Life Prediction and Monitoring of Nuclear Power Plant Components for Service-Related Degradation

2000 ◽  
Vol 123 (1) ◽  
pp. 58-64 ◽  
Author(s):  
Fredric A. Simonen ◽  
Stephen R. Gosselin
Keyword(s):  
Life Prediction ◽  
Nuclear Power ◽  
Fatigue Crack Initiation ◽  
Operating Experience ◽  
Degradation Mechanisms ◽  
Original Design ◽  
Structural Degradation ◽  
Plant Safety ◽  
Degradation Data ◽  
Design Life

This paper describes industry programs to manage structural degradation and to justify continued operation of nuclear components when unexpected degradation has been encountered due to design materials and/or operational problems. Other issues have been related to operation of components beyond their original design life in cases where there is no evidence of fatigue crack initiation or other forms of structural degradation. Data from plant operating experience have been applied in combination with inservice inspections and degradation management programs to ensure that the degradation mechanisms do not adversely impact plant safety. Probabilistic fracture mechanics calculations are presented to demonstrate how component failure probabilities can be managed through augmented inservice inspection programs.

Energy in the 1980s - Operational experience in nuclear power stations

1974 ◽  
Vol 276 (1261) ◽  
pp. 571-586
Keyword(s):  
Nuclear Power ◽  
Nuclear Energy ◽  
Large Scale ◽  
Electrical Power ◽  
Operating Experience ◽  
Operational Experience ◽  
Original Design ◽  
Safety Requirements ◽  
Design Concepts ◽  
Power Stations

From the first self-sustaining nuclear reaction to the present day represents a span of three decades: within that time large-scale generation of electrical power from nuclear energy has become acknowledged as economic, safe and environmentally acceptable. Within the U .K . 10% of electricity consumed is of nuclear origin. Some of the C.E.G.B. reactors have been in service for over 10 years. The operating experience that has been gained shows how the original design concepts have been ultimately developed. Some of the difficulties encountered and the engineering solutions are presented. Operating experience feeds back to the design philosophy and safety requirements for future nuclear plant. In this way a foundation is provided for the further exploitation of what must become a major source of energy in the next decade.

Operational Impacts and Consequences of Piping Component Failure: A Review of Operating Experience Data As Recorded in CODAP

2018 ◽  
Author(s):  
Braedon Carr ◽  
Bengt Lydell ◽  
Jovica R. Riznic
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Cooling Water ◽  
Operating Experience ◽  
Transport Systems ◽  
Volume Control ◽  
Operational Experience ◽  
Component Failure ◽  
Plant Safety ◽  
Operational Impacts

Water chemistry plays an important part in maintaining corrosion resistance in water transport systems throughout nuclear power plants (NPP’s). Small changes in liquid chemistry such as pH, borate concentration, or build-up of crud in reactor cooling water can result in rapid degradation or damage to components and lead to unexpected failures. The Chemical and Volume Control System (CVCS) and Reactor Water Cleanup System (RWCU) are responsible for maintaining these parameters at appropriate levels, and so failure of either of these systems can result in unnecessary stresses on many other reactor systems due to resulting transients. While the major components of these systems all have sufficient redundancy to prevent major accidents, failure of components in these systems can result in failure of other redundant components and affect plant safety [1]. The CVCS and RWCU systems have experienced aging related degradations and failures in the past, and although they have not affected the system’s emergency functions, they have resulted in unnecessary actuation of related systems, and reactor shutdowns [1]. Reactor shutdowns can result in large changes in reactor coolant chemistry such as oxygen and borate concentration transients, and the build-up of corrosion products which can’t be as easily removed during periods of reactor shutdown [2]. In the following analysis of Component Operational Experience Degradation and Ageing Program (CODAP) experience data; causes, impacts, and preventative actions as recorded in CODAP are examined for degradation events which took place in the CVCS and RWCU, of PWRs and BWRs, respectively. The analysis will demonstrate the usefulness of CODAP in examining reactor component failure trends, as well as discuss insights on improvement for the program.

