• Nuclear Engineering and Technology
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• v.27 no.6
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• pp.877-887
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• 1995

YGN 3 is the first nuclear power plant to use the Core Protection Calculator (CPC) as the core protection system and the Core Operating Limit Supervisory System (COLSS) as the core monitor-ing system in Korea. The CPC is designed to provide on-line calculations of Departure from Nucleate Boiling Ratio (DNBR) and Local Power Density (LPD) and to initiate reactor trip if the core conditions exceed the DNBR or LPD design limit. The COLSS is designed to assist the operator in implementing the Limiting Conditions for Operation (LCOs) in Technical Specifications for DNBR/Linear Heat Rate (LHR) margin, azimuthal tilt, and axial shape index and to provide alarm when the LCOs are reached. During YGN 3 initial startup testing, extensive CPC/COLSS related tests ore peformed to ver-ify the CPC/COLSS performance and to obtain optimum CPC/COLSS calibration constants at var, -ious core conditions. Most of test results met their specific acceptance criteria. In the case of missing the acceptance criteria, the test results ore analyzed, evaluated, and justified. Through the analysis and evaluation of each of the CPC/COLSS related test results, it can be concluded that the CPC/COLSS are successfully Implemented as designed at YGN 3.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.3
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• pp.400-405
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• 1998

본 논문에서는 한국형 원자력 발전소의 기준모델인 영광 3,4호기 운전원 훈련용 시뮬레이터의 모델링 절차와 ABB-CE 원전의 독특한 계통인 CPC/COLSS (Core protection Calculator/Core Operating Limit Supervisory System) 계통에 대한 모델링을 전개허고 있다. CPC/COLSS는 원자로를 포함하는 냉각재계통(NSSS)과 핵연료의 건전성을 보장하기위한 계통으로서 감시및 보호 과정에서의 계산을 디지털화시킴으로서 정확성과 함께 원자로의 안정성을 향상시킨 특색있는 계통이다. 따라서 영광 3,4호기 시뮬레이터에서는 CPC/COLSS 계통에 대한 정확한 모델링을 하여 시험을 통해 성능및 기능에 대한 검증을 마침으로서 CPC/COLSS 시뮬레이션 모델 개발이 성공적으로 되었고 영광 3,4호기 운전 특성에 맞는 시뮬레이터를 개발하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.303-308
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• 1996

영광 3,4호기 노심보호연산기(CPC)와 노심감시계통(COLSS)의 운전성 시험은 실시간 (on-line)으로 측정된 노심보호연산기 및 노심감시계통의 결과들(DNBR, LPD, DNBR 출력제한치, LHR 출력제한치)을 노심보호 연산기 및 노심 감시계통 각각의 시뮬레이터 시스템(CEDIPS/CPC FORTRAN, COLSS FORTRAN)의 계산 결과와 비교하여 그 타당성을 검증하는 것이다. 그러나 기존의 노심보호연산기 및 노심감시계통의 운전성 시험자료 취득 방법은 관측(CPC)과 상세 보고서(COLSS)에 의한 것으로 정확한 자료 취득에 어려움이 있고 많은 시간이 소요되며 또한 자료 취득시 실수유발 가능성이 높다. 따라서 본 연구에서는 발전소 전산계통(Plant Computer System)으로부터 발전소 운전 상황을 순간적으로 기록한 자료(Snapshot)를 취하여 노심보호 연산기 및 노심감시계통 운전성 시험에 필요한 자료를 자동으로 얻는 방법을 고안하였다. 또한 발전소 Snapshot으로부터 필요한 자료를 자동으로 얻어내기 위하여 컴퓨터 프로그램(CODAP)도 개발하였다. 본 연구에서 고안된 방법은 영광 3호기 1주기 CPC/COLSS 운전성 시험에서 검증이 되어 영광4호기 1주기에 적용하였고, 이후의 후속기에도 적용할 예정이다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.508-513
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• 1997

One of the moot important constants to be Installed In COLSS, a monitoring system in CE typed reactors, is ROPM which would limit the operating space. This static ROPM was calculated from digital transient analysis assuming that every design basis transient was initiated from the most severe initial condition combination (LCO). Once It could be assured that core condition would not be located at none other than LCO, this static ROPM could be replaced with dynamic ROPM calculated at that condition and the dynamic ROPM would be definitely less than the static ROPM. In order to do, It must be required to calculate the transient discrete sensitivity parameters and parameters change distribution. The purpose of this report is just to propose the enlargement method for thermal margin.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.1085-1086
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• 2005

