FUEL PERFORMANCE CODE COSMOS FOR ANALYSIS OF LWR UO2 AND MOX FUEL

BYUNG-HO LEE,구양현,JAE-YONG OH,Jin-SikCheon,YOUNG-WOOK TAHK,손동성 한국원자력학회 2011 Nuclear Engineering and Technology Vol.43 No.6

The paper briefs a fuel performance code, COSMOS, which can be utilized for an analysis of the thermal behavior and fission gas release of fuel, up to a high burnup. Of particular concern are the models for the fuel thermal conductivity, the fission gas release, and the cladding corrosion and creep in UO2 fuel. In addition, the code was developed so as to consider the inhomogeneity of MOX fuel, which requires restructuring the thermal conductivity and fission gas release models. These improvements enhanced COSMOS’s precision for predicting the in-pile behavior of MOX fuel. The COSMOS code also extends its applicability to the instrumented fuel test in a research reactor. The various in-pile test results were analyzed and compared with the code’s prediction. The database consists of the UO2 irradiation test up to an ultra-high burnup, power ramp test of MOX fuel, and instrumented MOX fuel test in a research reactor after base irradiation in a commercial reactor. The comparisons demonstrated that the COSMOS code predicted the in-pile behaviors well, such as the fuel temperature, rod internal pressure, fission gas release, and cladding properties of MOX and UO2 fuel. This sufficient accuracy reveals that the COSMOS can be utilized by both fuel vendors for fuel design, and license organizations for an understanding of fuel in-pile behaviors.

Analyses and improvement of fuel temperature coefficient of rock-like oxide fuel in LWRs from neutronic aspect

Shelley, Afroza Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6

Fuel temperature coefficient (FTC) of PuO₂+ZrO₂ (ROX) fueled LWR cell is analyzed neutronically with reactor- and weapons-grade plutonium fuels in comparison with a U-free PuO₂+ThO₂ (TOX), and a conventional MOX fuel cells. The FTC value of a ROX fueled LWR is smaller compared to a TOX or a MOX fueled LWRs and becomes extremely positive especially, at EOL. This is because when fuel temperature is increased, thermal neutron spectrum is shifted to harder, which is extreme at EOL in ROX fuel than that in TOX and MOX fuels. Consequently at EOL, ²³⁹Pu and ²⁴¹Pu contributes to positive fuel temperature reactivity (FTR) in ROX fuel, while they have negative contribution in TOX and MOX fuels. The FTC problem of ROX fuel is mitigated by additive ThO₂, UO₂ or Er₂O₃. In ROX-additive fuel, the atomic density of fissile Pu becomes more than additive free ROX fuel especially at EOL, which is the main cause to improve the FTC problem. The density of fissile Pu is more effective to decrease the thermal spectrum shifts with increase the fuel temperature than additive ThO₂, UO₂ or Er₂O₃ in ROX fuel.

Ignition delay time and sooting propensity of a kerosene aviation jet fuel and its derivative blended with a bio-jet fuel

Han, Hee Sun,Kim, Chul Jin,Cho, Cheon Hyeon,Sohn, Chae Hoon,Han, Jeongsik Elsevier 2018 Fuel Vol.232 No.-

<P><B>Abstract</B></P> <P>Ignition delay time and sooting index of kerosene blended with a bio-jet fuel is measured for a comparative study with general aviation fuels. The new blended fuel is similar to a kerosene jet fuel (Jet A-1 or Korean domestic jet fuel) in terms of properties, H/C ratio, density, and heat of combustion. But, its ignition characteristics and sooting propensity are different from those of Jet A-1. Ignition delay time is measured by a shock tube and it is found that the blended fuel of kerosene and a bio-jet fuel has NTC (negative temperature coefficient) behavior. Ignition delay times of the blended fuel are compared with those of jet fuels (Jet A-1 and Jet A) over a wide range of temperature from 700 K to 1200 K at 20 atm. The blended fuel has shorter ignition delay time at low temperature below 900 K. It can be explained by short ignition delay of components in a bio-jet fuel at low temperature. In terms of sooting propensity, blending with a bio-jet fuel reduces the propensity remarkably to a half.</P>

