D114 Verification of FAC mitigation effect by water chemistry improvement in PWR secondary system using continuous monitoring system of wall thickness of carbon steel piping

2013 ◽  
Vol 2013.18 (0) ◽  
pp. 111-114
Author(s):  
Wataru SUGINO ◽  
Takahiro ARAKAWA
Author(s):  
Z. H. Walker

In 1996, Flow Accelerated Corrosion (FAC) was identified as a degradation mechanism affecting carbon steel outlet feeder pipes in CANDU® (CANadian Deuterium Uranium) reactors. The maximum rate of FAC was estimated to be <0.120 mm/year. In response, wall thickness inspection programs have been implemented to identify and measure the minimum wall thickness in outlet feeder pipes. These data are necessary to ensure fitness-for-service of the feeder pipe. These data, together with the thermalhydraulic and geometric parameters for the measured feeders, are also very useful for developing empirical wall thickness models. Such models can be used to enhance the understanding of feeder wall thinning leading to an improved capability to predict future wall thickness minima and their locations. The determined dependency of the wall-thinning rate on thermalhydraulic conditions can be used to quantify the potential benefits of maintenance activities, such as steam generator cleaning. Activities such as steam generator cleaning are generally viewed as beneficial in recovering lost thermal efficiency, thereby reducing the severity of the thermalhydraulic conditions by reducing the amount of quality (steam phase) exiting the reactor core. Finally, when wall thickness models are applied to data from different plants, there is the potential of identifying operating conditions that can lead to lower rates of wall loss. This paper addresses the aforementioned important issues associated with FAC of ASME PVP Class 1 carbon steel piping.


1994 ◽  
Vol 153 (1) ◽  
pp. 57-69 ◽  
Author(s):  
Naoki Miura ◽  
Terutaka Fujioka ◽  
Koichi Kashima ◽  
Satoshi Kanno ◽  
Makoto Hayashi ◽  
...  

Author(s):  
Alexey Arzhaev ◽  
Sergey Butorin

Operating NPPs license extension activities in Russia produced strong demand for safety improvement of plants build according to earlier standards. Installation of additional supports as pipe whip restraints is one of requirement in acting regulatory documentation which should be followed or compensated by appropriate measures like Leak Before Break (LBB) analyses and improvement of In-Service Inspection (ISI) and Leak Detecting System (LDS). Basic document for LBB concept application to Russian NPP piping is RD 95 10547-99. Its requirements correspond to classical LBB principles used in many countries in Europe, USA and Japan. In many real cases requirements of RD 95 10547-99 could not be applied to safety important NPP piping systems due to the presence of specific features of operational degradation due to some corrosion mechanisms: for example, erosion-corrosion (E-C) for carbon steel piping and intergranular stress corrosion cracking (IGSSC) for heat affected zones of austenitic piping weldments. For special case of RBMK piping with outer diameter 325 mm (potentially susceptible to IGSCC) special Break Preclusion Concept has been developed in Russia after IAEA Extrabudgetary Program in 2000–2002. Contrary to LBB Concept demanding for all four basic principles to be completely fulfilled BP Concept accepts some principles to be fulfilled in a balanced way with demonstration of monitored degradation effectively achieved in operation. Special BP Concept is being developed now to support integrity assessment of RBMK carbon steel steam and feed water piping potentially susceptible to E-C which requires another set of measures to demonstrate principle of controlled degradation in operation then in case of austenitic steel piping. General scheme of piping integrity analyses according to LBB and BP Concepts is discussed and examples of specific approaches to achieve controlled degradation are illustrated in paper. As result of LBB and BP Concepts application it is possible to substantiate reject of additional piping whip restraints implementation on-site. Examples of similar safety methodology development in other countries have been reported at IAEA Specialists Meeting on LBB in Kiev, Ukraine in November 2006.


2021 ◽  
Author(s):  
Niels Pörtzgen ◽  
Ola Bachke Solem

Abstract During the construction of pipelines for the transportation of oil and gas, the inspection of girth welds is a critical step to ensure the integrity and thereby the safety and durability of the pipeline. In this paper we present an advanced technology ‘IWEX’ for the non-destructive testing of welds based on 2D and 3D ultrasonic imaging. This technology allows for safe, fast, and accurate inspection whereby the results are presented comprehensively. This will be illustrated with results from a recent project. The IWEX technology is based on an ultrasonic inspection concept, whereby ‘fingerprints’ of ultrasonic signals are recorded, also referred to as ‘full matrix capture’ (FMC) data. Then, an image area is defined, consisting out of pixels over an area large enough to cover the inspection volume. With the FMC data, image amplitudes are calculated for each pixel so that the shape of geometry (back wall, front wall, cap, and root) and possible indications are revealed. As opposed to traditional ultrasonic testing strategies, the detection and sizing of indications is therefore less dependent on its orientation. The project concerned the inspection of J and V welds from a 5.56″ diameter carbon steel pipe with an 8.4mm wall thickness. The wall thickness is relatively thin compared to common inspection scopes. Therefore, the inspection set-up was adapted, and procedural changes were proposed. Consequently, additional validation efforts were required to demonstrate compliance with the required inspection standard; DNVGL-ST-F101: 2017. As part of this, welds were scanned with seeded indications and the reported locations were marked for macro slicing under witnessing of an independent representative from DNVGL. The resulting images from the indications in the welds showed great detail with respect to the position, orientation and height of the indications. A quantitative comparison with the results from the macro slices was performed, including a statistical analysis of the height sizing and depth positioning accuracies. From the analysis, it could be observed that the expected improvements with respect to the resolution and sizing accuracy were indeed achieved. Thereby, the procedure has proven to be adequate for the inspection of carbon steel girth welds within the thin wall thickness range (~6mm to ~15mm). The IWEX technology is a member of the upcoming inspection strategy based on imaging of ultrasonic FMC data. This strategy can be considered as the next step in the evolution of inspection strategies after phased array inspection. The IWEX technology has been witnessed and qualified by independent 3rd parties like DNVGL, this makes the IWEX technology unique in its kind and it opens opportunities for further acceptance in the industry and other inspection applications.


Author(s):  
Phuong H. Hoang

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.


1995 ◽  
Vol 158 (2-3) ◽  
pp. 241-251 ◽  
Author(s):  
Y.J Kim ◽  
C.S Seok ◽  
Y.S Chang ◽  
J.O Kim ◽  
K.M Yang ◽  
...  

2001 ◽  
Author(s):  
John Donelson ◽  
Wayne M. Zavis ◽  
S. K. (John) Punwani ◽  
Monique Ferguson Stewart ◽  
Mark C. Edwards

Abstract Science Applications International Corporation (SAIC) and Wilcoxon Research have developed a real-time on-board condition monitoring system for freight trains. The Office of Research and Development of the Federal Railroad Administration funded the development of the system. The system monitors bearings, wheels, trucks and brakes on freight trains in order to detect equipment defects and derailments. The objectives of the system are to improve railroad safety and operation efficiency through continuous monitoring of mechanical components on freight trains.


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