A Statistical Model for Accessing Wall Thinning Rate due to Flow Accelerated Corrosion Based on Inspection Data in Nuclear Power Plants

2014 ◽  
Author(s):  
Yuyun Zeng ◽  
Jingquan Liu ◽  
Weilin Huang
Keyword(s):  
Statistical Model ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Lifetime Distributions ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Inspection Data ◽  
Flow Accelerated Corrosion ◽  
Thinning Rate

Flow accelerated corrosion (FAC) is a major degradation form of carbon steel and low alloy pipes in the secondary circuit of pressurized water reactor (PWR) plants, which has great impact on plant safety and reliability. For the purpose of effectively monitoring FAC in nuclear power plants, a statistical model for accessing FAC wall thinning rate using plant inspection data is proposed in this paper. The presented model is developed based on Gaussian stochastic process models. Wall thinning rate is considered as a function of key factors that have important influence on the FAC process (i.e., temperature, pH, mass transfer coefficient, etc.). The Kriging method, which has been widely applied in the domain of spatial analysis, is used to model the relationship between wall thinning rate and its impact factors. Model parameters are determined through maximum likelihood estimation using the inspection data. Since the likelihood function of the Kriging model is usually complicated in form, the genetic algorithm is employed to find parameter values that maximize this function. From the presented model, residual lifetime distributions of pipes affected by FAC can be derived, and conditions that may lead to high FAC rate can be found, which provides decision-making support for maintenance strategies optimization in life cycle management of the feed water system. Wall thinning data simulated from a physical-chemical mechanism model presented in literature are used to verify the presented model. Results of validation show that reasonable wall thinning rates and lifetime distributions can be obtained using this model.

Effects of Flow Accelerated Corrosion on Piping Steady-State Vibration Evaluations

2003 ◽  
Author(s):  
Brian J. Voll
Keyword(s):  
Steady State ◽  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
Vibration Monitoring ◽  
Accelerated Corrosion ◽  
Monitoring Programs ◽  
Wall Thinning ◽  
Piping Systems ◽  
Flow Accelerated Corrosion

Piping steady-state vibration monitoring programs were implemented during preoperational testing and initial plant startup at most nuclear power plants. Evaluations of piping steady-state vibrations are also performed as piping and component failures attributable to excessive vibration are detected or other potential vibration problems are detected during plant operation. Additionally, as a result of increased flow rates in some piping systems due to extended power uprate (EPU) programs at several plants, new piping steady-state vibration monitoring programs are in various stages of implementation. As plants have aged, pipe wall thinning resulting from flow accelerated corrosion (FAC) has become a recognized industry problem and programs have been established to detect, evaluate and monitor pipe wall thinning. Typically, the piping vibration monitoring and FAC programs have existed separately without interaction. Thus, the potential impact of wall thinning due to FAC on piping vibration evaluations may not be recognized. The potential effects of wall thinning due to FAC on piping vibration evaluations are reviewed. Piping susceptible to FAC and piping susceptible to significant steady-state vibrations, based on industry experience, are identified and compared. Possible methods for establishing links between the FAC and vibration monitoring programs and for accounting for the effects of FAC on both historical and future piping vibration evaluations are discussed.

A Procedure for Determining the Safe Operation Time of Equipment and Pipelines Based on Nondestructive Testing Results

Vestnik MEI ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 11-17
Author(s):  
Dmitriy A. Kuz'min ◽  
◽  
Aleksandr Yu. Kuz'michevskiy ◽  
Artem E. Gusarov ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
Wall Thickness ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Operation Time ◽  
Safe Operation ◽  
Accelerated Corrosion ◽  
Equipment And Pipelines ◽  
Flow Accelerated Corrosion

The reliability of nuclear power plants (NPPs) has an influence on power generation safety and stability. The reliability of NPP equipment and pipelines (E&P), and the frequency of in-service inspections are directly linked with damage mechanisms and their development rates. Flow accelerated corrosion (FAC) is one of significant factors causing damages to E&P because these components experience the influence of high pressure, temperature, and high flow velocity of the inner medium. The majority of feed and steam path components made of pearlitic steels are prone to this kind of wear. The tube elements used in the coils of high pressure heaters (HPH) operating in the secondary coolant circuit of nuclear power plants equipped with a VVER-1000 reactor plant were taken as the subject of the study. The time dependences of changes in the wall thickness in HPH tube elements are studied proceeding from an analysis of statistical data of in-service nondestructive tests. A method for determining the initial state of the E&P metal wall thickness before the commencement of operation is proposed. The article presents a procedure for predicting the distribution of examined objects' wall thicknesses at different times of operation with determining the occurrence probability of damages caused by flow accelerated corrosion to calculate the time of safe operation until reaching a critical state. A function that determines the boundary of permissible values of the HPH wall thickness distributions is obtained, and it is shown that the intervals of in-service inspections can be increased from 6 years (the actual frequency of inspections) to 9 years, and the next in-service inspection is recommended to be carried out after 7.5 years of operation. A method for determining the existence of FAC-induced local thinning in the examined object has been developed. The developed approaches and obtained study results can be adapted for any pipelines prone to wall thinning to determine the frequency of in-service inspections (including an express analysis based on the results of a single nondestructive in-service test), the safe operation time, and quantitative assessment of the critical value reaching probability.

