Material Properties & Corrosion for Nuclear Plants

A. Bhatia, B.E.

Course Outline

The purpose of this course is to briefly introduce several material properties and failure modes. A better understanding of these failure mechanisms will enable more appropriate decisions when selecting materials for a particular application. Even a basic knowledge and awareness can help design engineers to be better equipped in delaying or preventing the failure of a material or component.

This 5 - hour course discusses properties and behavior of materials related to nuclear power reactors. This course is based entirely on CNSC training course, Science & Reactor Fundamentals, titled “Materials” and is extracted from Canteach knowledge repository - http://canteach.candu.com/ .

This course  includes a multiple-choice quiz at the end, which is designed to enhance the  understanding of the course materials.

Learning Objective 

The course focuses on material properties and corrosion phenomenon. At the conclusion of this course, the reader will:

• Define terms as they relate to materials: mechanical stress and strain, hoop stress, thermal expansion, differential thermal expansion, thermal shock & residual stress;
• Describe factors which cause mechanical and thermal stress in a component;
• Explain the consequences of exceeding stress limits in materials;
• Explain why heating and cool down rates are limited;
• Explain the differences between ductile and brittle fracture;
• Explain why a material exhibiting a ductile/brittle transition temperature has operating limitations with respect to temperature;
• Explain why a large shaft becomes deformed when at rest and why rolling a large shaft prior to operation reduces the deformation;
• Describe creep, fatigue failure and work hardening;
• Describe the erosion, wear or surface failure of materials;
• Describe the following corrosion types: uniform, galvanic, pitting and crevice, stress corrosion cracking, erosion & microbiologically induced;
• Explain the importance of pH control in carbon steel and stainless steel based systems;
• Explain the importance of conductivity control, and describe the typical methods used to maintain proper control;
• Define the term stress corrosion cracking (SCC), and state the conditions required to promote SCC;
• Explain how scale can be formed on boiler tubes, state the adverse consequences of scale formation, and state the methods used to minimize scale formation;
• State the effect of radiation on materials: oils and greases, plastics, metals & concrete;
• Describe the process of hydrogen embrittlement and the occurrence of delayed hydride cracking and blistering of pressure tubes, including the factors affecting it; and
• Explain how temperature cycling and reduced heat transport pressure can be used to minimize the potential for delayed hydride cracking in pressure tubes during start-up and cool-down.
  

Intended Audience

This course is applicable to mechanical engineers, metallurgists, process engineers, R&D personnel, production engineers, safety engineers, operation and maintenance personal.

Benefit to Attendees

Attendee of this course will get to know more about material properties, and the characteristics that influence wear, fatigue, stress and consequent failure. The course will be extremely helpful to the amateur engineers who desire to build on their design experience and the skilled professionals who have learnt the trade informally on the job.

Course Introduction

The understanding of the structure and properties of metals, stress mechanisms, failure modes and the characteristics determine their usefulness for a specific application. Often, materials are subject to variable forces (loads). The mechanical engineer calculates these forces to establish the service that can be expected and material scientists experiment to determine how materials deform (elongate, compress, and twist) or break as a function of applied load, time, temperature, and other conditions.

This course discusses properties and behavior of materials related to nuclear power reactors.

Course Content

This course is in the following PDF document:

Material Properties & Corrosion for Nuclear Plants

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.

Course Summary

Some general causes for failure are structural loading, wear, corrosion, and latent defects. Because most engineering materials contain discontinuities most metal fatigue cracks initiate from discontinuities in highly stressed regions of the component. Failure can occur in systems with moving or non-moving parts. In systems with moving parts, friction often leads to material degradation such as wear, and collisions between two components can result in surface or more extensive material damage. Systems with non-moving parts are also prone to material failure, especially when certain types of materials operate over a broad range of pressures and are subjected to extreme temperature changes or to high energy radiation environments.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

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DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.

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