• Title/Summary/Keyword: 24-month cycle

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Loading pattern design and economic evaluation for 24-month cycle operation of OPR-1000 in Korea

  • Jeongmin Lee;Hyun Chul Lee
    • Nuclear Engineering and Technology
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    • v.55 no.3
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    • pp.1167-1180
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    • 2023
  • Due to the tightened regulatory environment since the Fukushima accident, the capacity factor of Korean nuclear power plants has been declining since 2011. To overcome this circumstance, a shift from 18-month to 24-month cycle operation is being considered in Korea. Therefore, in this study, loading patterns(LPs) for 24-month cycle operation of the Korean standard nuclear power plant(OPR-1000) are suggested and economic evaluations are performed. A single-zone LP with 89 fresh fuels was evaluated to be optimal for 24-month operation of OPR-1000 in terms of economic gain. The 24-month operation of OPR-1000 with this LP gives a profit of 7.073 million dollars per year compared to 18-month operation.

Physics study for high-performance and very-low-boron APR1400 core with 24-month cycle length

  • Do, Manseok;Nguyen, Xuan Ha;Jang, Seongdong;Kim, Yonghee
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.869-877
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    • 2020
  • A 24-month Advanced Power Reactor 1400 (APR1400) core with a very-low-boron (VLB) concentration has been investigated for an inherently safe and high-performance PWR in this work. To develop a high-performance APR1400 which is able to do the passive frequency control operation, VLB feature is essential. In this paper, the centrally-shielded burnable absorber (CSBA) is utilized for an efficient VLB operation in the 24-month cycle APR1400 core. This innovative design of the VLB APR1400 core includes the optimization of burnable absorber and loading pattern as well as axial cutback for a 24-month cycle operation. In addition to CSBA, an Er-doped guide thimble is also introduced for partial management of the excess reactivity and local peaking factor. To improve the neutron economy of the core, two alternative radial reflectors are adopted in this study, which are SS-304 and ZrO2. The core reactivity and power distributions for a 2-batch equilibrium cycle are analyzed and compared for each reflector design. Numerical results show that a VLB core can be successfully designed with 24-month cycle and the cycle length is improved significantly with the alternative reflectors. The neutronic analyses are performed using the Monte Carlo Serpent code and 3-D diffusion code COREDAX-2 with the ENDF/B-VII.1.

Doenjang Extract Has Anticancer Activity and Induces Apoptosis in AGS Human Gastric Adenocarcinoma

  • Hwang, Kyung-Mi;Lee, Jeong-Min;Park, Kun-Young
    • Preventive Nutrition and Food Science
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    • v.10 no.2
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    • pp.167-171
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    • 2005
  • The anticancer and apoptotic effect of chloroform extract from 24 month-fermented doenjang were investigated in AGS human gastric adenocarcinoma cells. The chloroform extract of 24 month-fermented doenjang inhibited the AGS gastric cancer cell growth in a dose-dependent manner. It has been confirmed by observing the cell distribution under inverted microscope. Approximately, 48 hour treatment of $100\;{\mu}g/mL$ doenjang extract inhibited AGS cancer cell growth by $76.7\%$, respectively. The growth inhibition may be caused by apoptosis of AGS cancer cells after 48 hour treatment of 24 month-fermented doenjang extract. It has been demonstrated by cell cycle arrest that revealed the shift from $G_2+M\;to\;G_0+G_1$ phase and the formation of apoptotic bodies. The fermentation period playa critical role in cell cycle arrest, in which 24 month-fermented doenjang extract was more effective than 12 month-fermented doenjang extract. The treatment of 24 month-fermented doenjang extract for 48 hours has induced intercellular Bax and decreased Bcl-2 level, indicating that it may regulate the expression level of Bax/Bcl-2 proteins. Thus, 24 month-fermented doenjang extract seems to have anticancer effect via cancer cell growth inhibition induced by apoptosis process.

Feasibility of combinational burnable poison pins for 24-month cycle PWR reload core

  • Dandi, Aiman;Lee, MinJae;Kim, Myung Hyun
    • Nuclear Engineering and Technology
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    • v.52 no.2
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    • pp.238-247
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    • 2020
  • The Burnable Poison (BP) is very important for all Light Water Reactors in order to hold-down the initial excess reactivity and to control power peaking. The use of BP is even more essential as the excess reactivity increases significantly with a longer operation cycle. In this paper a feasibility study was conducted in order to investigate the benefits of a new combinational BP concept designed for 24-month cycle PWR core. The reference designs in this study are based on the two Korean fuel assemblies; 17 × 17 Westinghouse (WH) design and 16 × 16 Combustion Engineering (CE) design. A modification was done on these two designs to extend their cycle length from 18 months into 24 months. DeCART2D-MASTER code system was used to perform assembly and core calculations for both designs. A preliminary test was conducted in order to choose the best BP suitable for 24-month as a representative for single BP concept. The comparison between the results of two concepts (combinational BP concept and single BP concept) showed that the combinational BP concept can replace the single BP concept with better performance on holding down the initial excess reactivity without violating the design limitations.

