• Title/Summary/Keyword: Reference fuel

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An approach to minimize reactivity penalty of Gd2O3 burnable absorber at the early stage of fuel burnup in Pressurized Water Reactor

  • Nabila, Umme Mahbuba;Sahadath, Md. Hossain;Hossain, Md. Towhid;Reza, Farshid
    • Nuclear Engineering and Technology
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    • v.54 no.9
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    • pp.3516-3525
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    • 2022
  • The high capture cross-section (𝜎c) of Gadolinium (Gd-155 and Gd-157) causes reactivity penalty and swing at the initial stage of fuel burnup in Pressurized Water Reactor (PWR). The present study is concerned with the feasibility of the combination of mixed burnable poison with both low and high 𝜎c as an approach to minimize these effects. Two considered reference designs are fuel assemblies with 24 IBA rods of Gd2O3 and Er2O3 respectively. Models comprise nuclear fuel with a homogeneous mixture of Er2O3, AmO2, SmO2, and HfO2 with Gd2O3 as well as the coating of PaO2 and ZrB2 on the Gd2O3 pellet's outer surface. The infinite multiplication factor was determined and reactivity was calculated considering 3% neutron leakage rate. All models except Er2O3 and SmO2 showed expected results namely higher values of these parameters than the reference design of Gd2O3 at the early burnup period. The highest value was found for the model of PaO2 and Gd2O3 followed by ZrB2 and HfO2. The cycle burnup, discharge burnup, and cycle length for three batch refueling were calculated using Linear Reactivity Model (LRM). The pin power distribution, energy-dependent neutron flux and Fuel Temperature Coefficient (FTC) were also studied. An optimization of model 1 was carried out to investigate effects of different isotopic compositions of Gd2O3 and absorber coating thickness.

Analysis of Electrode Polarization in MCFC by a Reference Electrode (기준 전극을 이용한 용융탄산염 연료전지의 분극 특성 해석)

  • Han Jonghee;Lee Kab Soo;Chung Chang-Yeol;Yoon Sung-Pil;Nam Suk-Woo;Lim Tae-Hoon;Hong Seong-Ahn
    • Journal of the Korean Electrochemical Society
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    • v.4 no.3
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    • pp.125-131
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    • 2001
  • A long-term variation of electrode polarization in the MCFC has been analyzed successfully using a single cell with a Au, $CO_2/O_2$ reference electrode Four different cells with different components were operated and their electrode polarizations were analyzed. As published in the literatures, the cathode polarization was larger than that of the anode. The more stable operation of a single cell with the Al-coated cell frame up to 6,000hrs indicates that the corrosion at the cell frame, particularly wet seal area, plays an important role to determine the lifetime of a MCFC. At the initial stage of the cell operation, the voltage of the cell using a cathode stabilized by the $LiCoO_2$ coating was relatively low due to the high cathode polarization. As the cell was operated and the stabilized cathode was lithiated sufficiently, the cathode polarization decreased and the cell voltage was recovered. It was observed that the voltage of the cell using the $Li_2CO_3/Na_2CO_3$ electrolyte fluctuated with operation time and the cathode polarization fluctuated along with the cell voltage quite similarly. Although the mechanisms of the voltage fluctuation were not clear yet, the results imply that the voltage fluctuation was related with a reaction in the cathode side. After testing every single cell, the cathode polarization increased with the steep decrease in the cell voltage. Thus, the cathode should be improved in order to develop more durable MCFC.

