Power Plants In Korea Research Articles

국내 모 유연탄 발전소의 석탄회 매립 염호수 내 미량원소 농집에 대한 지구화학적 연구

국내 모 유연탄 발전소의 석탄회 매립 염호수 내 미량원소 농집에 대한 지구화학적 연구

화력발전소 배관시스템의 운전 및 기후조건에 따른 에너지절감에 관한 시뮬레이션

Most of steam power plants in Korea are using the method of heating the feed water whenever the ambient temperature around the power plant area below <TEX>$5^{\circ}C$</TEX> to prevent freezing water flowing in the pipe in winter time. But this kind of heat supplying system is not useful to save energy. If we take the method that the temperature of the each pipe is controled by direct measure of temperature by attaching sensor on the outside surface of the feed water tubes, then we can expect that a plenty of energy can be saved. In this study, the computer simulation is used to compare the energy consumption loads of both systems. Energy saving rate is calculated for the location of Incheon area in winter season. Four convection heat transfer coefficients for the ambient air and three initial flowing water temperature inside the tube were used. The result shows that the temperature control system using sensor represents more than 95% of energy saving rate in Incheon area. Even in the severe January weather condition, the energy saving rate is almost 75% in two days basis and even 83% in one day basis.

Test Operation Results of the 10 MWe-scale Dry-sorbent CO2 Capture Process Integrated with a Real Coal-fired Power Plant in Korea

Abstract The ground-breaking ceremony of the10 MWe-scale dry-sorbent CO2 capture process was held in August 2012 and the construction was finished in October 2013. It was integrated with a 500 MW power plant and used a slip-stream of that, located at the Hadong coal-fired power plant (Unit #8), Korea Southern Power Company. From October 2013, Korea Institute of Energy Research (KIER), Korea Southern Power Company, and KC Cottrell have executed the test operations in order to find out the optimal operational conditions and several modification parts to achieve the target project goals of the 10 MWe-scale dry-sorbent CO2 capture technology. The dry-sorbents have been developed by KEPCO Research Institute and massively produced and supplied by TODA-ISU, which consists of 35 wt.% of active components for the CO2 sorption and 65 wt.% of supporters for the mechanical strength. The some portions of the dry-sorbents have been tested at the 0.5 MWe-scale dry-sorbent CO2 capture process in order to analyze the sorbent performance through the two-week operation campaign in June 2013. During the test operations, the 10 MWe-scale dry-sorbent CO2 capture process has been divided into four parts such as a sorbent handling part, a flue gas pre-treatment part, a main reactor part, a utility (steam, cooling water, and instrument air) part. In the sorbent handling part, the sorbent feeding system has been tested so that the sorbent has automatically fed to the reactor system and conversely fed to the sorbent silo. In the flue gas pre-treatment part, main blower, the secondary flue gas desulfurization, and the moisture control of the flue gas have been tested. In the main reactor part, the solid hold-up in the carbonation reactor, the solid circulation rate, control concept, and the reaction performance of the sorbent have been tested. In the utility part, steam supply, cooling tower operation, and instrument air compressor operation have been tested. The test operations will be done on January 2014 and the long-term continuous operations will be performed from early March 2014. We plan to continuously operate the 10 MWe-scale dry-sorbent CO2 capture process from the second quarter of this year, to analyze the economics of the dry-sorbent CO2 capture technology based on the operational results, and to finish FEED of the 300 MWe-scale dry-sorbent CO2 capture technology until the end of the third quarter of this year.

