• Corrosion Science and Technology
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• 제12권2호
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• pp.79-84
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• 2013

In general, pipelines at nuclear power plants are affected by various types of degradation mechanisms and may be ruptured after gradually thinning. FAC (Flow-Accelerated Corrosion) is typical aging mechanism affecting the secondary side piping system. In Korea nuclear power plants, CHECWORKS program have been used for management of wall thinning damages. However, sometimes, CHECWORKS program shows wrong results at the stage of NFA (Network Flow Analysis) in case of complex pipelines. This paper describes the calculation results of pressure drop in a complex pipeline and single line by using the CHECWORKS program and the analysis results are compared with those of engineering calculation results including errors between them.

• 대한기계학회논문집B
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• 제34권4호
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• pp.437-442
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• 2010

고온, 고압의 유체가 흐르는 탄소강 배관에서는 유동가속부식으로 인한 배관감육 현상이 발생할 수 있다. 화력 및 원자력발전소에서 유동가속부식으로 인한 배관 손상시 고비용의 보수와 발전 정지를 유발할 뿐 아니라 발전소 신뢰도 및 안전성에 영향을 미칠 수도 있다. CHECWORKS 프로그램은 국내 발전소에서 유동가속부식에 의한 배관 손상을 예방하기 위하여 배관 두께검사 데이터를 평가하고 검사 계획을 수립하는데 이용되어 왔다. 그러나 상기 프로그램은 원전 2차측 배관 모두를 데이터베이스화한 후에 배관라인 그룹별로 유동가속부식 손상을 예측하기 때문에 국부적으로 감육에 민감한 부위를 찾는데 어려움이 있다. 본 논문에서는 CHECWORKS 프로그램을 이용하여 해석을 수행하고 수치해석을 통하여 검증할 수 있는 방법론을 기술하였다. 또한 국내 원전 2개의 배관 라인그룹에 대하여 CHECWORKS 프로그램을 이용한 유동가속부식 민감 부위를 FLUENT를 이용한 수치해석 결과와 비교하였다.

• 대한기계학회논문집B
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• 제34권4호
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• pp.429-435
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• 2010

국내를 포함한 전 세계 50여개 원전의 발전사업자는 유동가속부식에 의한 탄소강 배관 감육을 관리하기 위하여 CHECWORKS 프로그램을 이용하고 있다. CHECWORKS 프로그램은 대구경 배관에만 적용 가능한 것으로 알려져 있기 때문에 소구경 배관에 대해서는 현장 배관감육 관리 담당자의 경험과 판단에 따라 배관을 관리하고 있다. 이에 따라 본 논문에서는 국내 원전 소구경 배관 4개 라인그룹에 대하여 CHECWORKS 프로그램과 FLUENT 코드를 이용하여 유동가속부식과 유동 특성을 분석하였다. 그 결과 현장 배관감육 관리 담당자의 기술력에 따라 CHEC- WORKS 프로그램도 소구경 배관 감육 관리에 이용할 수 있는 것으로 나타났다.

• Corrosion Science and Technology
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• 제17권6호
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• pp.317-323
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• 2018

Assumptions have always been that wall thinning on the secondary side piping in nuclear power plants is mostly caused by Flow-Accelerated Corrosion (FAC). Recent studies have showed that wall thinning on the secondary side piping is caused by Liquid Droplet Impingement Erosion (LDIE), Solid Particle Erosion (SPE), cavitation, and flashing. To manage those aging mechanisms, several software such as CHECWORKS, COMSY, and BRT-CICERO have been used in nuclear power plants. Korean nuclear power plants have been using the CHECWORKS program since 1996 to date. However, many site engineers have experienced a lot of inconveniences and problems in using the CHECWORKS program. In order to work through the inconveniences and to remedy problems, KEPCO-E&C has developed a "3D-based pipe wall thinning management program (ToSPACE)" based on the experience of over 30 years in relation to the pipe wall thinning management. This study compares the results of FAC and LDIE analysis using both the CHECWORKS and ToSPACE programs with respect to validation of the wall thinning analysis results.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 춘계학술발표회요약집
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• pp.127.2-127
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• 2001

• Nuclear Engineering and Technology
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• 제31권4호
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• pp.375-384
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• 1999

