• Nuclear Engineering and Technology
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• 제39권3호
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• pp.171-186
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• 2007

Critical issues in the development targets for the future fast reactor(FR) cycle system, including sodium-cooled FR were to ensure safety assurance, efficient utilization of resources, reduction of environmental burden, assurance of nuclear non-proliferation, and economic competitiveness. A promising design concept of sodium-cooled fast reactor JSFR is proposed aiming at fully satisfaction of the development targets for the next generation nuclear energy system. A roadmap toward JSFR commercialization is described, to be followed up in a new framework of the Fast reactor Cycle Technology development(FaCT) Project launched in 2006.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1231-1240
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• 2019

Unlike land-based nuclear power plants, a marine or floating reactor is affected by external forces due to ocean conditions. These external forces can cause additional accelerations and affect each system and equipment of the marine reactor. Therefore, in designing a marine reactor and evaluating its performance and stability, a thermal hydraulic safety analysis code is necessary to consider the thermal hydrodynamic effects of ship motion. MARS, which is a reactor system analysis code, includes a dynamic motion model that can simulate the thermal-hydraulic phenomena under three-dimensional motion by calculating the body force term included in the momentum equation. In this study, it was verified that the dynamic motion model can simulate fluid motion with reasonable accuracy using conceptual problems. In addition, two modifications were made to the dynamic motion model; first, a user-supplied table to simulate a realistic ship motion was implemented, and second, the flow regime map determination algorithm was improved by calculating the volume inclination information at every time step if the dynamic motion model was activated. With these modifications, MARS could simulate the thermal-hydraulic phenomena under ocean motion more realistically.

• Journal of Radiation Protection and Research
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• 제30권1호
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• pp.39-44
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• 2005

노심 및 원자로의 구조 및 구성 물질이 확정되어 있지 않은 개발단계의 신형원자로의 압력용기에 대한 $R-{\theta}$좌표에서 차폐해석을 수행하려면, 매번 선원항에 대한 모델작업을 하는데 많은 노력과 시간이 소요된다. 따라서 $R-\theta$좌표에 의한 반경방향의 원자로 압력용기에 대한 차폐해석에 있어서 노심의 기하학적 구조에 영향을 받지 않고 해석할 수 있는 체계를 개발하였다. 개발된 해석체계를 이용하여 육방형 노심배열을 갖는 일체형 원자로의 압력용기에 대한 차폐해석을 수행하여, 그 결과를 MCNP 해석결과와 비교 분석하였다. 분석결과 개발된 해석체계가 좀 더 보수적인 결과를 나타내었으며 이는 차폐해석측면에서 타당하다. 또한 이 해석체계를 개발함으로써 그 동안 수작업으로 작성하였던 노심내부에 대한 모델에 대한 오차를 줄일 수 있으며 이에 소요되는 시간 및 노력을 줄일 수 있을 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제47권5호
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• pp.534-545
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• 2015

In the very high temperature reactor (VHTR), which is a next generation nuclear reactor system, ceramics are used as a fuel coating material and graphite is used as a core structural material. Even if a depressurization accident occurs and the reactor power goes up instantly, the temperature of the core will change only slowly. This is because the thermal capacity of the core is so high. Therefore, the VHTR system can passively remove the decay heat of the core by natural convection and radiation from the surface of the reactor pressure vessel. The objectives of this study are to investigate the heat transfer characteristics of natural convection of a one-side heated vertical channel with inserted porous materials of high porosity and also to develop the passive cooling system for the VHTR. An experiment was carried out using a one-side heated vertical rectangular channel. To obtain the heat transfer and fluid flow characteristics of the vertical channel with inserted porous material, we have also carried out a numerical analysis using a commercial Computational Fluid Dynamics (CFD) code. This paper describes the thermal performances of the one-side heated vertical rectangular channel with an inserted copper wire of high porosity.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.431-431
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• 2012

A compact tokamak reactor concept as a 14 MeV neutron source is desirable from an economic viewpoint for a fusion-driven transmutation reactor. LAR (Low Aspect Ratio) tokamak allows a potential of high "see full txt" operation with high bootstrap current fractions and can be used for a compact fusion neutron source. For the optimal design of a reactor, a radial build of reactor components has to be determined by considering the plasma physics and engineering constraints which inter-relate various reactor components and are constrained to use ITER physics and technology. In a transmutation reactor, the blanket should produce enough tritium for tritium self-sufficiency and the neutron multiplication factor, keff should be less than 0.95 to maintain sub-criticality. The shield should provide sufficient protection for the superconducting toroidal field (TF) coil against radiation damage and heating effects of the fusion neutrons, fission neutrons, and secondary gammas. In this work, characteristics of transmutation reactor based on LAR tokamak is investigated by using the coupled system analysis.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.191-194
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• 2004