원전 증기발생기 와전류검사 장치의 전기적 특성 측정

원전 증기발생기는 원자로 냉각재 계통에서 발생한 열에너지를 터빈 계통의 주급수에 전달하여 터빈을 회전시키기 위한 증기를 생산하는 일종의 열교환기이다. 증기발생기 전열관의 손상은 증기발생기의 구조적 및 누설 건전성 유지 능력을 저해시키기 때문에 주기적으로 와전류검사를 수행하여 전열관의 건전성을 평가한다. 증기발생기 전열관의 건전성 평가는 보통 원자로 연료 재장전 기간 중에 수행된다. 현재 국내 증기발생기 전열관에 적용되는 와전류검사는 KEPIC 및 ASME 코드 요건에 따라 수행되며, 와전류검사 수행에 필요한 검사 시스템은 와전류검사 장치와 수집된 신호를 평가하기 위한 평가 프로그램으로 구성된다. 검사에 적용되는 와전류검사 시스템을 구성하는 핵심기기인 와전류검사 장치는 ASME 및 KEPIC 코드에서 총 고조파 왜곡율, 입출력 임피던스, 증폭기 직선성 및 안정성, 위상 직선성, 대역폭 및 복조필터 응답, 디지털 변환, 채널 간섭 등과 같은 전기적 특성을 측정하도록 규정하고 있다. 이에 따라 본 논문에서는 국내 최초로 개발한 원전 증기발생기 와전류검사 장치의 전기적 특성 측정을 위한 ASME 및 KEPIC 코드 요건을 설명하고, 이 요건에 따른 증기발생기 와전류검사 장치의 전기적 특성의 측정 결과를 제시하였다. A steam generator in nuclear power plant is a heatexchager which is used to convert water into steam from heat produced in a nuclear reactor core, and the steam produced in steam generator is delivered to the turbine to generate electricity. Because of damage to steam generator tubing may impair its ability to adequately perform required safety functions in terms of both structural integrity and leakage integrity, eddy current testing is periodically performed to evaluate the integrity of tubes in steam generator. This assessment is normally performed during a reactor refueling outage. Currently, the eddy current testing for steam generator of nuclear power plant in Korea is performed in accordance with KEPIC & ASME Code requirements, the eddy current testing system is consists of remote data acquisition unit and data analysis program to evaluate the acquired data. The KEPIC & ASME Code require that the electrical properties of remote data acquisition unit, such as total harmonic distortion, input & output impedance, amplifier linearity & stability, phase linearity, bandwidth & demodulation filter response, analog-to-digital conversion, and channel crosstalk shall be measured in accordance with the KEPIC & ASME Code requirements. In this paper, the measurement requirements of electrical properties for eddy current testing instrument described in KEPIC & ASME Code are presented, and the measurement results of newly developed eddy current testing instrument by KHNP(Korea Hydro & Nuclear Power Co., LTD) are presented.

Seasonal and spatial variations in nematode assemblages affected by thermal influence of nuclear power plant in Korea (East Sea, Pacific Ocean)

The effects of the thermal discharge from a coastal nuclear power plant on the spatial and seasonal variability of nematode assemblages were investigated in the Gori coastal waters of the southern East Sea. Taxonomic and functional approaches were taken to describe the assemblage structure and relate it to the abiotic environment based on a sampling scheme involving three stations and four seasons. The analysis of the nematode communities suggested that heated effluent influenced the assemblage structure or the spatial distribution of the taxa studied. The abundance of the nematodes differed significantly among seasons and stations and the numbers of species also differed significantly between stations. The seasonal variation was greater in winter and summer than in spring and autumn. The numbers of species and their abundances were highest at station 3 (impact station), attributable to the increased bottom temperature. However, the functional diversity of the assemblages did not change notably between stations or seasons. Species such as Sabatieria sp. (34%), Linhystera sp. (18%) and Parodontophora sp. (11%) were usually dominant in all seasons and at all stations. Parodontophora sp. displayed a significantly negative correlation with the bottom temperature (P<0.05). These results indicate that the nematode species composition was significantly affected by the bottom temperature.