GPS 데이터를 이용한 차량의 연료소모량 연산법 연구

고광호,Ko, Kwang-Ho 한국산업융합학회 2020 한국산업융합학회 논문집 Vol.23 No.6

It's important to measure fuel consumption of vehicles. It's possible to monitor green house gas from vehicles for various traffic conditions with the measured data. It's effective to eco-drive for drivers with fuel consumption data also. There's a display of fuel consumption in the modern vehicles, but it's not useful to get the data from the display. An estimating method for fuel consumption of a vehicle is suggested in the study. It's a simple but an effective method using GPS data. The GPS data(speed, acceleration, road slope) and vehicle data(weight, frontal area, model year, certified fuel economy) is necessary to estimate the fuel consumption for the method. It calculates driving resistance force to estimate engine power. Then it estimates the necessary fuel consumption to maintain the engine power with fuel-power conversion factor. The conversion factor is corrected with certified fuel economy, model year and rated power. The precision of the methods is checked with road test data. The test driving data was measured with GPS and OBD. The error of the estimated fuel consumption for the measured one is about 1.8%. But the error is large for the 1000 and 100 data number from the total data number of about 10,000. The error is from the larger change range of the GPS data than the one of the measured fuel consumption data. But the proposed estimating method is useful to percept the fuel consumption change for better fuel economy with simple gadget like smart phone or other GPS instruments.

FUEL PERFORMANCE CODE COSMOS FOR ANALYSIS OF LWR UO₂ AND MOX FUEL

Lee, Byung-Ho,Koo, Yang-Hyun,Oh, Jae-Yong,Cheon, Jin-Sik,Tahk, Young-Wook,Sohn, Dong-Seong Korean Nuclear Society 2011 Nuclear Engineering and Technology Vol.43 No.6

The paper briefs a fuel performance code, COSMOS, which can be utilized for an analysis of the thermal behavior and fission gas release of fuel, up to a high burnup. Of particular concern are the models for the fuel thermal conductivity, the fission gas release, and the cladding corrosion and creep in $UO_2$ fuel. In addition, the code was developed so as to consider the inhomogeneity of MOX fuel, which requires restructuring the thermal conductivity and fission gas release models. These improvements enhanced COSMOS's precision for predicting the in-pile behavior of MOX fuel. The COSMOS code also extends its applicability to the instrumented fuel test in a research reactor. The various in-pile test results were analyzed and compared with the code's prediction. The database consists of the $UO_2$ irradiation test up to an ultra-high burnup, power ramp test of MOX fuel, and instrumented MOX fuel test in a research reactor after base irradiation in a commercial reactor. The comparisons demonstrated that the COSMOS code predicted the in-pile behaviors well, such as the fuel temperature, rod internal pressure, fission gas release, and cladding properties of MOX and $UO_2$ fuel. This sufficient accuracy reveals that the COSMOS can be utilized by both fuel vendors for fuel design, and license organizations for an understanding of fuel in-pile behaviors.

