Nuclear Power Plants In Korea Research Articles

A SENSITIVITY ANALYSIS OF THE KEY PARAMETERS FOR THE PREDICTION OF THE PRESTRESS FORCE ON BONDED TENDONS

Bonded tendons have been used in reactor buildings at some operating nuclear power plants in Korea. Assessing prestress force on these bonded tendons has become an important pending problem in efforts to assure continued operation beyond their design life. The System Identification (SI) technique was thus developed to improve upon the existing indirect assessment technique for bonded tendons. As a first step, this study analyzed the sensitivity of the key parameters to prestress force, and then determined the optimal parameters for the SI technique. A total of six scaled post-tensioned concrete beams with bonded tendons were manufactured. In order to investigate the correlation of the natural frequency and the displacement to prestress force, an impact test, a Single Input Multiple Output (SIMO) sine sweep test, and a bending test using an optical fiber sensor and compact displacement transducer were carried out. These tests found that both the natural frequency and the displacement show a good correlation with prestress force and that both parameters are available for the SI technique to predict prestress force. However, displacements by the optical fiber sensor and compact displacement transducer were shown to be more sensitive than the natural frequency to prestress force. Such displacements are more useful than the natural frequency as an input parameter for the SI technique.

An integrated translation of design data of a nuclear power plant from a specification-driven plant design system to neutral model data

Abstract How to efficiently integrate and manage lifecycle data of a nuclear power plant has gradually become an important object of study. Because plants usually have a very long period of operation and maintenance, the plant design data need to be presented in a computer-interpretable form and to be independent of any commercial systems. The conversion of plant design data from various design systems into neutral model data is therefore an important technology for the effective operation and maintenance of plants. In this study, a neutral model for the efficient integration of plant design data is chosen from among the currently available options and extended in order to cover the information model requirements of nuclear power plants in Korea. After the mapping of the neutral model and the data model of a specification-driven plant design system, a plant data translator is also implemented in accordance with the schema mapping results.

Reliability of Covariates in Baseline Survey of a Cohort Study: Epidemiological Investigation on Cancer Risk Among Residents Who Reside Near the Nuclear Power Plants in Korea

We evaluated the reliability of the possible covariates of the baseline survey data collected for the Epidemiological Investigation on Cancer Risk Among Residents Who Reside Near the Nuclear Power Plants in Korea. Follow-up surveys were conducted for 477 participants of the cohort at less than 1 year after the initial survey. The mean interval between the initial and follow-up surveys was 282.5 days. Possible covariates were identified by analyzing the correlations with the exposure variable and associations with the outcome variables for all the variables. Logistic regression analysis with stepwise selection was further conducted among the possible covariates to select variables that have covariance with other variables. We considered that these variables can be representing other variables. Seven variables for the males and 3 variables for the females, which had covariance with other possible covariates, were selected as representative variables. The Kappa index of each variable was calculated. For the males, the Kappa indexes were as follow; family history of cancer was 0.64, family history of liver diseases in parents and siblings was 0.56, family history of hypertension in parents and siblings was 0.51, family history of liver diseases was 0.50, family history of hypertension was 0.44, a history of chronic liver diseases was 0.53 and history of pulmonary tuberculosis was 0.36. For females, the Kappa indexes were as follow; family history of cancer was 0.58, family history of hypertension in parents and siblings was 0.56 and family history of hypertension was 0.47. Most of the possible covariates showed good to moderate agreement.

Application and experience of a two-dosimeter algorithm for better estimation of effective dose during maintenance periods at Korea nuclear power plants

The application of a two-dosimeter and its algorithm and a test of its use in an inhomogeneous high radiation field are described. The goal was to develop an improved method for estimating the effective dose during maintenance periods at Korean nuclear power plants (NPPs). The application and experience to KNPPs was evaluated using data for each algorithm from two-dosimeter results for an inhomogeneous high radiation field during maintenance periods at Korean NPPs.