The Relationship of Science Knowledge, Attitude and Decision Making on Socio-scientific Issues: The Case Study of Students’ Debates on a Nuclear Power Plant in Korea

The purpose of this study was to investigate the relationship of students’ understanding of science knowledge, attitude and decision making on socio-scientific issues (SSI), especially on the issues of nuclear energy in Korea. SSI-focused instructions were developed to encourage students to understand and reflect on knowledge, attitude and decision making on nuclear energy in the current society. Eighty-nine students attended the instruction and participated in pre and post questionnaires to understand their understandings of nuclear energy. In this study, science knowledge was categorized into content and contextual knowledge, attitude consisted of images, safety, risk, potential, benefits and future roles, and decision making section included preference and alternative about lifetime extension of nuclear power plant. The results of questionnaires were analyzed by correlation, cross-tabulation and regression. As a result, while students’ understandings of science knowledge were significantly improved throughout the instruction, they maintained similar attitude and decision making on the issue. Regarding the relationship of the three domains, attitude showed some degree of connection to decision making whereas science knowledge did not show a significant relationship to decision making. This finding challenges SSI teaching in content-based science curriculum and classroom. Reflection and implications on the way of teaching SSI in the classroom were discussed further in this paper.

원전 연료집합체의 손상, 변형 및 이물질 검사시스템 개발에 관한 연구

Screen inspection system applied vision and laser scan technology which detect foreign materials caused fuel rod to be damaged, and which inspect fuel rod damage, bowing, distortion and grid damages, was developed to secure reliability and reproductivity of inspection method for nuclear fuel assembly during outage. In further, datum of inspection results will be continuously monitored and given understand the pattern of bowing and distorting for fuel assembly in reactor. Understanding of the pattern will be key technical information to avoid grid demage might be happened during refueling outage and provides important data base for safe operation of nuclear power plant in Korea and world wide.

A Study on the Measurement of Whole-Body Vibration in Some Coal-fired Power Plant Workers

Objective: This study measured and evaluated the characteristics of the whole body vibration experienced in some coal-fired power plant in Korea. Background: Few studies have been carried out in Korea about the effects of whole body vibration of power plants on humans. Method: The evaluation scheme suggested by the Law of Noise and Vibration Control was applied. Results: It was found that 28.9% of total measurement points were above the limit suggested by the law. Conclusion: Many workers are exposed to whole body vibration during their job completion, and more efforts should be applied to prevention and control of the plat vibration.

석탄 잔사회 및 바닥재가 포함된 인공경량골재의 발포특성에 미치는 활성탄소의 영향

화력발전소에서 배출되는 석탄 바닥재 및 잔사회는 재활용이 힘든 폐자원이어서 주로 매립 처분되고 있다. 본 연구에서는 국내 화력발전소에서 배출된 석탄 잔사회, 바닥재 그리고 준설토를 혼합하여 인공골재를 제조하고, 실험인자가 골재의 발포거동 및 물성에 미치는 영향을 분석하였다. 특히 미연탄소가 많이 포함되어 있는 잔사회에 대하여 하소 처리를 한 뒤, 인위적으로 활성탄소를 첨가함으로서 하소유무 및 활성탄소 첨가량이 인공골재의 발포특성에 미치는 영향을 조사하였다. 이를 위해 인공골재의 부피비중 및 흡수율 값을 시편의 미세구조 관찰 결과와 연계하여 고찰함으로서, 잔사회의 재활용율 제고에 일조하고자 하였다. The coal bottom ash and reject ash discharged from a coal-fired power plant are difficult to recycle so most of them are mainly landfill-disposed. In this study, the artificial aggregate were produced using reject ash, bottom ash and dredged soil emitted from the coal-fired power plant in Korea and the effect of experimental factors on the bloating behavior and the properties of the aggregates were analyzed. In particular, a lot of unburned carbon in the reject ash was removed by calcination and the activated carbon was added to batch powders then the dependence of those process upon bloating properties of artificial aggregate were investigated. For this purpose, the specific gravity and water absorption values of artificial aggregates were investigated in conjunction with microstructural observations. This study could contribute to increase the recycling rate of the reject ash.