상용 수소전기차 도입을 위한 연료비용 경쟁력 분석

백현조,박지영,김자인 한국교통연구원 2021 交通硏究 Vol.28 No.1

Fuel Cell Electric Vehicles(FCEVs) are emerging as carbon-neutral solution for long haul and heavy-duty commercial vehicle such as bus, taxi and truck. Especially, fuel cost competitiveness is a crucial factor considering the long life cycle of commercial vehicles. Therefore, this study analyzed the changes in fuel costs in the conversion of representative models of commercial FCEV. The types of commercial FCEV are buses which is running on the actual route and taxis and trucks that are in the pilot stage, but are highly likely to be commercialized, comparing the representative models currently used with FCEV. The fuel unit price and fuel economy of the FCEV model currently used were selected as factors affecting the fuel costs. The change in fuel costs and the appropriate hydrogen fuel unit price were analyzed according to the variation of the two factors. As a result, The higher the unit price of existing fuel or the higher the fuel economy of hydrogen fuel, the more cost-competitive the hydrogen fuel is. In addition, it was analyzed that the market competitiveness of FCEV will increase if fuel subsidies currently supported for commercial vehicles are finished and converted to a low-carbon fuel-centered support system. Assuming that the changes of current fuel price and fuel economy of FCEVs, the hydrogen fuel price, which becomes the same as the fuel cost of FCEVs, has been calculated. The results showed that fuel cell electric taxis can have price competitiveness in the range of 5,306 to 9,131 won/kg, 3,203 to 5,512 won/kg for fuel cell electric buses, and 2,013 to 3,464 won/kg for fuel cell electric trucks. 친환경 미래모빌리티로서 수소전기차가 등장하고 버스, 택시, 트럭 등 상용차까지 도입 차종이 확대되고 있다. 상용차 차종선택에 있어서 경제성은 중요한 선택요인이다. 특히 차종 특성상 총 소유비용에서 연료비용이 차지하는 비율은 차량가격보다 높다. 따라서 차종 전환에 있어서 연료비용 경쟁력은 매우 중요하다. 본 연구는 수소전기차 도입 차종 중 상용차를 대상으로 연료비용 가격경쟁력을 분석하고 가격경쟁력에 영향을 미치는 요인별로 민감도 분석을 실시하였다. 대상 차종은 이미 국내에도 출시된 수소버스와 출시 계획중인 수소택시와 수소트럭의 총 3종을 선택했고 기존 차종과 연료비용을 비교했다. 각 차종별 내구연한 동안 연료비용을 비교한 결과 수소택시는 795만원, 수소버스는 1억 9천만원, 수소트럭은 2억 5천만원의 추가 비용이 발생하는 것으로 나타났다. 장래 기존 연료가격 변동과 수소전기차 연비 향상을 가정하고 민감도 분석을 실시했다. 그 결과 수소택시는 수소 연료단가 약 5,306원~9,131원/kg, 수소버스는 3,203원~5,512원/kg, 수소트럭은 2,013원~3,464원/kg 가격 범위에서 연료비용 경쟁력을 갖는 것으로 나타났다.

Code Requirements for Fuel Handling Equipment at Nuclear Power Plant

장상균,강태교,김종민,정종필 한국방사성폐기물학회 2022 방사성폐기물학회지 Vol.20 No.1

This study provides technical information about the nuclear fuel handling process, which consists of various subprocesses starting from new fuel receipt to spent fuel shipment at a nuclear power plant and the design requirements of fuel handling equipment. The fuel handling system is an integrated system of equipment, tools, and procedures that allow refueling, handling and storage of fuel assemblies, which comprise the fuel handling process. The understanding and reaffirming of detailed code requirements are requested for application to the design of the fuel handling and storage facility. We reviewed the design requirements of the fuel handling equipment for its adequate cooling, prevention of criticality, its operability and maintainability, and for the prevention of fuel damage and radiological release. Furthermore, we discussed additional technical issues related to upgrading the current code requirements based on the modification of the fuel handling equipment. The suggested information provided in this paper would be beneficial to enhance the safety and the reliability of the fuel handling equipment during the handling of new and spent fuel.

COMBUSTION DEVELOPMENT OF A BI-FUEL ENGINE

O. S. ABIANEH,M. MIRSALIM2,F. OMMI 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.1

Environmental improvement and energy issues are increasingly becoming more important as worldwide concerns. Natural gas is a good alternative fuel that can help to improve these issues because of its large quantity and clean burning characteristics. This paper provides the experimental performance results of a Bi-Fuel engine that uses Compressed Natural Gas as its Primary fuel and gasoline as its secondary fuel. This engine is a modification of the basic 1.4-liter gasoline engine. Generally, on the unmodified base engine, torque and power for CNG fuel are considerably lower than gasoline fuel. In this paper, the influence of fuels on wall temperature, performance and emissions are investigated. Environmental improvement and energy issues are increasingly becoming more important as worldwide concerns. Natural gas is a good alternative fuel that can help to improve these issues because of its large quantity and clean burning characteristics. This paper provides the experimental performance results of a Bi-Fuel engine that uses Compressed Natural Gas as its Primary fuel and gasoline as its secondary fuel. This engine is a modification of the basic 1.4-liter gasoline engine. Generally, on the unmodified base engine, torque and power for CNG fuel are considerably lower than gasoline fuel. In this paper, the influence of fuels on wall temperature, performance and emissions are investigated.