Korea's progress on the ITER tritium systems

Korea has been operating four units of CANDU nuclear power plant since 1983. Tritium generated in the heavy water of the plant has been removed by Wolsong TRF (tritium removal facility) since 2007. Korea has developed a 500-kCi BU-type tritium transport container. Furthermore, strictly controlled tritium release to the environment from the CANDU nuclear power plant in Korea will also be a helpful experience for ITER. The BU-type tritium transport container will be unpacked and the quantity of tritium in the metal tritides of the primary vessel will be measured accurately before the tritium is liberated by heating the metal tritides. In the ITER fuel cycle plant, Korea is responsible for the development and supply of the SDS (fuel storage and delivery system). We present the on-going R&D progress to use a non-nuclear material ZrCo for the storage and delivery of tritium. Especially we present the delivery characteristics of the ZrCo hydride bed by considering the fueling requirement and maintainability of the ZrCo hydride bed. We also present various test results for the experimental ZrCo beds and the test programs for the leak tight large scroll pump with a magnetic coupling-drive.

Development of Speed Controller and its Application to a 680[MW] Rated Steam Turbine

An analog type turbine control system in a nuclear power plant in Korea was replaced by a digital type control system successfully. The turbine simulator was used to verify and validate the perfection of newly developed digital control system prior to its actual installation. In this paper, the newly developed turbine speed control system, ie. governor will be introduced together with how to simulate entire control loop. After that, we will compare the comparison of simulation result in laboratory with pre startup simulation result. Eventually the performance of actual operation result was testifed.

VISUAL MEASUREMENT METHOD USING A CIRCULAR GROOVE IMAGE FOR MEASURING INTERNAL DEFECTS OF PIPES IN NUCLEAR POWER PLANT

During the overhaul period of nuclear power plants in Korea, an ROV(Remotely Operated Vehicle) enters the cold-leg pipes connected with the reactor to examine the state of the thermal sleeves and their positions in the safety injection nozzles. To measure the positions of the thermal sleeves or scratches with video images recorded during the examination, time-varying camera parameters should be known, such as the focal length and principal points used for the capturing each video image. In this paper, we propose a camera calibration and measurement scheme by using a single image containing two circular grooves of a cylindrical nozzle whose radius and distance are known.

RETRACTED: Degradation of alloy 600 material component in a nuclear power plant in Korea

This article has been retracted at the request of the Author. Please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). Reason: This article has been retracted due to concerns in the release of proprietary information.

Neutron and Gamma Shielding Estimation for the KN-12 Cask

The comparison between calculated and measured dose rates of the cask for 12 spent fuels has been performed and this result confirms the shielding integrity of KN-12 transport cask to transport the spent fuel with safe. In February 2007, the dose rate measurements of KN-12 cask were performed in the spent fuel decontamination pit at the KORI Nuclear Power Plant in Korea. The general specifications of spent fuels being loaded into the cask were a burnup of around 33 GWD/MTU, an initial enrichment of 3.4 wt% and cooling times ranging from 15.8 years to 17 years. The discrete measurements were performed at several points for acquiring axial and radial dose rate profiles along the cask’s surface. All calculated and measured values showed the far less than dose rate requirements of 2000 μSv/h. The C/E ratios for neutron cases were generally about 1.0~2.8 except for the trunnions regions at cask’s side. The C/E ratios in gamma ray cases were about 1.1~2.7 at cask’s side. By this program the shielding integrity test for preservice inspection of KN-12 cask was successfully completed.

Quantitative Analysis of Meteorological Conditions for a Comparative Risk Estimation of Nuclear Power Plants in Korea

The meteorological conditions of Korean nuclear power plant sites were analyzed by using the integral parameters developed by Allwine and Whiteman. The method of integral parameters was applied to 76 sites in Korea which are evenly distributed. The integral quantities of stagnation and recirculation were calculated at four nuclear power plant (NPP) sites and these values were analyzed with the distribution of the integral quantities estimated with the results of the 76 sites. The comparative study shows that the meteorological conditions of the four NPP sites in Korea are quite good from the meteorological aspects.