RETScreen을 활용한 조력발전 개발사업 경제성 분석 - 아산만 조력발전소 사례를 중심으로 -

본 연구에서는 타 신재생에너지에 비해 영구적으로 사용이 가능하며, 예측가능한 대용량의 균질 에너지 생산이 가능하며, 발전효율이 높은 조력에너지를 활용하기 위한 조력발전 개발사업에 대한 경제적 타당성을 분석한다. 이를 위해, 세계적으로 청정에너지 프로젝트의 경제성 및 민감도 분석을 위해 널리 활용되고 있는 캐나다 천연자원부 산하의 CANMET 에너지기술센터에서 개발한 RETScreen을 활용하였다. 분석 대상 조력발전 개발사업과 관련된 자료가 총괄적으로 존재한다는 한계점에도 불구하고, RETScreen의 기능을 이용함으로써 기획단계에서 사업의 경제적 타당성을 검토하기에 충분한 예측력을 가진 분석 결과를 도출할 수 있었다. 경제성 및 민감도 분석 결과, 사업과 직접적으로 관련된 현금의 흐름만을 고려할 경우, 국내에서도 조력발전 개발사업은 충분한 경제성을 갖고 있으며 탄소배출권 시세와 전력 판매단가의 상승폭에 따라 조력발전 사업의 경제성은 더욱 높아질 수 있을 것으로 예측되었다. 본 연구의 결과를 바탕으로, 자연환경을 파괴하지 않는다는 전제 아래 조력발전소의 건설이 활성화된다면, 가까운 미래에 닥쳐올 에너지 문제를 슬기롭게 해결할 수 있을 것으로 기대된다. In this research, we analyse the economic feasibility of a tidal power plant project which can efficiently generate mass, permanent, predictable, and homogeneous electric power. For the economic feasibility analysis, we used the RETScreen that is developed at the CANMET Energy Technology Center in Natural Resources Canada and widely utilized for analysing the economic feasibility and sensitivity of clean energy projects. Results from the feasibility and sensitivity analysis showd that the tidal power plant project in Korea has a enough economic feasibility, and its feasibility increases more as certified emission reductions price and electricity unit price increase. Based on the results from the feasibility study, we can solve the energy problems to be come in near future by constructing the tidal power plants in Korea more aggressively.

Design modification of a feedwater heater impingement baffle to mitigate shell wall thinning by flow acceleration corrosion

The feedwater heaters of many power plants can experience severe wall thinning damage, which accelerates as the plant ages. Several nuclear power plants in Korea have undergone this wall thinning damage around the impingement baffle inside feedwater heaters installed downstream of the turbine extraction stream line. At the baffle point, the extracted steam from the turbine exists as a two-phase fluid at high temperature, high pressure, and high velocity. Since it flows in the reverse direction after impinging the impingement baffle, the shell walls of feedwater heaters may be affected by flow acceleration corrosion. This paper describes a comparison of a numerical analysis using the FLUENT code and downscaled experimental data in an effort to determine the root causes of shell wall thinning of feedwater heaters. The numerical analysis and experimental data were also confirmed by actual wall thicknesses as measured by flow visualization. To compare the degree of shell wall thinning, a test of the mitigation rate on squared-type impingement baffle plates compared with the mitigation rate of other types of impingement baffle plates (squared, curved, mitigating, and multi-hole type) was done inside the shell of a feedwater heater. This paper describes the experimental procedures and the numerical analysis of these comparison data. These experiments were done using conditions similar to those found in a real feedwater heater. Flow visualization was done in order to verify the experimental results and the numerical analysis. From the comparison of the results of the local velocity profiles and the wall-thinning measurements, this study shows that mitigating type and multi-hole type impingement baffle plates are more effective than other baffle plates in preventing decreases in pressure concentration and pressure value.

Radiological effluents released and public doses from nuclear power plants in Korea

As of the end of 2010, there were 20 commercially operating nuclear reactors in Korea. Releases of radioactive effluents from nuclear power plants (NPPs) have increased continuously; the total radioactivity of effluent amount released in 2010 was 547.12 TBq. From 2001 to 2010, the annual average radioactivity of gaseous and liquid effluents per reactor was 11.61 TBq for pressurised water reactors and 118.12 TBq for pressurised heavy water reactors. Most of the radioactivity from gaseous and liquid effluents came from tritium. Based on the results of release trends and analyses, the characteristics of effluents have been investigated to improve the management of radioactive effluents from NPPs.