• Nuclear Engineering and Technology
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• v.23 no.3
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• pp.316-320
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• 1991

The Core Operating Limit Supervisory System (COLSS) is digital computer based on-line monitoring system that is designed to assist the operator in monitoring of the Limiting Conditions for Operation. A current COLSS calculates axial power distribution based on in-core detector signals using 5th order Fourier series method. It was found that the 5th elder Fourier series method was not accurate for certain axial power shapes, especially saddle power shapes, resulting in thermal margin decrease. A cubic spline synthesis was applied to the COLSS in order to improve the axial power distribution monitoring for the various axial power shapes. The results showed that the cubic spline synthesis simulated more accurately the axial power shapes, up to 5% in RMS errors, compared to those of the Fourier series.

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.148-153
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• 1993

A fifth-order Fourier series technique is applied in Core Operating Limit Supervisory System (COLSS) to construct the on-line core average axial power shape from in-core detector signals because of its simplicity and fast computation. Such a synthesizing accuracy depends on number of Fourier series modes and axial boundary conditions. COLSS currently uses the five-mode Fourier series technique which utilizes the five axially located fixed in-core detector signals and a constant axial boundary condition. Therefore, the constant axial boundary condition should be appropriately chosen based on the evaluation of its effect on the accuracy of the on-line calculations. The four cases of axial buckling (0.75, 0.8, 0.9 and 1.0) were examined for Yonggwang Nuclear Units 3&4 as the axial boundary conditions in this paper. The core average axial power shapes and the operating margins were compared for each case to determine the optimal constant axial buckling. The axial buckling of 0.9 was found to be the optimal value.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.555-561
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• 1995

This paper examines the applicability of the modified Borresen's coarse-mesh method(MBSN) to the core power distribution monitoring program development for the Yonggwang nuclear power plant unit 3(YGN 3) which uses fixed incore detectors for monitoring core power distribution. In so doing the modified Borresen's coarse-mesh equations are solved with core internal boundary conditions provided by the fixed incore detectors and three-dimensional core power distributions are com puted for the first-cycle core of the YGN 3 PWR. The results are compared with predictions of the COLSS(Core Operating Limit Supervisory System) which is the axial power shape monitoring program of the YGN 3. It is shown that the modified Borresen's method can reproduce the core axial power shape more closely than the COLSS. Because of other advantages in computing speed and predictive capability, n conclude that the proposed MBSN has a promising practical application for core power distribution monitoring program development.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.562-570
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• 1995

The recent ABB/CE(Asea Brown Boveri Combustion Engineering) type pressurized oater reactor-s have the on-line monitoring system, i.e., the COLSS(core operating limit supervisory system), to prevent the specified acceptable fuel design limits from being violated during normal operation and anticipated operational occurrences. One of the main functions of COLSS is the on-line monitoring of the DNB(departure from nucleate boiling) overpower margin by calculating the MDNBR(mini-mum DNB ratio) for the measured operating condition at every second. The CETOP-D model, used in the MDNBR calculation of COLSS, is benchmarked conservatively against the TORC mod-el using an inlet flow factor of hot assembly in CETOP-D as an adjustment factor for TORC. In this study, a technique to optimize the CETOP-D inlet flow factor has been developed by elim-inating the excessive conservatism in the ABB/CE's. A correlation is introduced to account for the actual variation of the CETOP-D inlet flow factor within the core operating limits. This technique was applied to the core operating range of the YongGwang Units 3&4 Cycle 1, which results in the increase of 2％ in the DNB overpower margin at the normal operating condition, compared with that from the ABB/CE method.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.251-256
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• 1997

The safety and reliablity of nuclear power plant operations relies heavily on the plant operators ability to respond to various emergency situations. It has become standard industry practice to utilize simulators to improve the safety and reliability of nuclear power plants operations. The simulators built for Younggwang#3("YGN#3"), which is based on the Korean Standard Nuclear Power Plant ("KSNPP")design, has been developed precisely for this purpose. The YGN#3 simulator is the first simulator in Korea to be developed locally and is now operational on site. A particular attention was placed on the development of CPC/COLLS safety system which is unique to the YGN#3. The effort to develop CPC/COLLS simulation model has been successful and plans exist for applying this model to simulator projects in the future.jects in the future.