A Study on the Hog Price Patterns and It's Forecasting Model (돼지가격(價格)의 변동(變動)패턴과 예측모형(豫測模型)에 관(關)한 연구(硏究))

  • Kim, Chul Ho
    • Korean Journal of Agricultural Science
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    • v.12 no.2
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    • pp.341-348
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    • 1985
  • This study aims at analysis hog cycles and seasonal price patterns, and at develop the procedure for price forecasting based on the relative price ratios by farmers. Seasonal price patterns have been a persistent feature of hog markets. Some month have historically high price and other months historically low price. Hog price tend to be high in Feb, May, June, Sept, winter (Nov. to Jan.) and tend to be low in the other months. There have been four price cycles for 12 years, 1972-1984, the length of the hog price cycle has varied from 24 month to 42 months, with the irregular frequency. The increasing period of the price cycle lasted 23 months and the decreasing period of the price cycle lasted 13 months. Tables 2, 3, 4 in this study show average hog price ratios and the number of times price fall, rose for one, two, and three months ahead of each calendar month.

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Radiation Exposure Reduction in APR1400

  • Bae, C.J.;Hwang, H.R.;Matteson, D.M.
    • Journal of Radiation Protection and Research
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    • v.28 no.2
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    • pp.127-135
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    • 2003
  • The primary contributors to the total occupational radiation exposure in operating nuclear power plants are operation and maintenance activities doting refueling outages. The Advanced Power Reactor 1400 (APR1400) includes a number of design improvements and plans to utilize advanced maintenance methods and robotics to minimize the annual collective dose. The major radiation exposure reduction features implemented in APR1400 are a permanent refueling pool seal, quick opening transfer tube blind flange, improved hydrogen peroxide injection at shutdown, improved permanent steam generator work platforms, and more effective temporary shielding. The estimated average annual occupational radiation exposure for APR1400 based on the reference plant experience and an engineering judgment is determined to be in the order of 0.4 man-Sv, which is well within the design goal of 1 man-Sv. The basis of this average annual occupational radiation exposure estimation is an eighteen (18) month fuel cycle with maintenance performed to steam generators and reactor coolant pumps during refueling outage. The outage duration is assumed to be 28 days. The outage work is to be performed on a 24 hour per day basis, seven (7) days a week with overlapping twelve (12) hour work shifts. The occupational radiation exposure for APR1400 is also determined by an alternate method which consists of estimating radiation exposures expected for the major activities during the refueling outage. The major outage activities that cause the majority of the total radiation exposure during refueling outage such as fuel handling, reactor coolant pump maintenance, steam generator inspection and maintenance, reactor vessel head area maintenance, decontamination, and ICI & instrumentation maintenance activities are evaluated at a task level. The calculated value using this method is in close agreement with the value of 0.4 man-Sv, that has been determined based on the experience aid engineering judgement. Therefore, with the As Low As Reasonably Achievable (ALARA) advanced design features incorporated in the design, APR1400 design is to meet its design goal with sufficient margin, that is, more than a factor of two (2), if operated on art eighteen (18) month fuel cycle.

LEU+ loaded APR1400 using accident tolerant fuel cladding for 24-month two-batch fuel management scheme

  • Husam Khalefih;Taesuk Oh;Yunseok Jeong;Yonghee Kim
    • Nuclear Engineering and Technology
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    • v.55 no.7
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    • pp.2578-2590
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    • 2023
  • In this work, a 24-month two-batch fuel management strategy for the APR1400 using LEU + has been investigated, where enrichments of 5.9 and 5.2 w/o are utilized in lieu of the conventional 4-5 w/o UO2 fuel. In addition, an Accident Tolerant Fuel (ATF) clad based on the swaging technology is applied to APR1400 fuel assemblies. In this special ATF clad design, both outer and inner SS316 layers protect the conventional zircaloy clad. Erbia (Er2O3) is introduced as a burnable absorber with two-fold goals to lower the critical boron concentration in the long-cycle LEU + loaded core as well as to handle the LEU + fuel in the existing front-end fuel facilities without renewing the license. Two types of fuel assemblies with different loading of gadolinia (Gd2O3) are considered to control both the reactivity and the core radial power distribution. The erbia burnable absorber is uniformly admixed with UO2 in all fuel pins except for the gadolinia-bearing ones. In this study, two core designs were devised with different erbia loading, and core performance and safety parameters were evaluated for each case in comparison with a core design without any burnable absorbers. The core analysis was done using the two-step method. First, cross-sections are generated by the SERPENT 2 Monte Carlo code, and the 3-D neutronic analysis is performed with an in-house multi-physics nodal code KANT.