WITHDRAWN: Tube degradation of steam generator in nuclear power plants in Korea

This article has been withdrawn at the request of the Author. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy .

월성원자력발전소 온배수가 해조류 종조성 및 군집구조에 미치는 영향

Marine algal flora and community structure were seasonally examined at three sites in the vicinity of the Wolseong nuclear power plant in Korea from February to November 2006. A total of 126 seaweeds including 25 green, 31 brown, 70 red algae, and 1 marine plant were identified. The greatest number ...

The Intakes and Committed Effective Dose from Internally Deposited Iodine-131 due to an Internal Contamination Event of Ulchin Nuclear Power Plant in Korea–Experiences and Lessons Learnt

This paper describes the lessons learned after 131I(iodine-131) contamination at Korean nuclear power plnats during the refueling period, including whole body counting measurement systems, the estimation of intake, and the calculation of committed effective dose. In particular, various internal dose calculations and computer programs were applied with the revised biokinetic models and a new dosimetric model for the human respiratory tract of ICRP. Finally, the estimated intake and committed effective dose were reviewed and intercompared based on the intake retention fraction of the ICRP.

Near-surface geophysical studies in the Ulsan Fault Zone of Korea

Recent earthquakes near nuclear power plants in Korea have triggered public concerns about possible seismicity of the Ulsan Fault Zone in the south-eastern part of the Korean peninsula. To reveal subsurface structures of this fault zone, we conducted high-resolution seismic refraction and reflection surveys, and closely spaced gravity measurements in the Dongchon River valley north of Ulsan, Korea. Here alluvium covers the north–south trending fault zone in a 1-km wide valley. Both source points and receivers were spaced at 5-m intervals for the 24-channel seismic refraction and reflection methods, along two profiles of 835 m and 415 m length. Gravity data were also measured along these profiles at 131 stations using a 10-m interval. Synergetic interpretation of seismic refraction, high-resolution seismic reflection, and gravity surveys across the valley indicates that the Ulsan Fault Zone was formed by apparent north–south strike-slip motions during the Cretaceous, and that some faults may have been reactivated by east–west compressional or transpressional stresses during the Tertiary or Quaternary.

Hydrazine-Dependency of Low-Alloy Steel Flow-Accelerated Corrosion in a Deoxygenated Solution at 250°C

In the nuclear power plants (NPPs), wall thinning of the piping materials is generally caused by a flow-accelerated corrosion (FAC) and leads to a rupture with no warning unless it is detected and repaired in a timely manner. To reduce the FAC, it is better to use low-alloy steels, such as 1Cr-½Mo and 2¼Cr-1Mo, having higher FAC-resistance than carbon steel. Meanwhile, in the secondary water chemistry at the NPPs in Korea, hydrazine concentration is maintained within the range of 100~150 ppb. For applying these low-alloys to a piping material, we investigated the influence of hydrazine concentration on their FAC. An experiment was carried out at pH25°C of 9 controlled with ammonia in a deoxygenated aqueous solution containing 0~250 ppb-hydrazine by using a FAC test loop at 250°C for 300 hours. Experimental weight loss showed a hydrazine concentration dependency of the FAC in this concentration range, giving minimum at 150 ppb.

Sharing product data of nuclear power plants across their lifecycles by utilizing a neutral model

Many public and private Korean organizations are involved during the lifecycle of a domestic nuclear power plant. Korea Plant Engineering Co. (KOPEC) participates in the design stage, Korea Hydraulic and Nuclear Power (KHNP) operates and manages all nuclear power plants in Korea, Doosan Heavy Industry and Construction Co. manufactures the main equipment, and a construction company constructs the plant. Even though each organization has its own digital data management system and obtains a certain level of automation, data sharing among organizations is poor. KHNP obtains drawings and technical specifications from KOPEC in the form of paper. This results in manual re-work of definitions, and errors can potentially occur in the process. In order to establish an information bridge between design and operation and maintenance (O&M) phases, a generic product model (GPM), a data model from Hitachi, is extended for constructing a neutral data warehouse and the Korean Nuclear Power Plant Information Sharing System (KNPISS) is implemented.