전기적 열제어 시스템을 사용한 에너지 소비량 감소에 관한 연구

Most of steam power plant in Korea are heating the feed water system to prevent freezing water flowing in the pipe in winter time. The heating system is operated whenever the ambient temperature around the power plant area below 5 degree Centigrade. But this kind of heat supplying system cause a lot of energy consuming. If we think about the method that the temperature of the each pipe is controled by attaching the temperature measuring sensor like RTD sensor and heat is supplied only when the outer surface temperature of the pipe is under 5 degree Centigrade, then we can save a plenty of energy. In this study, the computer program package for simulation is used to compare the energy consumption load of both systems. Energy saving rate is calculated for the location of Youngweol area using the data of weather station in winter season, especially the January' severe weather data is analyzed for comparison. Various convection heat transfer coefficients for the ambient air and the flowing water inside the pipe was used for the accurate calculation. And also the various initial flowing water temperature was used for the system. Steady state analysis is done previously to approximate the result before the simulation. The result shows that the temperature control system using RTD sensor represents the high energy saving effect which is more than 90% of energy saving rate. Even in the severe January weather condition, the energy saving rate is almost 60%.

A Preliminary Study on the Communication Effect on Team Performance in Main Control Room of SMART

Objective: The aim of this study is to investigate the attributing factors influencing team performance. Background: Technically, it is necessary that operators adapt themselves to computerized and advanced techniques to operate the main control rooms safely in nuclear power plant in Korea. The more main control rooms are digitalized, the more important for operators to have high team performance it is. Method: This paper analyzes team process through literatures review and elicits team performance shaping factor. Especially, the objective of this research is to elicit communication using common team performance shaping factors. Results: This study has found communication through team performance shaping factors in Main Control Room of the SMART. Conclusion: This paper can offer a starting point for team communication, which can use team performance shaping factor framework that are emerging in these new nuclear power plant. Application: As a result, I expect that the evaluation communication for MCR operator's team performance will lead the operating techniques in nuclear power industry internationally.

Effect of Sintering Conditions on the Bloating Property of Artificial Aggregates Made from Dredged Soil

The artificial aggregates were fabricated by two sintering methods to recycle the dredged soil produced at thermal power plant in Korea. The first one is the direct sintering method in which the green body is to put into the furnace of preheated at the desired temperature, and the other is the temperature-rising sintering method in which the green body is to put into the furnace of 800~900 oC, heated with a heating rate of 15 °C/min to the final sintering temperature. The aggregate manufactured by the direct sintering method showed the highest bloating behavior than that of the temperature-rising method. To provide the holding time in the input step was to decrease the bloating behavior in the temperature-rising sintering method. The water absorption for the all aggregates was decreased with sintering temperature, and the values of aggregates made by direct sintering was higher than that of the temperature-rising sintering method. The aggregate made of dredged soil by using various sintering methods had the specific gravity of 0.9~1.8 and water absorption of 3~14 %, and so could be applicable for many fields such as civil, environmental, and agricultural engineering fields.

Observation of Reactor Electron Antineutrino Disappearance at RENO

The Reactor Experiment for Neutrino Oscillation (RENO) has obtained a definitive measurement of the smallest neutrino mixing angle of θ13 by observing the disappearance of electron antineutrinos emitted from a nuclear reactor, excluding the no-oscillation hypothesis at 4.9 σ. From the deficit, the best fit value of sin22θ13 is obtained as 0.113±0.013(stat.)±0.019(syst.) based on a rate-only analysis. Antineutrinos from six 2.8 GWth reactors at the Yonggwang Nuclear Power Plant in Korea, are detected by two identical detectors at 294 m and 1383 m, respectively, from the reactor array center. In the 229 day data-taking period between 11 August 2011 and 26 March 2012, the far (near) detector observed 17102 (154088) electron antineutrino candidate events with a background fraction of 5.5% (2.7%). The ratio of observed to expected numbers of the reactor antineutrinos in the far detector is 0.920±0.009(stat.)±0.014(syst.).

