도 1.25 m/min에서 5.6 ton/hr로 설계용량인 5.0 ton/hr를 만족하였으며, 최대 처리용량은 8.8 ton/hr으로 나타났다. 봉투 속 봉투의 파봉효율은 95.6% 및 겉봉투의 경우에는 100%로 나타났으며, 특히 재활용대상폐기물 중 가장 쉽게 파손되는 유리병의 원형보존율은 약 96.5%로 정가되었다. 본 장치의 소음, 진동 및 비산먼지 농도 등에 대한 환경성 정토결과 환경오염배출허용 법적기준치를 모두 만족하는 것으로 조사되었다. 따라서, 본 파봉장치를 재활용선별시설에 적용할 경우 기존의 인력파봉과 기계식파봉에서 발생되었던 문제점을 크게 개선할 수 있다.

• 방사성폐기물학회지
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• 제20권4호
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• pp.511-521
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• 2022

Decommissioning of nuclear power plants generates a large amount of radioactive waste in a short period. Moreover, Radioactive waste has various forms including a large volumes of metal, concrete, and solid waste. The disposal of decommissioning waste using 200 L drums is inefficient in terms of economics, work efficiency, and radiation safety. Therefore, The Korea Radioactive Waste Agency is developing large containers for the packaging, transportation, and disposal of decommissioning waste. Assessing disposability considering the characteristics of the radioactive waste and facility, convenience of operation, and safety of workers is necessary. In this study, the exposure dose rate of workers during the disposal of new containers was evaluated using Monte Carlo N-Particle Transport code. Six normal and four abnormal scenarios were derived for the assessment of the dose rate in a near surface disposal facility operation. The results showed that the calculated dose rates in all normal scenarios were lower than the direct exposure dose limitation of workers in the safety analysis report. In abnormal scenarios, the work hours with dose rates below 20 mSv·y^-1 were calculated. The results of this study will be useful in establishing the optimal radiation work conditions.

• 한국산업융합학회 논문집
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• 제26권4_1호
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• pp.545-551
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• 2023

In this paper, a robot automation methodology for chemical drum assembly in semiconductor industries are presented. Robot automation is essential to resolve safety issues in which operators are directly or indirectly exposed to chemicals or fumes in assembling dispense heads on chemical drums. However, the chemical drum assembling process involves complex and difficult tasks, such as mating male/female keycodes and fastening screws with large-diameter, which may be very difficult to be performed by a single-arm robot with a commercial rigid F/T sensor. In order to solve the problems, a method for assembling a chemical drum using dual-arm collaborative robot system, compliance F/T sensor, robot vision and gripper is presented.

• 한국산업융합학회 논문집
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• 제27권1호
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• pp.71-76
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• 2024

Automatic production systems are constantly advancing technologies to improve productivity and safety. Specifically, liquid filling machines are primarily utilized to package products into drums after manufacturing process in the hazardous chemical industry. Most existing filling machines allow the operator to open the drum cap and inject the product directly or semi-automation. In this study, we have developed a cap opening and closing mechanism onto the existing drum filling machine, enabling automatic and safe cap manipulation while filling the product in the IBC tank. By applying the appropriate torque value through numerical analysis, we confirmed that the system worked without any problems during the process of opening and closing the cap. Therefore, it is expected that the developed machine will give more production and reduce human efforts without risk in the chemical packaging industry.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1368-1375
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• 2016

A radiological safety assessment study was performed for the transportation of low level radioactive wastes which are temporarily stored in Korea Atomic Energy Research Institute (KAERI), Daejeon, Korea. We considered two kinds of wastes: (1) operation wastes generated from the routine operation of facilities; and (2) decommissioning wastes generated from the decommissioning of a research reactor in KAERI. The important part of the radiological safety assessment is related to the exposure dose assessment for the incidentfree (normal) transportation of wastes, i.e., the radiation exposure of transport personnel, radiation workers for loading and unloading of radioactive waste drums, and the general public. The effective doses were estimated based on the detailed information on the transportation plan and on the radiological characteristics of waste packages. We also estimated radiological risks and the effective doses for the general public resulting from accidents such as an impact and a fire caused by the impact during the transportation. According to the results, the effective doses for transport personnel, radiation workers, and the general public are far below the regulatory limits. Therefore, we can secure safety from the viewpoint of radiological safety for all situations during the transportation of radioactive wastes which have been stored temporarily in KAERI.

• 방사성폐기물학회지
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• 제21권2호
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• pp.255-269
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• 2023

Compared to operational wastes, nuclear power plant (NPP) decommissioning wastes are generated in larger quantities within a short time and include diverse types with a wider range of radiation characteristics. Currently used 200 L drums and IP-2 type transport containers are inefficient and restrictive in packaging and transporting decommissioning wastes. Therefore, new packaging and transport containers with greater size, loading weight, and shielding performance have been developed. When transporting radioactive materials, radiological safety should be assessed by reflecting parameters such as the type and quantity of the package, transport route, and transport environment. Thus far, safety evaluations of radioactive waste transport have mainly targeted operational wastes, that have less radioactivity and a smaller amount per transport than decommissioning wastes. Therefore, in this study, the possible radiation effects during the transport from NPP to disposal facilities were evaluated to reflect the characteristics of the newly developed containers and decommissioning wastes. According to the evaluation results, the exposure dose to transport workers, handling workers, and the public was lower than the domestic regulatory limit. In addition, all exposure dose results were confirmed, through sensitivity analysis, to satisfy the evaluation criteria even under circumstances when radioactive materials were released 100% from the container.

• 한국ITS학회 논문지
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• 제22권5호
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• pp.163-181
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• 2023

자율주행자동차의 센서에 대응하는 시설물의 검지성능을 향상시키는 것은 주행안전성을 향상시키는 데에 도움이 된다. 도로·교통 분야에서는 이를 위하여 도로 인프라 또는 시설물의 개선을 통해 센서에 대한 검지성능을 향상시키기 위한 연구를 수행하고 있다. 본 연구는 이러한 자율주행 지원 인프라 개발 연구의 일환으로 강우 상황에서도 충분히 LiDAR의 검지성능이 확보되어 공사구간에서 시선유도 기능을 유지할 수 있도록 교통콘과 드럼의 형상을 변형하여 이의 개선효과를 실증 실험으로 확인하였다. 개선의 원리는 반사 성능이 증대되며 기존의 시설물과 형상적으로 크게 차이가 나지 않도록 교통콘은 원뿔형 대신 사각뿔형으로, 드럼은 원기둥형 대신 6각기둥형과 8각기둥형으로 각각 제작하였다. 맑은 날과 강우 20 mm/h, 40 mm/h 상황에서 시설물에 대한 LiDAR 검지 데이터를 확인하였으며, 사각뿔형 교통콘과 8각기둥형 드럼은 기존 시설물에 비해 검지성능이 향상되었음을 확인하였다. 다만, 반복 측정에 따른 편차가 발생하였고, 통계적 해석으로는 유의미성을 확인하지 못한 것이 본 연구 결과의 한계이며, 이 결과를 반영하여 향후 연구에서는 측정환경의 다양성에도 균일하게 데이터가 취득될 수 있는 형태로 개선할 필요가 있다.