CORE DESIGN FOR HETEROGENEOUS THORIUM FUEL ASSEMBLIES FOR PWR(1)-NUCLEAR DESIGN AND FUEL CYCLE ECONOMY

  • BAE KANG-MOK;KIM MYUNG-HYUN
    • Nuclear Engineering and Technology
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    • v.37 no.1
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    • pp.91-100
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    • 2005
  • Kyung-hee Thorium Fuel (KTF), a heterogeneous thorium-based seed and blanket design concept for pressurized light water reactors, is being studied as an alternative to enhance proliferation resistance and fuel cycle economics of PWRs. The proliferation resistance characteristics of the KTF assembly design were evaluated through parametric studies using neutronic performance indices such as Bare Critical Mass (BCM), Spontaneous Neutron Source rate (SNS), Thermal Generation rate (TG), and Radio-Toxicity. Also, Fissile Economic Index (FEI), a new index for gauging fuel cycle economy, was suggested and applied to optimize the KTF design. A core loaded with optimized KTF assemblies with a seed-to-blanket ratio of 1: 1 was tested at the Korea Next Generation Reactor (KNGR), ARP-1400. Core design characteristics for cycle length, power distribution, and power peaking were evaluated by HELIOS and MASTER code systems for nine reload cycles. The core calculation results show that the KTF assembly design has nearly the same neutronic performance as those of a conventional $UO_2$ fuel assembly. However, the power peaking factor is relatively higher than that of conventional PWRs as the maximum Fq is 2.69 at the M$9^{th}$ equilibrium cycle while the design limit is 2.58. In order to assess the economic potential of a heterogeneous thorium fuel core, the front-end fuel cycle costs as well as the spent fuel disposal costs were compared with those of a reference PWR fueled with $UO_2$. In the case of comprising back-end fuel cycle cost, the fuel cycle cost of APR-1400 with a KTF assembly is 4.99 mills/KWe-yr, which is lower than that (5.23 mills/KWe-yr) of a conventional PWR. Proliferation resistance potential, BCM, SNS, and TG of a heterogeneous thorium-fueled core are much higher than those of the $UO_2$ core. The once-through fuel cycle application of heterogeneous thorium fuel assemblies demonstrated good competitiveness relative to $UO_2$ in terms of economics.

Thermal, Hydraulic and Mechanical Analysis for Disposal of Spent Nuclear Fuel in Saturated Rock Mass in the KBS-3 Concept. (KBS-3 개념에 따른 포화된 암반내 사용후핵연료 처분을 위한 열, 수리, 역학적 특성 해석)

  • 장근무;황용수;김선훈
    • Tunnel and Underground Space
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    • v.7 no.1
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    • pp.39-50
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    • 1997
  • Reference concepts for the disposal of spent nuclear fuel and the current status of underground rock laboratory were studied. An analysis to simulate the deep disposal of spent nuclear fuel in saturated rock mass was conducted. Main input parameters for numerical study were determined based on the KBS-3 concept. A series of results showed that the temperature distribution around a cavern reached the maximum value at about 10 years after the emplacement of spent fuel. The maximum temperature at the surface of canister was more than about 12$0^{\circ}C$ at about 4 years. This temperature was not much higher than the temperature criteria to meet the performance criteria of an artificial barrier in the KBS-3 concept. The maximum upward displacement due to the heat generation of spent fuel was about 0.9cm at about 10 years after the emplacement of spent fuel. It turned out that the vertical displacement became smaller with the decrease in heat generation of a canister. The quantity of groundwater inflow into a disposal tunnel increased by about 1.6 times at 20 years after the emplacement of spent fuel with the increase of pore pressure around a cavern.

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Analysis on the heat-resisting method of the electrolytic metal reduction reactor in the test facility for the spent fuel waste (사용후핵연료 시험시설에서 전기 금속 전환반응기의 내열 방안 분석)

  • 김영환;윤지섭;정재후;홍동희;박기용;진재현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.776-779
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    • 2003
  • To reduce the storage space of spent fuel used at the atomic power plants in the over the world, the uranium elements contained in the spent fuel is being extracted and effectively stored. For this, the spent fuel are oxidized and deoxidized. In this study, it is produced the heat-resisting methods about the spent fuel management technology research and test facility for the spent fuel waste for spent fuel minimized. The first considered processes in the facility are the electrolytic metal reduction reactor process. Since the electrolytic metal reduction reactor is operated at the high temperature range, we have to consider the heat-resisting methods for the devices. For the heat-resisting methods, we have searched and analyzed technical reference for the heat-resisting methods. We have calculated thermal stress and strain of each devices by the commercial analysis software, ANSYS. D.S. It is experimented for inspecting confidence rate of analysis results. By using the results, we have analyzed the problems of parts and determined the heat-resisting material, commercial parts, and the size of parts and O-ring. Based on these results, it is produced the heat-resisting methods of magnesia filter, cathode, and reactor for the electrolytic metal reduction reactor.

