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Engineering Fundamentals CBTPrintout of CBT Content for Reference Purposes Only Reference CBT:Basic Atomic and Nuclear Physics V 1.01019164

Engineering Fundamentals CBT:Printout of CBT Content for Reference Purposes Only Reference CBT:

Basic Atomic and Nuclear Physics V 1.01019164 June 2009

EPRI Project Manager Ken Caraway

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1338 PO Box 10412, Palo Alto, California 94303-0813 USA 800.313.3774 650.855.2121 askepri@epri.com www.epri.com

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIESTHIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM: (A) MAKES ANY WARRANTY OR REPRESENTATION WHATSOEVER, EXPRESS OR IMPLIED, (I) WITH RESPECT TO THE USE OF ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT, INCLUDING MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, OR (II) THAT SUCH USE DOES NOT INFRINGE ON OR INTERFERE WITH PRIVATELY OWNED RIGHTS, INCLUDING ANY PARTY'S INTELLECTUAL PROPERTY, OR (III) THAT THIS DOCUMENT IS SUITABLE TO ANY PARTICULAR USER'S CIRCUMSTANCE; OR (B) ASSUMES RESPONSIBILITY FOR ANY DAMAGES OR OTHER LIABILITY WHATSOEVER (INCLUDING ANY CONSEQUENTIAL DAMAGES, EVEN IF EPRI OR ANY EPRI REPRESENTATIVE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES) RESULTING FROM YOUR SELECTION OR USE OF THIS DOCUMENT OR ANY INFORMATION, APPARATUS, METHOD, PROCESS, OR SIMILAR ITEM DISCLOSED IN THIS DOCUMENT. ORGANIZATION(S) THAT PREPARED THIS DOCUMENT EPRI

NOTEFor further information about EPRI, call the EPRI Customer Assistance Center at 800.313.3774 or e-mail askepri@epri.com. Electric Power Research Institute, EPRI, and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute, Inc. Copyright 2009 Electric Power Research Institute, Inc. All rights reserved.

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PRODUCT DESCRIPTIONSummary This document provides a printout of the CBT content for use as a reference document only. Students are encouraged to use the CBT as animations, flash video, and interactive features are intended to enhance their learning experience. NOTE: The CBT should be used to validate information as errors may have been introduced when converting the graphics, equations, etc. Abstract The Basic Atomic and Nuclear Physics Version 1.0 module of Engineering Fundamentals provides a basic overview of this topic applicable to all engineering disciplines beginning their career in the nuclear power industry. Description The Basic Atomic and Nuclear Physics module covers basic atomic structure, fission, radioactivity, reactor operation, and nuclear safety. This course will help new engineers understand how their work might impact reactor operations and nuclear safety. This module is intended for use as orientation training for new engineering support personnel. Software Requirements Windows 2000 SP2, Windows XP, Windows Vista Application, Value and Use Allows engineering support personnel to review the content when they desire and at their own pace Uses interactive features and graphics to illustrate key concepts & enhance training Keywords Training Fundamentals Atomic structure Nuclear physics Radioactivity Fission Reactor operation Reactor systems Nuclear safety

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ACKNOWLEDGEMENTSEPRI would like to acknowledge the following individuals for their active participation and significant contributions toward the development of this training course: Ken Caraway Jack Feimster Nate Granger Beth Hughes Don Lesnick Joe Montague Henry Nicholson Liz Sisk Terry Stuchlik EPRI Exelon Corporation Wolf Creek Nuclear Operating Corporation Handshaw, Inc. Exelon Corporation Dominion Duke Energy Corporation EPRI Wolf Creek Nuclear Operating Corporation

CONTENTS1 INTRODUCTION TO BASIC ATOMIC AND NUCLEAR PHYSICS ......................................1-1 2 BASIC ATOMIC STRUCTURE ..................................... ERROR! BOOKMARK NOT DEFINED. 3 THE FISSION PROCESS AND NEUTRON INTERACTIONSERROR! BOOKMARK NOT DEFINED. 4 RADIOACTIVITY .......................................................... ERROR! BOOKMARK NOT DEFINED. 5 REACTOR OPERATION .............................................. ERROR! BOOKMARK NOT DEFINED. 6 NUCLEAR SAFETY ..................................................... ERROR! BOOKMARK NOT DEFINED.