A novel type of intelligent microcapsule reactor system was prepared. The reactor can recognize pH change in the medea and control reaction rate by itself. For the reactor system, acrylic acid (AA), N-isopropylacrylamide (NIPAM), and glucose oxidase (GOD) were selected as a pH-responsive device, a gating device according and a reaction device, respectively. Poly(NIPAM-co-AA) (P-NIPAM-co-AA) are known to change its hydrophilicity-hydrophobicity due to pH change. They were integrated in a core-shell microcapsule space. GOD was loaded inside the core space and the pores in the outside shell layer were filled with P-NIPAM-co-AA linear grafted chains as pH-responsive gates by plasma graft filling polymerization method. When P-NIPAM-co-AA gates are hydrophilic at high pH value, this microcapsule permits glucose penetration into the core space and GOD reaction proceeds. However, when P-NIPAM-co-AA gates are hydrophobic at low pH value, this microcapsule forbids glucose penetration and GOD reaction will not occur. The accuracy of this concept was examined.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1442-1450
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• 2017

In liquid metal fast breeder reactors, postulated failures of the plant protection system may lead to serious unprotected accidental consequences. Unprotected transients are generically categorized as transient overpower accidents and transient under cooling accidents. In both cases, core meltdown may occur and this can lead to a molten fuel coolant interaction (MFCI). The understanding of MFCI phenomena is essential for study of debris coolability and characteristics during post-accident heat removal. Sodium is used as coolant in liquid metal fast breeder reactors. Viewing inside sodium at elevated temperature is impossible because of its opaqueness. In the present study, a methodology to depict MFCI phenomena using a flat panel detector based imaging system (i.e., real time radiography) is brought out using a woods metal-water experimental facility which simulates the $UO_2-Na$ interaction. The developed imaging system can capture attributes of the MFCI process like jet breakup length, jet front velocity, fragmented particle size, and a profile of the debris bed using digital image processing methods like image filtering, segmentation, and edge detection. This paper describes the MFCI process and developed imaging methodology to capture MFCI attributes which are directly related to the safe aspects of a sodium fast reactor.

• 환경위생공학
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• 제18권1호
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• pp.15-22
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• 2003

Treatability tests were conducted using EMC process to study the feasibility of applying this process as recycling-water treatment system in high density seawater aquaculture farm. To study the effect of organic and ammonia nitrogen loading on system performance, hydraulic retention time of reactor was reduced gradually from 12hr to 10min. The conclusions are can be summarized as follows. When the system HRT was reduced from 12hr to 10 min gradually, there was little noticeable change(reduction) in ammonia nitrogen removal efficiencies until 2hr of HRT, however, removal efficiencies were decreased dramatically when the system was operated under the HRT of less than 2hr. In case of organics(COD), there was no dramatic deterioration in removal efficiencies depending on HRT reduction. More than 90% of removal efficiencies were maintained successfully when the system was operated at the HRT of 10 min. In case of system performance depending on media packing ratio in reactor, there was little difference in each reactor performance depending on media packing ratio in reactor when the reactors were operated under the HRT of longer than 1hr, however, differences in reactor performances were considerably evident when the reactors were operated under the HRT of shorter than 1hr. That is, the more reactor was packed, the better reactor performed. When comparing reactor performance among 25%, 50%, 75% packed reactor, it can be judged that media packing ratio more than 50% plays no significant role in increasing reactor performance. For this reason, packing the media less than 50% is more reasonable way in view of economic. Such a tendency well agreed with the variation of ammonia-nitrogen removal efficiencies according to the media packing ratio in reactors at each HRT. Difference in effluent ammonia-nitrogen concentration between 50% media packing reactor and 75% media packing reactor was negligible. When comparing with the results of 25% packing reactor, difference was not so great.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2063-2065
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• 2003

The control rod drive mechanisms in a reactor head are arranged too narrow for a human worker to approach. Moreover, the working environment is in high radiation area. In order to inspect defections in the surfaces of the reactor head and welding parts, a visual inspection device that can approach such a narrow and high radiation area is required. This paper introduces a tele-operated mobile robot for visual inspection of a reactor head, which has pan/tilt camera, fixed rear camera, ultrasonic collision detection system, and so on. Moreover, the host controller and digital video logging system are developed and integrated control software is also developed. The robot is operated by a wireless control, which gives flexibility for the inspection.

• 상하수도학회지
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• 제32권1호
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• pp.11-18
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• 2018

As the sequencing batch reactor process is a time-oriented system, it has advantages of the flexibility in operation for the biological nutrient removal. Because the sequencing batch reactor is operated in a batch system, respiration rate is more sensitive and obvious than in a continuous system. The variation of respiration rate in the process well represented the characteristics of biological reactions, especially nitrification. The respiration rate dropped rapidly and greatly with the completion of nitrification, and the maximum respiration rate of nitrification showed the activity of nitrifiers. This study suggested a strategy to control the aeration of the sequencing batch reactor based on respirometry. Aeration time of the optimal aerobic period required for nitrification was daily adjusted according to the dynamics of respiration rate. The aeration time was mainly correlated with influent nitrogen loadings. The anoxic period was extended through aeration control facilitating a longer endogenous denitrification reaction time. By respirometric aeration control in the sequencing batch reactor, energy saving and process performance improvement could be achieved.