Damage Evaluation and Life Extension of Structural Components

1986 ◽  
Vol 108 (3) ◽  
pp. 241-248 ◽  
Author(s):  
L. F. Coffin
Keyword(s):  
Structural Damage ◽  
Life Prediction ◽  
Nuclear Power ◽  
Power Plants ◽  
Past History ◽  
Life Extension ◽  
Remaining Life ◽  
Structural Components ◽  
Damage State ◽  
Critical Elements

This paper describes an approach to life prediction in which critical elements of major structural components are continuously monitored by appropriate damage indicators for structural damage, and, based on the indicated damage state, an on-line assessment is made of the remaining life. Concurrently alternative corrective measures can then be assessed and, if the life has been found wanting, appropriate actions taken. The process is viewed as a continuous one whereby the current remaining life of critical elements is known as the plant ages. The need for applying such procedures becomes increasingly important as some of our major structures approach their design life and concerns arise regarding retirement and replacement versus life extension. Important elements of this approach include definitions of damage, appropriate damage monitors, damage assessment, life prediction, and conseqeunces of corrective action. This paper treats these elements in the context of past history and current programs associated with pipe cracking in nuclear power plants.

Assessment of Remaining Life for Class 1 Piping Components Experiencing Wall Thinning

2004 ◽  
Author(s):  
Rajnish Kumar
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Life Extension ◽  
Remaining Life ◽  
Original Design ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Class 1 ◽  
Plant Components

Assessment of remaining life of power plant components is important in light of plant life management and life extension studies. This information helps in planning and minimizing plant outages for repairs and refurbishments. Such studies are specifically important for nuclear power plants. Nuclear Safety Solutions Limited (NSS) is involved in conducting such studies for plant operators and utilities. Thickness measurements of certain piping components carrying fluids at high temperature and high pressure have indicated higher than anticipated wall thinning rates. Flow accelerated corrosion (FAC) has been identified as the primary mechanism for this degradation. The effect of FAC was generally not accounted for in the original design of the plants. Carbon steel piping components such as elbows, tees and reducers are prone to FAC. In such cases, it is important to establish the remaining life of the components and assess their adequacy for continued service. Section XI of the ASME Boiler and Pressure Vessel Code is applicable for evaluation of nuclear power plant components in service. This Section of the Code does not specifically deal with wall thinning of the piping components. Code Case N-597 provides guidelines for evaluation for continued service for Class 2 and Class 3 piping components. For Class 1 piping components, this Code Case suggests that the plant owner should develop the methodology and criteria for evaluation. This paper presents methodology and procedure for establishing the remaining life and assessment of Class 1 piping components experiencing wall thinning effects. In this paper, the rules of NB-3600 and NB-3220 and Code Case N-597 have been utilized for assessment of the components for continued service. Details of various considerations, criteria and methodology for assessment of the remaining life and adequacy for continued service are provided.

Life Extension of Nuclear Power Plants: World Situation and the USA Case

2010 ◽  
pp. 50-56 ◽  
Author(s):  
Pablo T. León ◽  
Loreto Cuesta ◽  
Eduardo Serra ◽  
Luis Yagüe
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Life Extension ◽  
The Usa

Periodic Materials-Based 3D Seismic Base Isolators for Nuclear Power Plants

2014 ◽  
Author(s):  
Y. Yan ◽  
A. Laskar ◽  
Z. Cheng ◽  
F. Menq ◽  
Y. Tang ◽  
...  
Keyword(s):  
Earthquake Engineering ◽  
Structural Damage ◽  
Nuclear Power ◽  
Power Plants ◽  
Seismic Waves ◽  
Natural Frequencies ◽  
Field Tests ◽  
Band Gaps ◽  
Solid State Physics ◽  
Periodic Materials

The concept of periodic materials, based on solid state physics theory, is applied to earthquake engineering. The periodic material is a material which possesses distinct characteristics that do not allow waves with certain frequencies to be transmitted through; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. In designing a periodic foundation, the first step is to match band gaps of the periodic foundation with the natural frequencies of the superstructure. This is an iterative process. Starting with a design of the periodic foundation, the band gaps are identified by performing finite element analyses using ABAQUS. This design process is repeated until the band gaps match natural frequencies of the superstructure, and the field tests of a scaled specimen are conducted to validate the design. This is an on-going research project. Presented in this paper are the preliminary results, which show that the three dimensional periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitations.