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1INTRODUCTION TO BASIC ATOMIC & NUCLEAR PHYSICSIntroduction

Welcome to the Basic Atomic and Nuclear Physics course. In this course, you will learn about basic atomic structure, radioactivity, fission, reactor operation, and nuclear safety. Regardless of your discipline, you can make changes that affect reactor operations and nuclear safety in your day-to-day job. Changes that may affect operations include instrumentation and control changes, electrical and/or mechanical system alignment or availability, and introduction of foreign material (items unintended for system use) including coatings inside containment. You must be aware of how all equipment and systems in the plant might be impacted by what you and others do. After completing this lesson, you will be able to:

Describe how a nuclear power plant generates electricity Describe the design differences between the two types of reactor systems typically used in the United States

If you are not familiar with the navigation features used in this course, click the About tab to review the navigation information.

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Nuclear Steam Supply Systems

First, lets take a high-level look at how a nuclear power plant works. The purpose of a nuclear power plant is to produce steam that is used to generate electricity. The underlying concept behind this Nuclear Steam Supply System (NSSS), as it is called, is straightforward. Nuclear fission indirectly creates heat, which is then used to generate steam. From this point, a nuclear power plant functions very much like a fossil fuel generating plant. The steam flows through turbines, rotating a shaft, which then turns the generator to produce electricity. Each component and system in a nuclear power plant is designed and must be operated to ensure that fission remains a safe, economic, reliable source of power. Although the basic premise is simple, the NSSS is a complex system requiring a fundamental understanding of certain aspects of nuclear physics.The diagram below shows the main components of a PWR NSSS system. Roll your mouse over each component to identify its function. (Note: This function will not work in this Word document.)

Fuel

Let's take a closer look at how an NSSS works. The fuel for an NSSS is typically enriched uranium that fissions easily with proper geometry and moderation. For U.S. nuclear plants, fuel is typically contained in small, cylindrical pellets, which measure approximately 0.4 inch in diameter by 0.5 inch long. Pellets have small diameters so that heat can be removed effectively. One pellet of uranium can generate as much electricity as 4 barrels of oil or 1.3 tons of coal. Clearly, the reactor fuel has high power density (power per unit volume) compared to fossil fuels.

The pellets are stacked one on top of another to form a 12-foot long column and placed into a sealed tube. The tube is called a fuel rod and is cladded with a wall thickness typically about 0.04 inches thick. The cladding is made of a zirconium alloy that transmits heat, absorbs few neutrons, and is non-corrosive, characteristics important for maintaining the integrity of the tubes while efficiently transferring the heat and neutrons produced by fission. The cladding provides the first layer in the defensein-depth design for keeping radioactive fission products contained. A set of fuel rods is bundled in a square lattice called a fuel assembly. Assemblies are placed side-by-side in a nearly cylindrical array inside a large steel vessel called the reactor vessel, which is part of the Reactor Coolant System boundary - the second barrier to radioactivity. The total number of fuel assemblies depends on the type and power level of the reactor.

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Moderator and Coolant

Interactions of free neutrons with nuclei in the fuel can result in fission. Fission occurs when a free neutron collides with a nucleus, is absorbed by the nucleus, and causes the nucleus to split into two fragments and emit additional neutrons. During fission, energy is released in the form of heat. If the newly emerged neutrons cause additional fissions, a chain reaction results. Self-sustained fission chain reactions generate a steady supply of heat, the source of nuclear power in an NSSS. However, neutrons born from fission typically have high kinetic energy and tend not to cause fission. Therefore, to facilitate fission of uranium, neutrons must be slowed down. This is achieved by using a moderator, which surrounds the fuel rods. Fast neutrons bounce off nuclei of similar mass in the moderator. With each collision, the neutrons lose some of their kinetic energy and start slowing down. In U.S. reactors, the moderator is water, which also serves as the coolant. The heat from fission transfers from the fuel rods to the coolant, which is used for steam generation, but also keeps the fuel from overheating. Reactors that use "light" water (no neutron in the hydrogen atom) as moderator and coolant are called light water reactors, or LWRs. In other countries such as Canada, other media are often used for the coolant and moderator, including deuterium (known as "heavy water"). In those cases, the moderator and coolant may be located in physically separate volumes.

Controlling Fission Rate

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