Flow Accelerated Corrosion Program in the Belgian Nuclear Power Plants

2009 ◽  
Author(s):  
Anne-Sophie Bogaert ◽  
Michel Desmet ◽  
Arnaud Gendebien
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Ultrasonic Inspection ◽  
Accelerated Corrosion ◽  
Balance Of Plant ◽  
Nuclear Plants ◽  
Set Up ◽  
Predictive Software ◽  
Flow Accelerated Corrosion

Since the Surry-accident of 1986, Electrabel and Tractebel Engineering have performed extensive ultrasonic inspection campaigns to detect pipe wall thinning due to Flow Accelerated Corrosion (FAC) in the Balance-of-Plant systems of the seven Belgian nuclear power plants. Since 2000 EPRI’s predictive software CHECWORKS is used as a means to focus future inspections on the most susceptible components. In 2005, Tractebel Engineering participated in a benchmark set-up by the Framatome Owners Group (FROG) that compared the different FAC predictive models used by the FROG members. In 2006, Electrabel and Tractebel Engineering decided to perform an assessment of the way in which the follow-up of Flow Accelerated Corrosion (FAC) is done in the Belgian nuclear plants. This paper summarizes the Flow Accelerated Corrosion program in the Belgian nuclear plants as well as some of the main aspects of the Flow Accelerated Corrosion management, including the use of a predictive software, the method of inspections and the actions taken to keep the FAC program up to date.

Wall Thinning Analyses for Secondary Side Piping of Korean NPPS Using CHECWORKS Code

2002 ◽  
Author(s):  
K. M. Hwang ◽  
T. E. Jin ◽  
S. H. Lee ◽  
S. C. Jeon
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Operating Time ◽  
Accelerated Corrosion ◽  
Wear Rates ◽  
Wall Thinning ◽  
Management Technology ◽  
Reactor Types ◽  
Secondary Side

Since the mid-1990s, nuclear power plants in Korea have experienced wall thinning, leaks, and ruptures of secondary side piping caused by flow-accelerated corrosion (FAC). The pipe failures have increased as operating time progresses. In order to prevent FAC-induced pipe failures and to develop an effective FAC management strategy, KEPRI and KOPEC, along with KHNP’s support, have conducted a study for developing a systematic FAC management technology for all domestic nuclear power plants. As part of the study, FAC analyses were performed using CHECWORKS code. The analysis results were used to select components for inspection on each nuclear power plant. The site application feasibility of the analysis results was proven by comparisons of predicted and measured wear rates. This paper focuses on the introduction of the FAC analysis results for secondary side piping associated with three types of domestic nuclear power plants and the comparisons of predicted and measured wear rates. This paper also represents the comparisons of analysis results according to reactor types, power rates, and systems to facilitate the development of FAC management technology.

Wall-Thinning Analysis of the Pipelines in the Secondary Section of NPP

2013 ◽  
Author(s):  
Na Ma ◽  
Li Wang ◽  
Jinguang Qin
Keyword(s):  
Carbon Steel ◽  
Nuclear Power ◽  
Power Plants ◽  
Xrd Analysis ◽  
Operating Conditions ◽  
Chemical Compositions ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Erosion Corrosion ◽  
Flow Accelerated Corrosion

Wall-thinning investigation of three carbon steel pipe samples from secondary section of nuclear power plants has been carried out in this paper. The operating conditions of the three pipe samples are quite different, which leads to the different wall-thinning reasons and characteristics of the pipes. The chemical compositions of the steel materials, the stereomicroscope examinations, SEM examinations, as well as the XRD analysis are performed. The results show that: The wall-thinning of No.1 elbow was caused by erosion corrosion; the wall-thinning of No.2 elbow was caused by flow accelerated corrosion; the wall-thinning and crevasse of No.3 orifice plate was caused by cavitations. Measures to solve the wall-thinning problems of different pipes are also given in this paper.

Development of an On-Line Ultrasonic System to Monitor Flow-Accelerated Corrosion of Piping in Nuclear Power Plants

2004 ◽  
Vol 270-273 ◽  
pp. 2232-2238 ◽  
Author(s):  
Na Young Lee ◽  
Chi Bum Bahn ◽  
Sang Geun Lee ◽  
Ji Hyun Kim ◽  
Il Soon Hwang ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Accelerated Corrosion ◽  
On Line ◽  
Flow Accelerated Corrosion

Erosion in Nuclear Piping Systems

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Harold M. Crockett ◽  
Jeffrey S. Horowitz
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Cavitation Erosion ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Droplet Impingement ◽  
Accelerated Corrosion ◽  
Piping Systems ◽  
Flow Accelerated Corrosion

Various mechanisms degrade components and power piping in nuclear power plants. The mechanism with the greatest consequence has been flow-accelerated corrosion (FAC). FAC has caused ruptures and leaks and has led to numerous piping replacements. United States utilities use a combination of EPRI guidance, software, and aggressive inspection programs to deal with FAC. However, current technology does not detail guidance for erosive forms of attack including, cavitation erosion, flashing erosion, droplet impingement, and solid particle erosion. These forms of degradation have caused shutdowns, and leaks have become a maintenance issue. This brief will present a description of erosive damage mechanisms found in nuclear power plants.

Sign in / Sign up

Export Citation Format

Share Document