scholarly journals Research On Optimization Method of Fatigue Analysis for Nuclear Pipeline

2021 ◽  
Vol 257 ◽  
pp. 02017
Author(s):  
Yuan Liang ◽  
Liu Shengyong ◽  
Yang Jie ◽  
Zhou Qiang ◽  
Zhang Guihe
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Optimization Method ◽  
Fatigue Analysis ◽  
Analysis Method ◽  
Pressurized Water Reactor ◽  
Original Design ◽  
Pressurized Water ◽  
Design Life ◽  
License Application

The initial design life of nuclear power plant is 40 years. In 60 year life extending license application, the fatigue of component should be evaluated under the influence of the fatigue factors of the pressurized water reactor coolant environment. Because the original design used a more conservative analysis method, the result could not meet the requirement of Cumulative usage fatigue factor of RCC-M. An optimizing analysis method is studied, and as an example of application, optimizing fatigue analysis of Safety Injection Nozzle of Main Coolant Line is performed. The evaluation results show that the optimized fatigue analysis results meet the requirements of RCC-M.

IAEA Activities on Concrete Ageing in Containment and Other Structures in Nuclear Power Plants

2013 ◽  
Author(s):  
Ki-Sig Kang ◽  
John H. Moore
Keyword(s):  
Service Life ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Concrete Structures ◽  
Operating Experience ◽  
Life Extension ◽  
Spent Fuel ◽  
Design Life ◽  
Ageing Management

Significant industry developments over the past decade have placed concrete ageing at the forefront of life extension decisions related to nuclear power plants. Recent issues encountered include alkali–silica reactivity in concrete, delamination events, larger than anticipated loss of pre-stressing force, spent fuel pool leakage, corrosion of steel reinforcement in water intakes, and others. Concrete structures at nuclear power plants are being asked to perform for longer periods than originally design life. Utilities around the world are investigating plant service life extensions (with 60 years or more total being a quoted target), and for some projects delayed construction schedules, and/or decommissioning strategies that involve the use of containment as a “safe store” for periods of up to 100 years, mean that containment buildings and other concrete structures often have to perform their functions for a time period significantly greater than their initial design life. Newer plants are designed with design lives of 60 years or more. Concrete is a durable material and its performance as part of the containment function in NPPs has been good. However, experience shows that ageing degradation of concrete structures, often caused or accelerated by factors such as faulty design, use of unsuitable or poor quality materials, improper construction, exposure to aggressive environments, excessive structural loads, and accident conditions, can impair its safety functions and increase risks to public health and safety. Effective ageing management of concrete containment buildings and other concrete structures is therefore required to ensure their fitness-for-service throughout the plant service life and during decommissioning. The paper presented will present current International Atomic Energy Agency activities in the area of concrete structures and ageing management, and point to where guidelines and best practises related to concrete structure ageing management, relevant operating experience, and applicable codes and standards may be located.

scholarly journals Low-Cycle Fatigue Crack Initiation Simulation and Life Prediction of Powder Superalloy Considering Inclusion-Matrix Interface Debonding

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4018
Author(s):  
Shuming Zhang ◽  
Yuanming Xu ◽  
Hao Fu ◽  
Yaowei Wen ◽  
Yibing Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Interface Debonding ◽  
Damage Evolution Equation ◽  
Finite Element Software

From the perspective of damage mechanics, the damage parameters were introduced as the characterizing quantity of the decrease in the mechanical properties of powder superalloy material FGH96 under fatigue loading. By deriving a damage evolution equation, a fatigue life prediction model of powder superalloy containing inclusions was constructed based on damage mechanics. The specimens containing elliptical subsurface inclusions and semielliptical surface inclusions were considered. The CONTA172 and TARGE169 elements of finite element software (ANSYS) were used to simulate the interfacial debonding between the inclusions and matrix, and the interface crack initiation life was calculated. Through finite element modeling, the stress field evolution during the interface debonding was traced by simulation. Finally, the effect of the position and shape size of inclusions on interface debonding was explored.