The credibility of CHECWORKS FAC model analysis was evaluated for plant application in a model plant chosen for demonstration. The operation condition at each pipe component was defined before the wear rate analysis by plant data base, water chemistry analysis, and network flow analysis. The predicted wear was compared with the measured wear for 57 sample components selected from 43 susceptible line groups analysed. The inspected 57 locations represent components of highest predicted wear in each line group. Both absolute value and relative ranking comparisons indicated reasonable correlations between the predicted and the measured values. Four components showed much higher measured wear rates than the predicted ones in the feed water train from main feed water pump discharge to steam generator, probably due to high hydrazine concentration operation the effect of which had not been incorporated into the CHECWORKS model. The measured wear was higher than the predicted one consistently for components with least susceptibility to FAC. It is believed that the conservatism maintained during UT data analysis dominated the measurement accuracy. A great deal of enhancement is anticipated over the current plant pipe management program when a comprehensive plant pipe management program is implemented based on the model analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.807-812
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• 2001

This paper represents the wall thinning analysis results for secondary side piping of two types of domestic nuclear power plants based on the DB establishment and F AC analysis study for NPP secondary system piping. CHECWORKS code utilized in this study has been applied world widely to wall thinning analyses for secondary side piping and its reliability has also been proved. The predicted wear rates for several piping systems of a pressurized water reactor NPP are compared with those of a pressurized heavy water reactor NPP and with the measured wear rates. On the basis of comparison results of the predicted and measured wear rates, the analysis results can be effectively applied to the development of a standard thinned pipe management program targeted all domestic nuclear power plants.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.616-621
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• 2001

Flow-accelerated corrosion(FAC) is a phenomenon that results in metal loss from piping, vessels, and equipment made of carbon steel. FAC occurs only under certain conditions of flow, chemistry, geometry, and material. Unfortunately, those conditions are in much of the high-energy piping in nuclear and fossil-fueled power plants. Also, for domestic NPP secondary pipings whose operating time become longer, more evidences of FAC have been reported. The authors are studying on FAC management using CHECWORKS, computer code developed by EPRI. This paper is on the prediction results of metal loss by FAC in the one of CANDU type NPP secondary piping systems.

• Corrosion Science and Technology
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• 제15권1호
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• pp.6-12
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• 2016

Flow-Accelerated Corrosion (FAC) is a well-known degradation mechanism that attacks the secondary piping in nuclear power plants. Since the Surry Unit 2 event in 1986, most nuclear power plants have implemented management programs to deal with damages in carbon and low-alloy steel piping. Despite the utmost efforts, damage induced by FAC still occurs in power plants around the world. In order to predict FAC wear, some computer programs were developed such as CHECWORKS, CICERO, and COMSY. Various data need to be input to these programs; the chemical composition of secondary piping, flow operating conditions and piping geometries. CHECWORKS, developed by the Electric Power Research Institute (EPRI), uses a geometry code to calculate geometry effects. Such a relatively simple geometry code is limited in acquiring the accuracy of FAC prediction. Recently, EPRI revisited the geometry code with the intention of updating it. In this study, numerical simulations were performed for two adjacent $90^{\circ}$ elbows and the results were analysed in terms of the proximity effect between the two adjacent elbows.

• Corrosion Science and Technology
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• 제11권3호
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• pp.89-95
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• 2012

U.S. Electric Power Research Institute (EPRI) has developed CHECWORKS program and applied it to power plant piping lines since some lines were ruptured by flow-accelerated corrosion (FAC) in 1978. Nowadays the CHECWORKS program has been used to manage pipe wall thinning phenomena caused by FAC. However, various erosion mechanisms can occur in carbon-steel piping. Most common forms of erosion are cavitation, flashing, liquid droplet impingement erosion (LDIE), and Solid Particle Erosion (SPE). Those erosion mechanisms cause pipe wall thinning, leaking, rupturing, and even result in unplanned shutdowns of utilities. Especially, in two phase condition, LDIE damages a wide scope of plant pipelines. Furthermore, LDIE is the major culprit to cause such as power runback by pipe leaking. This paper describes the methodologies that manage wall thinning and also predict LDIE wall thinning area. For this study, current properties of two-phase condition are investigated and LDIE areas are selected. The areas are checked by B-Scan method to detect the effect of wall thinning phenomena.