Solving the problems of erosion-corrosion wear of equipment and pipelines in nuclear power plants: Domestic and international experience

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.

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SOME ASPECTS OF NON-DESTRUCTIVE TESTING OF EQUIPMENT AND PIPELINES OF NUCLEAR POWER PLANTS

Kontrol Diagnostika ◽

10.14489/td.2021.04.pp.020-026 ◽

2021 ◽

pp. 20-26

Author(s):

V. M. Ushakov

Keyword(s):

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Non Destructive Testing ◽

Destructive Testing ◽

Energy Agency ◽

Safety Standards ◽

Equipment And Pipelines ◽

Non Destructive

Topical aspects of non-destructive testing (NDT) of equipment and pipelines of power units of nuclear power plants (NPP) are considered. Non-destructive testing is an integral part of the entire life cycle of a nuclear power plant. Briefly analyzed documentation and types of non-destructive testing at the stage of manufacturing equipment and pipelines. Power of ultrasonic testing of welded joints of pipelines with a thickness of 2 to 6 mm. The main points of drawing up technological maps of non-destructive testing are noted. A brief analysis of the application of non-destructive testing in accordance with the requirements of the regulatory documents of the Russian Federation and the safety standards of the International Atomic Energy Agency is provided. It is shown that in recent years there has been a tendency to expand the role of NDTs from the classical approach of detecting and assessing defects to the use of NDTs in the study of metal degradation and ageing processes during the operation of NPP equipment and pipelines.

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THE NON-DESTRUCTIVE TESTING FOR AGING MANAGEMENT OF EQUIPMENT AND PIPELINES AT NUCLEAR POWER PLANTS. REVIEW

Kontrol Diagnostika ◽

10.14489/td.2020.05.pp.006-018 ◽

2020 ◽

pp. 6-18

Author(s):

V. M. Ushakov ◽

S. G. Evtushenko ◽

A. D. Zhukov ◽

A. S. Yurechko

Keyword(s):

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Noise Analysis ◽

Efficient Solutions ◽

Non Destructive Testing ◽

Destructive Testing ◽

Degradation Factor ◽

Equipment And Pipelines ◽

Non Destructive

The paper presents some approaches and methods for assessing and evaluation of different properties of equipment and pipelines metal of nuclear power plants during an operation such as a stress-strain state, a temperature and electrochemical effects. A problem statement for ageing management is considered for such metal properties of the heat – bearing agents. For this purpose, an observation of literature is provided for non – destructive testing (NDT) methods that have a correlation to a degradation factor defined by certain properties. There is has been made a case to apply NDT methods as a promising tool for an estimation and evaluation of degradation factor for a metal of potentially hazardous equipment. For this purpose there are proposed some rational and efficient solutions likes of acoustic methods based on structural – reverberation noise analysis, electromagnetic methods based on a coercive field strength deviation and electrical methods based on principles of potentiometry.

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Improvement and optimization of techniques for monitoring erosion-corrosion wear of equipment and pipelines at nuclear power stations

Thermal Engineering ◽

10.1134/s0040601509020086 ◽

2009 ◽

Vol 56 (2) ◽

pp. 134-141 ◽

Cited By ~ 4

Author(s):

V. N. Lovchev ◽

D. F. Gutsev ◽

G. V. Tomarov ◽

A. A. Shipkov

Keyword(s):

Nuclear Power ◽

Corrosion Wear ◽

Power Stations ◽

Erosion Corrosion ◽

Equipment And Pipelines

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Vulnerability Analysis of Pipelines and Equipment of the Existing NPP Power Units with VVER-1000 under Vibrations Caused by the Aircraft Crash

Nuclear and Radiation Safety ◽

10.32918/nrs.2017.1(73).08 ◽

2017 ◽

Author(s):

L. Shamis ◽

T. Matchenko ◽

T. Veriuzhska

Keyword(s):

Risk Assessment ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Nuclear Reactor ◽

Low Frequency ◽

Failure Risk ◽

Equipment And Pipelines ◽

Ultimate Resistance ◽

Aircraft Crash

Low-frequency dynamic loads from earthquakes were taken into account in the design of the equipment and pipelines of the existing nuclear power plants. Therefore, in the case of an aircraft crash impact on a nuclear reactor containment, exciting intense high-frequency vibrations of the building, the reliability of the nuclear power plant cannot be guaranteed without the failure risk assessment of objects that are involved in the safe shutdown. The paper suggests a method of the failure risk assessment using the concept of the ultimate resistance of pipelines and equipment of nuclear power plants to vibrations typical for the “aircraft crash” emergency design situation. The ultimate resistance is defined by the value of the load impulse, the application of which results in the probability of failure of the considered pipeline or equipment of 0.01 taking into account that it performs functions to provide 0.50 safety.

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