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Session I.2.9

Part I Review of Fundamentals

Module 2 Basic Physics and MathematicsUsed in Radiation Protection

Session 9 Nuclear Reactions

IAEA Post Graduate Educational CourseRadiation Protection and Safety of Radiation Sources

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Various examples of nuclear reactions will be discussed

Students will learn about properties of neutrons, nuclear decay processes, cross section, neutron interactions, and various kinds of nuclear reactions including charged particle reactions, spallation, fission and fusion reactions

Introduction

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Content

Properties of neutrons Nuclear decay processes Cross section Neutron interactions Charged particle reactions Spallation Fission Fusion

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Overview

Various kinds of nuclear reactions will be discussed and examples shown

Health physics significance and energy considerations of nuclear reactions will be discussed

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Chadwick, 1932, alpha bombardment

He + Be C + n + Q

Neutron Discovery

Thermal (0.0025 eV)Slow (1 - 100 eV)Epithermal (100 eV – 100 keV)Fast (100 keV – 1 MeV)Ultrafast (>1 MeV)

Neutron Classification

Properties of Neutrons

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Neutron Characteristics symbol - n no charge rest energy 939.507 MeV has a magnetic moment it is a fermion

Neutron Interaction with matter Scattering (2 mechanisms) Absorption (>4 mechanisms)

Properties of Neutrons

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Nuclear ReactionsNuclear Decay

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Nuclear ReactionsAlpha Decay

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Nuclear ReactionsBeta Decay

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Nuclear ReactionsPositron Decay or Electron Capture

Electron Capture

Positron Emission

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Nuclear ReactionsSummary of Major Decay Mechanisms

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Cross Section

where

= cross section

R = number of reactions per unit time per nucleus

I = number of incident particles per unit time per unit area

= RI

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Nuclear ReactionsFast Neutron Interactions

Elastic scattering - neutrons interact with particles of approximately the same mass such as protons (billiard ball analogy)

Occurs in materials rich in hydrogen such as water, wax, concrete

Accounts for about 80% of fast neutron dose to tissue

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Inelastic scattering – neutrons interact with particles of much greater mass, for example, iron (table tennis ball vs bowling ball analogy)

Nuclear ReactionsFast Neutron Interactions

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Nuclear ReactionsElastic Scattering of Neutrons

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Nuclear ReactionsInelastic Scattering of Neutrons

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Neutron Reactions

(n, CP) QHeLiBn 42

73

105

10

CoCon 605910

(n, gamma)

LiMoUUn 1399523692

23592

10 *

(n, fission)

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Nuclear ReactionsNeutron Absorption, Charged Particle

n + 10B 7Li(*) +

7Li(*) 7Li + soft gamma (480 KeV)

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Fission

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Breeding 239Pu from 238U Neutron Capture

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Details of 239U Decay to 239Pu

239U (23.5 min) 239Np (2.3 d) 239Pu

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Nuclear ReactionsCharged Particle Bombardment

p + 68Zn 67Ga + 2n

+ 16O 18F + p + n

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Nuclear ReactionsSpallation

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Spallation Products

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Spallation Produced by Neutrons or Protons

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Nuclear Fusion ReactionsUtilize Isotopes of Hydrogen

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Nuclear ReactionsFusion

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Deuteron – Deuteron Fusion

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Tritium – ProtonProduction from Fusion

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3He with Neutron Production from Fusion

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Fusion - Tokamak

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Energy ProductionReactions in Stars

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CNO Energy ProductionReactions in Stars

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Summary

Various examples of nuclear reactions were discussed

Students learned about properties of neutrons, nuclear decay processes, cross section, neutron interactions, and various kinds of nuclear reactions including charged particle reactions, spallation, fission and fusion

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Where to Get More Information

Cember, H., Johnson, T. E., Introduction to Health Physics, 4th Edition, McGraw-Hill, New York (2008)

Martin, A., Harbison, S. A., Beach, K., Cole, P., An Introduction to Radiation Protection, 6th Edition, Hodder Arnold, London (2012)

Jelley, N. A., Fundamentals of Nuclear Physics, Cambridge University Press, Cambridge (1990)

Firestone, R.B., Baglin, C.M., Frank-Chu, S.Y., Eds., Table of Isotopes (8th Edition, 1999 update), Wiley, New York (1999)