• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 제10회 단조 심포지엄
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• pp.131-139
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• 2005

Reactor Vessel is one of the most important structural part of nuclear power plant. It is manufactured by various steel forgings such as shell, head and transition ring. Head forgings has been made by open die forging process. After steel melting and ingot making, open die forging has been carried out to get a good quality which means high soundness and homogeniety of the steel forgings by using high capacity hydraulic press. This paper introduced the development trend of the open die forging process and manufacturing experience of large head forgings which canl be used for the reactor vessel of nuclear power plant.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.397-400
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• 2005

Reactor Vessel is one of the most important structural part of nuclear power plant. It is manufactured by various steel forgings such as shell, head and transition ring. Head forgings has been made by open die forging process. After steel melting and ingot making, open die forging has been carried out to get a good quality which means high soundness and homogeniety of the steel forgings by using high capacity hydraulic press. This paper introduced the open die forging process and manufacturing experience of large head forgings which cant be used for the reactor vessel of 1,000MW nuclear power plant.

• 한국환경과학회지
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• 제9권4호
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• pp.351-367
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• 2000

Air-lift biofilm reactor should be an admirable process substituting conventional activated sludge process, because of its small area requirement as well as high volumetric loading capacity and stability against loading and chemical shocks. However most of the past research on the performance of ABR was focused on the sewage treatment. This research studied the applicability of ABR to treat high strength wastewater. A bench-scale ABR was operated to treat high strength synthetic wastewater, tannery wastewater and petrochemical wastewater, and its applicability was conclusive In case of synthetic wastewater, ABR showed good performance in which the substarate removal efficiency was higher that 80% even under short HRT(1.4 hr) and high volumetric loading rate(9.3 kgCODcr/$m^3$.day). When ABR was applied to treat tannery wastewater, it was suggested that the maximum volumetric loading rate and F/M ratio should be 7.7kgCODcr/$m^3$.day, 0.76 $day^{-1}$, respectively. And high substrate removal efficiency over than 90 % was observed with 4,000 mgCODcr/L of petrochemical wastewater. Even though effluent concentration was quite high, ABR should be applicable to treat the high strength wastewater, because of its high loading capacity.

• 한국안전학회지
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• 제32권2호
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• pp.1-6
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• 2017

Modern society has been experiencing by population growth and urbanization that bring, a change of eating habits which has occurred a various types of waste in a large amount. Even though these wastes are required an immediate treatment with difficulties unsanitary handling and existing waste treatment method are by incineration, fermentation, drying and etc. however a bad smell occurs after the treatment that need's a lot of energy in processing organic wastes with high moisture contents and wasteful and inefficient problem. The strength assessment of the organic waste agitating vessel is required in terms of safety due to the differences of loading on the shaft that was treated by agitating the mixture of food waste. The damage of agitating axis is depended on steam pressure, temperature condition and the force moment that exerted by the food waste. Thus the strength assessment and stability evaluation are very important, especially to handle a hard waste. In this study the rotation capacity of agitation is about 5 tons considering general structural rolled steel pressure vessel strength and steam pressure. The purpose is to estimate the safety and strength evaluation for a agitator axis and impellers according to the rotating angle of the axis under the condition of the 3.2 ton capacity reactor.

• 한국환경과학회지
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• 제11권3호
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• pp.263-269
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• 2002

This study was conducted to know the removal characteristics of ammonia nitrogen by commercially available cation exchange resins. Eight acidic cation exchange resins were investigated in batch reactors. Among them, the most effective resin for ammonia removal in solution was PK228, which was a strong acidic resin of $Na^{+}$ type. PK228 was compared with activated carbon and natural zeolite. The effects of cation exchange capacity, ammonia concentration, resin amount, temperature and pH on ammonia removal by PK228 were investigated in batch reactor, and the effect of effluent velocity in continuous column reactor. Strong acidic resins of porous type were more effective than week acidic resins or gel type resins for ammonia removal in solution. PK228 was more effective than activated carbon and natural zeolite for ammonia removal in batch reactor. With increasing initial ammonia concentration, the amount of ammonia removed by PK228 increased, but the proportion of removed ammonia to initial ammonia concentration decreased. The effect or temperature on ammonia removal by PK228 was very slight. The ammonia removal to acidic solution was more effective than that at basic solution. With decreasing effluent velocity of solution through column, breakthrough point extended, and ammonia removal capacity increased.d.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.367-376
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• 2013

This study investigated mixing scenarios of the low and high conversion ratios (CRs) of fast reactors (FRs). The fuel cycle was modeled so as to minimize the spent fuel (SF) or transuranics (TRU) inventories. The scenarios were modeled for a single low CR of 0.61 and a high CR of 1.0. The study also investigated the mixing scenario of low-high CR and/or high-low CR. The SF and TRU inventories, associated with different scenarios, were compared to those of the light water reactor (LWR) once-through (OT) case. Also, the important isotope concentration and long-term heat (LTH) load were calculated and compared to those of the OT cycle. As a result, it is known that the deployment of FRs of low CR burns more TRU and results in a reduction of the out-of-pile TRU inventory and LTH with low deployment capacity. This study shows that the mixing strategy of FRs of low and high CR can reduce the SF and TRU inventories with lower deployment capacity as compared with a single deployment of FRs of high CR.