Assessment of Potential Degradation Mechanisms to Resolve Integrity Issues of CANDU Spent Fuel

Kang Moon Lee,Nam Ho Lee,Seong Ki Lee,Jong Sung Yoo 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Maintaining fuel sheath integrity during dry storage is important. Intact sheath acts as the primary containment barrier for both fuel pellets and fission products over the dry storage periods and during subsequent fuel handling operations. In KNF, in-house fuel performance code was developed to predict the overall behavior of a fuel rod under normal operating conditions. It includes the analysis modules to predict temperature, pellet cracking and deformation, sheath stress and strain at the mid-plane of the pellet and pellet-pellet interfaces, fission gas release and internal gas pressure. The main focus of the code is to provide information on initial conditions prior to dry storage, such as fission gas inventory and its distribution within the fuel pellet, initial volumes of storage spaces and their locations, radial profile of heat generation within the pellet, etc. To upgrade the developed code that address all the damage mechanisms, the first step was a review of the available technical information on phenomena relevant to fuel integrity. Potential degradation mechanisms that may affect sheath integrity of CANDU spent fuel during dry storage are: creep rupture under internal gas pressure, sheath oxidation in air environment, stress corrosion cracking (SCC), delayed hydride cracking (DHC), and sheath splitting due to UO2 oxidation for a defective fuel. The failure by creep rupture, SCC or DHC is in the form of small cracks or punctures. The failure by sheath oxidation or sheath splitting due to UO2 oxidation results in a gross sheath rupture. The second step was to examine the technical bases of all modules of the in-house code, identify and extend the ranges of all modules to required operating ranges. This step assessed the degradation mechanisms for the fuel integrity. The objective of this assessment is to predict the probability of sheath through-wall failure by a degradation mechanisms as a function of the sheath temperature during dry storage. Further improvements being considered include upgrades of the analysis module to achieve sufficient accuracy in key output parameters. The emphasis in the near future will be on validation of the inhouse code according to a rigorous and formal methodology. The developed models provide a platform for research and industrial applications, including the design of fuel behavior experiments and prediction of safe operating margins for CANDU spent fuel.

REDUCTION OF EMISSIONS WITH PROPANE ADDITION TO A DIESEL ENGINE

J. LEE,S. CHOI,H. KIM,D. KIM,H. CHOI,민경덕 한국자동차공학회 2013 International journal of automotive technology Vol.14 No.4

Recent studies on dual-fuel combustion in compression–ignition (CI) engines, also known as diesel engines,fall into two categories. In the first category are studies focused on the addition of small amounts of gaseous fuel to CI engines. In these studies, gaseous fuel is regarded as a secondary fuel and diesel fuel is regarded as the main fuel for combustion. The objectives of these studies typically involve reducing particulate matter (PM) emissions by using gaseous fuel as a partial substitution for diesel fuel. However, the addition of gaseous fuel raises the combustion temperature, which increases emissions of nitrogen oxides (NOx). In the second category are studies focused on reactivity-controlled compression–ignition (RCCI) combustion. RCCI combustion can be implemented by early diesel injection with a large amount of low-reactivity fuel such as gasoline or gaseous fuel. Although RCCI combustion promises lower NOx and PM emissions and higher thermal efficiency than conventional diesel combustion, it requires a higher intake pressure (usually more than 1.7 bars) to maintain a lean fuel mixture. Therefore, in this study, practical applications of dual-fuel combustion with a low air–fuel ratio (AFR),which implies a low intake pressure, were systemically evaluated using propane in a diesel engine. The characteristics of dualfuel combustion for high and low AFRs were first evaluated. The proportion of propane used for four different operating conditions was then increased to decrease emissions and to identify the optimal condition for dual-fuel combustion. Although the four operating conditions differ, the AFR was maintained at 20 (Φ approximately equal to 0.72) and the 50% mass fraction burned (MFB 50) was also fixed. The results show that dual-fuel combustion can reduce NOx and PM emissions in comparison to conventional diesel combustion.