scholarly journals Critical Review of Polymeric Building Envelope Materials: Degradation, Durability and Service Life Prediction

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 299
Author(s):  
Marzieh Riahinezhad ◽  
Madeleine Hallman ◽  
J-F. Masson
Keyword(s):  
Climate Change ◽  
Service Life ◽  
Critical Review ◽  
Life Prediction ◽  
Building Envelope ◽  
Service Life Prediction ◽  
Degradation Mechanisms ◽  
Material Component ◽  
Aging Conditions ◽  
Environmentally Sound

This paper provides a critical review of the degradation, durability and service life prediction (SLP) of polymeric building envelope materials (BEMs), namely, claddings, air/vapour barriers, insulations, sealants, gaskets and fenestration. The rate of material deterioration and properties determine the usefulness of a product; therefore, knowledge of the significant degradation mechanisms in play for BEMs is key to the design of proper SLP methods. SLP seeks to estimate the life expectancy of a material/component exposed to in-service conditions. This topic is especially important with respect to the potential impacts of climate change. The surrounding environment of a building dictates the degradation mechanisms in play, and as climate change progresses, material aging conditions become more unpredictable. This can result in unexpected changes and/or damages to BEMs, and shorter than expected SL. The development of more comprehensive SLP methods is economically and environmentally sound, and it will provide more confidence, comfort and safety to all building users. The goal of this paper is to review the existing literature in order to identify the knowledge gaps and provide suggestions to address these gaps in light of the rapidly evolving climate.

scholarly journals Aircraft Impact Effects on an Aged NPP

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 816
Author(s):  
Rosa Lo Frano
Keyword(s):  
Nuclear Power ◽  
Military Aircraft ◽  
Residual Resistance ◽  
Plant Safety ◽  
Need To Evaluate ◽  
Target Wall ◽  
Impact Area ◽  
Wall Perforation ◽  
The Impact ◽  
Loss Of Strength

The impact of an aircraft is widely known to be one of the worst events that can occur during the operation of a plant (classified for this reason as beyond design). This can become much more catastrophic and lead to the loss of strength of/collapse of the structures when it occurs in the presence of ageing (degradation and alteration) materials. Therefore, since the performance of all plant components may be affected by ageing, there is a need to evaluate the effect that aged components have on system performance and plant safety. This study addresses the numerical simulation of an aged Nuclear Power Plant (NPP) subjected to a military aircraft impact. The effects of impact velocity, direction, and location were investigated together with the more unfavorable conditions to be expected for the plant. The modelling method was also validated based on the results obtained from the experiments of Sugano et al., 1993. Non-linear analyses by means of finite element (FE) MARC code allowed us to simulate the performance of the reinforced concrete containment building and its impact on plant availability and reliability. The results showed that ageing increases a plant’s propensity to suffer damage. The damage at the impact area was confirmed to be dependent on the type of aircraft involved and the target wall thickness. The greater the degradation of the materials, the lower the residual resistance capacity, and the greater the risk of wall perforation.

Effect of Creep on the Residual Stresses in Tube-to-Tubesheet Joints

2010 ◽  
Author(s):  
Nor Eddine Laghzale ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Contact Pressure ◽  
Analytical Model ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Environmental Safety ◽  
Maintenance Cost ◽  
Joint Interface ◽  
Plant Safety ◽  
Material Creep ◽  
Nuclear Power Plant Safety

Steam generators are the subject of major concern in nuclear power plant safety. Within these generators, in addition to the structural integrity, the gross tightness barrier, which separates the primary and secondary circuits, is primarily ensured by the presence of a residual contact pressure at the tube-to-tubesheet joint interface. Any leakage is unacceptable, and its consequences are very heavy in terms of the human and environmental safety as well as maintenance cost. Some studies have been conducted to understand the main reasons for such a failure. However, no analytical model able to predict the attenuation of the residual contact pressure under the effect of material creep relaxation behavior. The development of a simple analytical model able to predict the change of the residual contact pressure as a function of time is laid out in this paper. The results from the analytical model are checked and compared with those of finite elements.

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