Information Systems for Organizational Agility: Action Research on Resource Scheduling at the Universidad de Chile

  • Seo, Dong Back;La Paz, Ariel I.;Miranda, Jaime
    • Asia pacific journal of information systems
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    • v.24 no.4
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    • pp.417-441
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    • 2014
  • Organizations need to exhibit characteristics of agility to stay ahead of their competitors and to survive in dynamic environments. One major concern for organizations is how to implement Information Systems (ISs) to enhance their agility. Organizations tend to spend too many resources to change their entire IS instead of only the components that cause problems without exactly knowing whether it enables or suppress organizational agility. To address these shortcomings and practical issues, we provide a framework to assess organizational agility and to diagnose a problem related to IS. By applying this prototype of the Agility Framework, we were able to diagnose a problem that the department of Management Control and Information Systems at the Universidad de Chile had and planned actions for them to improve its organizational agility with a course scheduling system, eClasSkeduler. This action research, which took more than 25-month for the first cycle, further develops the Agility Framework, which not only provides a way to link IS with organizational functions but also illustrates how to use it to diagnose a situation and plan actions for improving organizational agility through an information system.

Studies on the plasma progesterone concentrations for pregnancy diagnosis in Che-ju native mare (제주재래마(濟州在來馬)의 혈중(血中) progesterone농도측정(濃度測定)에 의한 임신진단(姙娠診斷)에 관한 연구(硏究))

  • Chang, Deuk-Jee;Yang, Ki-Chun;Kim, Jung-Kye;Kang, Byong-Kyu;Choi, Han-Sun;Son, Chang-Ho
    • Korean Journal of Veterinary Research
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    • v.31 no.4
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    • pp.529-534
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    • 1991
  • Plasma progesterone concentrations were measured from 97 Che-ju native mares throughout the estrous cycle, Day 20 to 23, 5 to7 months of pregnancy, and gestation period (<1 to 7 months) using the radioimmunoassay techniques for pregnancy diagnosis. Plasma progesterone concentrations during the estrous cycle were the lowest (<1.0ng/ml) at estrus, remained high from 9 to 18 days (3.7~7.6ng/ml) and drastically decreased thereafter to reach minimal concentrations at the next estrus. Plasma progesterone concentrations at Day 21 to 24 were a significantly different between in pregnant mares (>5.7ng/ml) and in non-pregnant mares (<1.0ng/ml). The accuracy of the pregnancy diagnosis based on plasma progesterone concentrations at Day 20 to 23 was 86.7% for positive and 100% for negative, whereas on 5 to 7 months was 66.7% for positive and 71.0% for negative, respectively. Plasma progesterone concentrations during the gestation period(1 to 7 months) increased after 1 month of pregnancy, with peak concentrations(>8.0ng/ml) occurring between 60 to 100 days of pregnancy, and decreased below 1.7ng/ml after 6 months of pregnancy.

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Assessment of Natural Radiation Exposure by Means of Gamma-Ray Spectrometry and Thermoluminescence Dosimetry (감마선분광분석(線分光分析) 및 열형광검출법(熱螢光檢出法)에 의한 자연방사선(自然放射線)의 선량측정연구(線量測定硏究))

  • Jun, Jae-Shik;Oh, Hi-Peel;Choi, Chul-Kyu;Oh, Heon-Jin;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
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    • v.10 no.2
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    • pp.96-108
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    • 1985
  • A study for the assessment of natural environmental radiation exposure at a flat and open field of about $10,000m^2$ in area in CNU Daeduk campus has been carried out by means of gamma-ray scintillation spectrometry and thermoluminescence dosimetry for one year period of time from October 1984. The detectors used were 3'${\phi}{\times}$3' NaI(T1) and two different types of LiF TLD, namely, chip sealed in plastic sheet which tightly pressed on two open holes of a metal plate and Teflon disk. Three 24-hour cycles of in-situ spectrometry, and two 3-month and one 1-month cycles of field TL dosimetry were performed. All the spectra measured were converted into exposure rate by means of G(E) opertaion, and therefrom exposure rate due to terrestrial component of environmental radiation was figured out. Exposure rate determined by the spectrometry was, on average, $(10.54{\pm}2.96){\mu}R/hr$, and the rates of $(12.0{\pm}3.4){\mu}R/hr$ and $(11.0{\pm}3.6){\mu}R/hr$ were obtained from chip and disk TLD, respectively. Fluctuations in diurnal variation of the exposure rate measured by the spectrometry were noticeable sometime even in a single cycle of 24 hours. It is concluded that appropriately combined use of TLD with iu-sitn gamma-ray spectrometry system can give more accurate and precise measure of environmental radiation exposure, and further study for more adequate and sensitive TLD for environmental dosimetry, including improvement and elevation of accuracy in data assessment through inter-laboratory or international intercomparison is necessary.

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