Review of Pipe Wall Thinning Mechanism Study and its National Project in Japan

2011 ◽  
Author(s):  
Hiroshi Miyano ◽  
Naoto Sekimura ◽  
Masayuki Takizawa ◽  
Masaaki Matsumoto
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
High Reliability ◽  
Safety Margin ◽  
Fiscal Year ◽  
Mechanism Study ◽  
Wall Thinning ◽  
Piping Systems ◽  
The Government

For nuclear power plants, the four major requirements are 1) high safety, 2) high reliability, 3) economical competitiveness, and 4) minimum environmental impact. However, it is still difficult to completely avoid problems concerning structural materials caused by stress corrosion cracking (SCC) and for piping systems caused by flow accelerated corrosion (FAC) and liquid drop impingement (LDI). Since especially FAC and LDI are uncertain phenomena as pipe wall thinning, there are the piping rupture accident risks on all piping systems under the specific conditions. In Japan, after August 2004, the accident of the secondary pipe rupture in Mihama Power Plant Unit 3, The Kansai Electric Power Co., Inc. (KEPCO), R&D projects on pipe wall thinning phenomena and mechanism have been employed by many organizations. On the other hand, evaluation of the safety and reliability of piping systems of long term operating plants and with the special attention to seismic condition have been requested. It was requested to enable evaluation of pipe wall thinning and its reliability with more accuracy. This project was programmed under the government budget from 2006 to 2010 fiscal year according to the Strategy Load-Map for Ageing Management generated by the society of industry, government and academia [1]. As the milestone for the first half decade of the load-map, the project had these achievements: 1) Establish computer program for FAC simulation, 2) Clarify droplet behavior for LDI prediction, 3) Simplified calculation model of pipe wall thinning for seismic evaluation, 4) Evaluate safety margin of thinned piping by FAC or LDI.

Review of Pipe Wall Thinning and Seismic Evaluation in Japan

2009 ◽  
Author(s):  
Hiroshi Miyano ◽  
Katsuji Maeda ◽  
Masayuki Takizawa ◽  
Naoto Sekimura
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
High Reliability ◽  
Fiscal Year ◽  
Accident Risk ◽  
Seismic Evaluation ◽  
Wall Thinning ◽  
Piping Systems ◽  
The Government

For nuclear power plants, the four major requirements are 1) high safety, 2) high reliability, 3) good economical acceptability, and 4) as few as possible environmental impact. However, it is still difficult to completely avoid problems for structural materials as structural stress corrosion cracking (SCC) and for piping systems as flow accelerated corrosion (FAC), liquid drop impulsion erosion (LDI). Especially FAC and LDI are uncertainty phenomenon as pipe wall thinning, so there is the piping rupture accident risk on all of piping systems under the specific conditions. In Japan, after in August 2004, the accident of the secondary pipe rupture in Mihama Power Plant Unit 3, The Kansai Electric Power Co., Inc. (KEPCO), R&D projects about pipe wall thinning phenomenon and mechanism had been promoted in many organizations. The other hand it is requested to evaluate the safety and reliability of piping systems of long term operating plant and with on special case of seismic condition. It was requested to be able to evaluate pipe wall thinning and its reliability with more accurate. This project had programmed under the government budget from 2006 planed until 2010 fiscal year [1]. At the mile stone of half span, the project had these fruits, 1) Computer program for FAC simulation, 2) Droplet phenomena for LDI simulation, 3) Simplified calculation model of pipe wall thinning for seismic evaluation.

Failure Probability Assessment of Piping Systems Affected by SCC and Pipe Wall Thinning for LBB Analysis

2011 ◽  
Author(s):  
Hiromasa Chitose ◽  
Hideo Machida ◽  
Itaru Saito
Keyword(s):  
Failure Probability ◽  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
Probability Assessment ◽  
Wall Thinning ◽  
Piping Systems ◽  
Leak Before Break ◽  
Thinning Rate ◽  
Service Inspection

This paper provides failure probability assessment results for piping systems affected by stress corrosion cracking (SCC) and pipe wall thinning in nuclear power plants. On the basis of the results, considerations for applying the leak-before-break (LBB) concept in actual plants are presented. The failure probability for SCC satisfies the target failure probability even if conservative conditions are assumed. Moreover, for pipe wall thinning analysis, pre-service inspection is important for satisfying the target failure probability because the initial wall thickness affects the accuracy of the wall thinning rate. The pipe wall thinning analysis revealed that the failure probability is higher than the target probability if the bending stress in the pipe is large.

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.