A study on the shell wall thinning causes identified through experiment, numerical analysis and ultrasonic test of high-pressure feedwater heater

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which accelerates as the operation progresses. Several nuclear power plants in Korea have undergone this damage around the impingement baffle – installed downstream of the high-pressure turbine extraction steam line – inside numbers 5A and 5B feedwater heaters. At that point, the extracted steam from the high-pressure turbine consists in the form of two-phase fluid at high temperature, high pressure and high velocity. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of number 5 high-pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes the comparisons between the numerical analysis results using the FLUENT code and the downscaled experimental data in an effort to determine root causes of the shell wall thinning of the high-pressure feedwater heaters. The numerical analysis and experimental data were also confirmed by the actual wall thickness measured by ultrasonic tests. From the comparison of the results for the local velocity profiles and the wall thinning measurements, the local velocity component only in the y-direction flowing vertically to the shell wall, and not in the x- and z-directions, was analogous to the wall thinning data.

Aging Management of Nuclear Power Plants in Korea

Kori Unit 1, which is the oldest nuclear power plant (NPP) in Korea has been operated since 1978. In addition, 10 other NPPs have been operating more than 10 years. As the number of aging plants rise, public concern over the safety of operating NPPs has increased. Periodic safety review (PSR) in addition to the existing safety assessments are proposed by IAEA as an effective way to verify that operating NPPs maintain the high level of safety. In this regard, the Ministry of Science and Technology (MOST), Korea’s nuclear regulatory body, recently established an institutional process through revision to the atomic energy act to introduce PSR. This PSR considers, among other factors, improvements in safety standards and practices, the cumulative effects of plant aging, operating experience, and the evolution of science and technology. In particular, the assessment and management of plant aging is one of the major areas. It includes identification of the system, structure and components (SSCs) for aging management, assessment of aging effects and planning of aging management implementation program. PSR results could be one of the procedural requirements that are utilized to renew an operating license of a NPP. This paper describes safety assessment requirements including PSR and aging management activities in Korea. This paper also includes the strategy and method for the application of PSR results to the aging management and continued operation of NPPs.

ICONE15-10201 PRESENT STATUS OF NUCLEAR CONTAINMENTS IN KOREA

Since the first nuclear power plant in Korea, Kori unit #1, was started in commercial service in 1978, 20 units including Kori unit #1 have been operated and maintained until now in Korea. Recently several units were started to be constructed and also, additionally more than 4 units were planned to be constructed in the near future. The importance of nuclear containments has been always one of the hottest issues for the safety and protection of nuclear power plants until now. At the beginning of nuclear power plants construction in Korea, several typed nuclear containment systems were adopted. For those reasons, various codes, standards, and inspection technologies are applied to nuclear containment systems differently. In this study, the status of inservice inspection performed for the safety and maintenance of nuclear containments in Korea was researched. Overall nuclear containment systems and inspections performed up to recently in Korea including trends, inspection items, periods, and regulations were described briefly.

급수가열기 추기노즐 충격판 주변의 동체감육 현상규명을 위한 실험 및 수치해석 연구

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle - installed downstream of the high pressure turbine extraction steam line - inside number 5A and 5B feedwater heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes the comparisons between the numerical analysis results using the FLUENT code and the down scale experimental data in an effort to determine root causes of the shell wall thinning of the high pressure feedwater heaters. The numerical analysis and experimental data were also confirmed by actual wall thickness measured by an ultrasonic test.