The Status of the Development Project for the 10 MWe-Scale Dry-sorbent Carbon Dioxide Capture System to the real Coal-Fired Power Plant in Korea

Carbon dioxide capture system using dry regenerable K-based sorbents has been developed by Korea Institute of Energy Research (KIER) and Korea Electric Power Research Institute (KEPRI). In late 2009, we installed a 0.5 MWe-scale CO2 capture pilot plant at Hadong coal-fired power plant in Korea. The pilot plant consists of a transport fluidized-bed carbonator for CO2 sorption, cyclones for separating gas and solid, a bubbling fluidized-bed regenerator for sorbent regeneration, and a bubbling fluidized-bed sorbent cooler for sorbent cooling. The footprint of the pilot plant was 6 m x 10 m and the location of that was after Gas Gas Heater of the power plant. Until now, we have performed 100-day operation campaigns to find out the optimum operating conditions and the scale-up factors for 10 MWe-scale capture process. In the operation campaigns, several operating variables such as the moisture content in the flue gas, the solid hold-up in a carbonator, the solid circulation rate between a carbonator and a regenerator, and the reaction temperatures have been changed in order to investigate the effect of those variables on CO2 capture and to derive the scale-up factors. It has been proved that above 80% of CO2 removal for 50-hour continuous operation was possible at the optimum operating conditions.At the same time, we set the small scale unit which consists of two bubbling beds for carbonation and regeneration in order to investigate the effect of the H2O partial pressure in the regenerator on CO2 removal. The CO2 removal in the carbonator increased as the steam mole fraction in the fluidization gas of the regenerator increased, although the content of H2O, which is a product component in the regenerator, increased. We proved that the K2CO3 1.5H2O has been formed in the regenerator by the XRD analysis and TGA analysis of the regenerated sorbent. The formation of K2CO3 1.5H2O makes the carbonation reaction more active so that the CO2 removal increased. It is also verified that high-concentrated CO2 can be recovered when 100% of H2O has been introduced as a steam phase to the regenerator. Thus, we also install the steam injection line to the regenerator in the 0.5 MWe-scale pilot plant. During 100-day operation campaign, we also tested high-concentrated CO2 recovery by introducing 100% of H2O as a steam phase to the regenerator.

Simulation of release rate coefficients of fission products for debris-induced fuel failures

Two types of debris-induced fuel failures have occurred in one nuclear power plant in Korea. The first type fuel failure has occurred at a thrice-burned fuel rod, not showing a secondary hydride-induced through-crack, while the second type one at a first-burned fuel rod, showing a secondary hydride-induced through-crack. Models for pellet-to-gap and gap-to-coolant release rate coefficients of unstable fission products have been developed with the use of their primary coolant activity variations. It is found that the secondary hydride-induced defect is more effective to the unstable fission product release rate than the primary defect. In addition, the increase in the xenon activity persists for a relatively longer time due to the secondary hydride-induced fuel defect than the increase in iodine activity. The pellet-to-gap release rate coefficients become larger with the increase of the rod power and those for xenon gases are larger by a factor of 2–8 than those for iodine fission products. The gap-to-coolant release rate coefficients are strongly dependent on the size enlargement of the primary and secondary defect as well as on the extent of the pellet-to-clad contact.

An assessment of the prestress force on the bonded tendon by SI and impact signal analysis techniques

The bonded tendon has been adopted to the reactor containment building of some operating nuclear power plants in Korea and the assessment of the prestress force on the bonded tendon is very important for the evaluation of the structural integrity. The prestress force of the bonded tendon at real reactor containment building was evaluated using the SI technique and impact signal analysis technique which were developed to improve the existing indirect assessment technique. For these techniques, the strain of the reactor containment building and the stress wave velocity of the bonded tendon were measured. Both SI technique and impact signal analysis technique give the highly reliable results comparison with the existing theoretical approach. Therefore, it is confirmed that the developed techniques are very useful for the evaluation of the prestress force on the bonded tendon.

국내원전의 방사성유출물 배출현황과 특성에 대한 고찰

국내원전의 방사성유출물 배출현황과 특성에 대한 고찰