Load Factor for Evaluating Non-Planar Flaws in Carbon Steel Piping Using Limit Load Methodology

2016 ◽  
Author(s):  
Phuong H. Hoang
Keyword(s):  
Carbon Steel ◽  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
Local Strain ◽  
Limit Load ◽  
Evaluation Methodology ◽  
Load Factor ◽  
Wall Thinning ◽  
Steel Piping

Non-planar flaw such as local wall thinning flaw is a major piping degradation in nuclear power plants. Hundreds of piping components are inspected and evaluated for pipe wall loss due to flow accelerated corrosion and microbiological corrosion during a typical scheduled refueling outage. The evaluation is typically based on the original code rules for design and construction, and so often that uniformly thin pipe cross section is conservatively assumed. Code Case N-597-2 of ASME B&PV, Section XI Code provides a simplified methodology for local pipe wall thinning evaluation to meet the construction Code requirements for pressure and moment loading. However, it is desirable to develop a methodology for evaluating non-planar flaws that consistent with the Section XI flaw evaluation methodology for operating plants. From the results of recent studies and experimental data, it is reasonable to suggest that the Section XI, Appendix C net section collapse load approach can be used for non-planar flaws in carbon steel piping with an appropriate load multiplier factor. Local strain at non-planar flaws in carbon steel piping may reach a strain instability prior to net section collapse. As load increase, necking starting at onset strain instability leads to crack initiation, coalescence and fracture. Thus, by limiting local strain to material onset strain instability, a load multiplier factor can be developed for evaluating non-planar flaws in carbon steel piping using limit load methodology. In this paper, onset strain instability, which is material strain at the ultimate stress from available tensile test data, is correlated with the material minimum specified elongation for developing a load factor of non-planar flaws in various carbon steel piping subjected to multiaxial loading.

A Feasibility Study of Noncontact Ultrasonic Sensor for Nuclear Power Plant Inspection

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Akinori Tamura ◽  
Chenghuan Zhong ◽  
Anthony J. Croxford ◽  
Paul D. Wilcox
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
Thickness Measurement ◽  
Piping System ◽  
Wall Thinning ◽  
Plant Inspection ◽  
Ultrasonic Thickness

A pipe-wall thinning measurement is a key inspection to ensure the integrity of the piping system in nuclear power plants. To monitor the integrity of the piping system, a number of ultrasonic thickness measurements are manually performed during the outage of the nuclear power plant. Since most of the pipes are covered with an insulator, removing the insulator is necessary for the ultrasonic thickness measurement. Noncontact ultrasonic sensors enable ultrasonic thickness inspection without removing the insulator. This leads to reduction of the inspection time and reduced radiation exposure of the inspector. The inductively-coupled transducer system (ICTS) is a noncontact ultrasonic sensor system which uses electromagnetic induction between coils to drive an installed transducer. In this study, we investigated the applicability of an innovative ICTS developed at the University of Bristol to nuclear power plant inspection, particularly pipe-wall thinning inspection. The following experiments were performed using ICTS: thickness measurement performance, the effect of the coil separation, the effect of the insulator, the effect of different inspection materials, the radiation tolerance, and the measurement accuracy of wastage defects. These initial experimental results showed that the ICTS has the possibility to enable wall-thinning inspection in nuclear power plants without removing the insulator. Future work will address the issue of measuring wall-thinning in more complex pipework geometries and at elevated temperatures.

309 High Temperature Impact-Fretting Wear Experiments for Evaluation of Pipe Wall Thinning Phenomena in Nuclear Power Plants

2013 ◽  
Vol 2013.49 (0) ◽  
pp. 87-88
Author(s):  
Yoshiki SATO ◽  
Akira IWABUCHI ◽  
Michimasa UCHIDATE ◽  
Hitoshi YASHIRO ◽  
Akito OYAKAMA ◽  
...  
Keyword(s):  
High Temperature ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Pipe Wall ◽  
Fretting Wear ◽  
Wall Thinning ◽  
Temperature Impact

scholarly journals Development of ToSPACE for Pipe Wall Thinning Management in Nuclear Power Plants

2019 ◽  
Vol 09 (01) ◽  
pp. 1-15
Author(s):  
Kyeong Mo Hwang ◽  
Hun Yun ◽  
Hyeok Ki Seo ◽  
Geun Young Lee ◽  
Kyung Woo Kim
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Pipe Wall ◽  
Wall Thinning

scholarly journals A non-contact ultrasonic sensor for pipe-wall thinning inspection of nuclear power plants

2019 ◽  
Author(s):  
A. Tamura ◽  
M. Endo ◽  
N. Kono ◽  
H. Okazawa ◽  
S. Okido ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Pipe Wall ◽  
Ultrasonic Sensor ◽  
Wall Thinning

The Comprehensive Discussion of the Pipe Wall Thinning of Secondary System in BWR and PWR Nuclear Power Plants

2006 ◽  
Author(s):  
Taku Ohira ◽  
Tomohiko Hoshino
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Single Phase ◽  
Pipe Wall ◽  
Secondary System ◽  
Power Company ◽  
Wall Thinning ◽  
Secondary Systems ◽  
Pipe Bending

The behaviors of pipe wall thinning of secondary systems in The Japan Atomic Power Company (JAPC)’s BWR and PWR nuclear power plants were compared in this paper, to discuss the effects of respective factors contributing to corrosion protection of pipe. The rates of pipe wall thinning in single-phase flow environment, in both BWR and PWR, depend on temperature. Nevertheless, the rate of pipe wall thinning in PWR is more than that in BWR. The rates of pipe wall thinning at elbow of pipe, bending of pipe, straight run of pipe and reducer areas are mutually different, although they are located in the same line. Especially, the rates of pipe wall thinning at elbows of pipes, bendings of pipes, straight runs of pipes and reducers, which are located closely downstreams of the pumps discharge nozzles, elbows, orifices or bent pipes, depend on not the temperature but the pipe configuration.

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