Seismic Fragility of Piping Nozzles in Nuclear Power Plants: A Case for Updating the Current State-of-Practice

2021 ◽  
Author(s):  
Abhinav Gupta ◽  
Ankit Dubey ◽  
Sunggook Cho
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Seismic Analysis ◽  
Nuclear Industry ◽  
Life Extension ◽  
Seismic Loads ◽  
Thermal Loads ◽  
Loss Of Coolant Accident ◽  
Piping Systems ◽  
Recent Developments

Abstract Nuclear industry spends enormous time and resources on designing and managing piping nozzles in a plant. Nozzle locations are considered as a potential location for possible failure that can lead to loss of coolant accident. Industry spends enormous time in condition monitoring and margin management at nozzle locations. Margins against seismic loads play a significant role in the overall margin management. Available margins against thermal loads are highly dependent upon seismic margins. In recent years, significant international collaboration has been undertaken to study the seismic margin in piping systems and nozzles through experimental and analytical studies. It has been observed that piping nozzles are highly overdesigned and the margins against seismic loads are quite high. While this brings a perspective of sufficient safety, such excessively high margins compete with available margins against thermal loads particularly during the life extension and subsequent license renewal studies being conducted by many plants around the world. This paper focuses on identifying and illustrating two key reasons that lead to excessively conservative estimates of nozzle fragilities. First, it compares fragilities based on conventional seismic analysis that ignores piping-equipment-structure interaction on nozzle fragility with the corresponding assessment by considering such interactions. Then, it presents a case that the uncertainties considered in various parameters for calculating nozzle fragility are excessively high. The paper identifies a need to study the various uncertainties in order to achieve a more realistic quantification based on recent developments in our understanding of the seismic behavior of piping systems.

Chapter 2 Seismic hazard

2020 ◽  
Vol 29 (1) ◽  
pp. 43-60 ◽  
Author(s):  
R. M. W. Musson
Keyword(s):  
Seismic Hazard ◽  
Structural Damage ◽  
Nuclear Power ◽  
Power Plants ◽  
Earthquake Hazard ◽  
Moment Magnitude ◽  
Construction Site ◽  
Fault Surface ◽  
Life Threatening ◽  
The Uk

AbstractIt is often thought that earthquakes do not occur in the UK; however, the seismicity of the UK is usually classified as low-to-moderate. On average, a magnitude 3.2 Mw moment magnitude or larger earthquake occurs once per year, and 4.2 Mw or larger every 10 years. The latter is capable of causing non-structural damage to property. The damage caused by British earthquakes is generally not life-threatening, and no-one has been killed in a British earthquake (at the time of writing, May 2013) since 1940. Damage is caused by shaking, not by ground rupture, so the discovery of a fault surface trace at a construction site is not something to be worried about as far as seismic hazard is concerned. For most ordinary construction in the UK, earthquake hazard can be safely discounted; this is not the case with high-consequence facilities such as dams, bridges and nuclear power plants.

European Standard on Small Punch Testing of Metallic Materials

2017 ◽  
Author(s):  
Matthias Bruchhausen ◽  
Tim Austin ◽  
Stefan Holmström ◽  
Eberhard Altstadt ◽  
Petr Dymacek ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Test Methods ◽  
Test Method ◽  
Life Extension ◽  
Tensile Fracture ◽  
Metallic Materials ◽  
Destructive Testing ◽  
Small Punch ◽  
Punch Test

Life extension of aging nuclear power plant components requires knowledge of the properties of the service-exposed materials. For instance, in long term service the tensile and creep properties might decline and the ductile-to-brittle transition temperature (DBTT) might shift towards higher temperatures. Monitoring of structural components in nuclear power plants receives much attention — in particular in the context of lifetime extension of current plants, where the amount of material available for destructive testing is limited. Much effort has therefore been invested in the development of miniature testing techniques that allow characterizing structural materials with small amounts of material. The small punch (SP) test is one of the most widely used of these techniques. It has been developed for nuclear applications but its use is spreading to other industries. Although the SP technique has been used for more than 30 years, there is currently no standard covering its most widely used applications. Within the auspices of ECISS TC 101 “Test methods for steel (other than chemical analysis)” WG 1 is currently developing an EN standard on the “Small Punch Test Method for Metallic Materials”. The standard will address small punch testing for the determination of tensile/fracture properties as well as small punch creep testing. This paper gives an overview of the state-of-the art of the SP tests and describes the scope of the standard under development.

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