• 한국초전도ㆍ저온공학회논문지
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• 제17권1호
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• pp.32-35
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• 2015

Many kinds of high temperature superconducting (HTS) devices are being developed due to its several advantages. In particular, the advantages of HTS devices are maximized under the DC condition. A line commutated converter (LCC) type high voltage direct current (HVDC) transmission system requires large capacity of DC reactors to protect the converters from faults. However, conventional DC reactor made of copper causes a lot of electrical losses. Thus, it is being attempted to apply the HTS DC reactor to an HVDC transmission system. The authors have developed a 8 mH class HTS DC reactor and a model-sized LCC type HVDC system. The HTS DC reactor was operated to analyze its operational characteristics in connection with the HVDC system. The voltage at both ends of the HTS DC reactor was measured to investigate the stability of the reactor. The voltages and currents at the AC and DC side of the system were measured to confirm the influence of the HTS DC reactor on the system. Two 5 mH copper DC reactors were connected to the HVDC system and investigated to compare the operational characteristics. In this paper, the operational characteristics of the HVDC system with the HTS DC reactor according to firing angle are described. The voltage and current characteristics of the system according to the types of DC reactors and harmonic characteristics are analyzed. Through the results, the applicability of an HTS DC reactor in an HVDC system is confirmed.

• 한국미생물·생명공학회지
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• 제18권5호
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• pp.525-529
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• 1990

식물세포인 Lithospermum erythrorhizon을 교반 반응기와 calcium alghinate에 고정화된 상태로 충전층 반응기에서 n-hexadecane으로 동시 추출하면서 shikonin을 생산하여 각각의 생산성을 비교하였다. 교반 반응기에서 shikonin의 비생산과 부피생산성은 각각 1.5mg shikonin/g cell과 400$\mu g$ shikonin/(L.day)였고 충전층 반응기에서는 가각 2.0mg shikonin/g cell과 2857 $\mu g$ shikonin/(L.day)였으며 이는 각각 교반 반응기에 비하여 1.3, 7.1배 높은 것이다. 충전층 반응기에서 shikonin의 생산성이 높은 것은 calcium alginate 입자에 세포가 고농도고 축적되어 단위 반응기 부피당 세로의 부하 능력이 높고 또한 세포가 서로 접촉하기가 쉽고 고정화 입자내의 환경이 세포가 분화하기에 좋은 조건을 형성하기 때문인 것으로 사료된다.

• 한국안전학회지
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• 제32권2호
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• pp.147-152
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• 2017

The external reactor vessel cooling (ERVC) is well known strategy to mitigate a severe accident at which nuclear fuel inside the reactor vessel is molten. In order to compare the heat removal capacity of ERVC between the nuclear reactor designs quantitatively, numerical method is often used. However, the study for ERVC using computational fluid dynamics (CFD) is still quite scarce. As a validation study on the numerical prediction for ERVC using CFD, the subcooled boiling flow and natural circulation of coolant at the ULPU-V experiment was simulated. The commercially available CFD software ANSYS-CFX was used. Shear stress transport (SST) model and RPI model were used for turbulence closure and wall-boiling, respectively. The averaged flow velocities in the downcomer and the baffle entry under the reactor vessel lower plenum are in good agreement with the available experimental data and recent computational results. Steam generated from the heated wall condenses rapidly and coolant flows maintains single-phase flow until coolant boils again by flashing process due to the decrease of saturation temperature induced by higher elevation. Hence, the flow rate of coolant natural circulation does not vary significantly with the change of heat flux applied at the reactor vessel, which is also consistent with the previous literatures.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.248.1-248
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• 1999

Preliminary analysis of in-reactor thermal performance of three MOX fuel rods, which are going to be irradiated in the Halden reactor beginning in the first Quarter of the year 2000 under the framework of the OECD Halden Reactor Programme, have been conducted by using the computer code COSMOS to ensure their safe operation. Parametric studies have been carried out to investigate the effect of uncertainties on in-reactor behavior by considering the four kinds of uncertainties; thermal conductivity, linear power, manufacturing parameters, and model constants. The analysis shows that, in the case of annular MOX -1 fuel, calculation results for thermal performance vary widely depending on the selection of model constants for fission gas release (FGR). On the contrary, the thermal performance of solid MOX - 3 fuel does not depend on the choice of FGR constants to a large extent as MOX-I, because the fuel temperature is very high in the MOX-3 irrespective of the choice of FGR constants and hence the capacity of grain boundaries to retain gas atoms is not large enough to accommodate the number of gas atoms reaching the grain boundaries. It is planned that when the data on microstructure and thermal conductivity for each type of MOX fuel are available, new analysis will be made using these information. In addition, FGR model constants will be derived from the measured fuel centerline temperature, rod internal pressure and other related data.