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A study on DCGL determination and the classification of contaminated areas for preliminary decommission planning of KEPCO-NF nuclear fuel fabrication facility

  • Cho, Seo-Yeon;Kim, Yong-Soo;Park, Da-Won;Park, Chan-Jun
    • Nuclear Engineering and Technology
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    • v.51 no.8
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    • pp.1951-1956
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    • 2019
  • As a part of the preliminary decommissioning plan of KEPCO-NF fuel fabrication facility, DCGLs of three target radionuclides, 234U, 235U, and 238U, were derived using RESRAD-BUILD code and contaminated areas of the facility were classified based on contamination levels from the derived DCGLs. From code simulations, one-room modeling results showed that the grinding room in building #2 was the most restrictive (DCGLgross = 10493.01 Bq/㎡). The DCGLgross results in contaminated areas from one-room modeling were slightly more conservative than three-room modeling. Prior to the code simulation, field survey and measurements conducted by each survey unit. For a conservative approach, the most restrictive DCGLgross in each survey unit was taken as a reference to classify the contaminated areas of the facility. Accordingly, seven rooms and 37 rooms in the nuclear-fuel buildings were classified as Class 1 and Class 2, respectively. As expected, fuel material handling and processing rooms such as the grinding room, sintering room, compressing room, and powder collecting room were included in the Class 1 area.

PEMFC Based Cogeneration System Using Heat Pump (히트펌프를 이용한 PEMFC 기반 열병합 발전 시스템)

  • BUI, TUANANH;KIM, YOUNG SANG;LEE, DONG KEUN;AHN, KOOK YOUNG
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.5
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    • pp.324-330
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    • 2021
  • In recent years, polymer electrolyte membrane fuel cell (PEMFC) based cogeneration system has received more and more attention from energy researchers because beside electricity, the system also meets the residential thermal demand. However, the low-quality heat exited from PEMFC should be increased temperature before direct use or storage. This study proposes a method to utilize the heat exhausted from a 10 kW PEMFC by coupling a heat pump. Two different configuration using heat pump and a reference layout with heater are analyzed in term of thermal and total efficiency. The system coefficient of performance (COP) increases from 0.87 in layout with heaters to 1.26 and 1.29 in configuration with heat pump and cascade heat pump, respectively. Lastly, based on system performance result, another study in economics point of view is proposed.

Force Control of the NFBC Compactor Using Fuzzy Algorithm

  • Yoon, Ji-Sup;Kim, Young-Hwan;Song, Sang-Ho;Kang, E-Sok
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.123.3-123
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    • 2001
  • To recycle the uranium resources in the spent nuclear fuels, all the fuel rods are extracted from the spent fuel assemblies. The remaining components of the spent fuel assembly after extracting all the rods, so called a NFBC(Non-Fuel Bearing Components), should be compacted to minimize the waste volume. To this present, KAERI (Korea Atomic Research Institute) has developed he NFBC compactor by introducing a new concept of cutting and compaction, In this paper, to achieve he maximum compaction ration of the NFBC volume while reducing compactor size, an fuzzy controller, which determines the reference force of the compactor, is proposed with using he fuzzy-inference.

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An Experimental Investigation of Air Fuel Ratio Measurement using Laser Induced Acetone Fluorescence (아세톤 형광을 이용한 공연비 측정 기법 연구)

  • Park Seungjae;Huh Hwanil;Oh Seungmook
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.353-356
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    • 2002
  • Planar laser induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Preliminary investigation was performed to measure quantitative air excess ratio distribution in an engine fueled with LPG. It is known that fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone was excited by KrF excimer laser (248nm) and its fluorescence image was acquired by ICCD camera with a cut-of filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile was suggested. Raw images were divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which was taken by a calibration process, were converted to air excess ratio distribution. This investigation showed instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

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A Study on the Improvement of Air-Fuel Ratio Control Performance in Sl Engine Using STR (STR을 이용한 가솔린 엔진의 공연비 제어 성능 향상에 관한 연구)

  • 신규철;박승범;윤팔주;정남훈;선우명호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.6
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    • pp.57-64
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    • 2001
  • This study presents an self tuning regulator(STR) to improve the air-fuel ratio control of performance of gasoline engine. The STR is designed based on the nonlinear dynamic engine model, and the performance of the STR is evaluated through the simulation and experiments. The STR shows better performance than a conventional PI controller in terms of the response time and disturbance rejection. Since the STR has less calculation load than the complex nonlinear controller, this algorithm can be easily applied to on-board engine controller.

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