3/2003 rev 1 i.3.8&10 – slide 1 of 23 part i review of fundamentals module 3interaction of...
TRANSCRIPT
3/2003 Rev 1 I.3.8&10 – slide 1 of 23
Part I Review of Fundamentals
Module 3 Interaction of Radiation with Matter
Session 8&10 Neutron Activation
Session I.3.8&10
IAEA Post Graduate Educational CourseRadiation Protection and Safety of Radiation Sources
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Introduction
Neutron activation will be discussed
Students will learn about principles of neutron activation, the activation equation, concept of maximum or saturation activity, and solve a problem
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Content
Importance of neutron activation to health physics
Production rate of an isotope under neutron bombardment
Activation equation
Concept of maximum or saturation activity
Solve a problem
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Overview
Principles of neutron activation of stable isotopes will be discussed
Health physics significance of neutron activation will be discussed
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Examples of Importance of Neutron Activation
Production of isotopes (for example 60Co, 192Ir, etc.)
Accident dosimetry (for example 24Na in blood)
Crime detection in forensic medicine
(for example Napoleon’s hair)
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Activation analysis for measurement of trace elements
Activation products in a reactor are major sources of radiation exposure to workers (for example 60Co)
Activation products can give a radiation dose to members of the public (e.g. direct gamma radiation from 16N in steam from a BWR)
Examples of Importance of Neutron Activation
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Determination of fast neutron radiation component at Hiroshima
Fast neutron activation of Cu in building materials created 63Ni by reaction
63Cu (n, p) 63Ni
Accelerator mass spectrometry of 63Ni (half-life = 100 years)
Examples of Importance of Neutron Activation
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N(t) = No(1 - e-t)
Equation for RadionuclideProduction by Neutron Activation
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N(t) = No (1 - e-t)A(t) =
Activation Equation Expressedin Terms of Activity
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for t << 1
e(-t ) = 1 - t
Useful Rule of Thumb forSimplifying Exponential Terms
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Problem 1
One gram of cobalt is introduced into a neutron flux of 1 x 1014 neutrons cm-2 sec-1. Calculate:
the resultant activity of 60Co in TBq after one year and
the maximum (saturation) activity of 60Co
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Problem 1 – Given Conditions
Given:
% abundance of 59Co = 100%
# of atoms in 1 mole of 59Co = 6.02 x 1023
cross section = 19 barns
1 barn = 10-24 cm2
half-life of 60Co = 5.2 years
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Solution to Problem 1
Activity of 60Co is given by A = No (1 - e-t)
= 1014 neutrons cm-2 second-1
= 19 x 10-24 cm2
No = 1 g x 6.02 x 1023 atoms mole-1 x = 1.02 x 1022 atoms
t = x 1 y = 0.13
(1 - e-t) = (1 - e-0.13) = (1 - 0.878) = 0.12
1 mole59 g
0.6935.2 y
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Solution to Problem 1
Solving for A we have:
(a) A = (1014) x (19 x 10-24) x (1.02 x 1022) x (0.12) = 2.33x 1012 dps of 60Co = 2.33 TBq
60Co
(b) The maximum or saturation activity of 60Co is given by: A() = N = No
since (1 - exp-) = 1
No = (1014) x (19 x 10-24) x (1.02 x 1022) = 1.94 x 1013 dps = 19.4 TBq 60Co
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Summary
Neutron activation was discussed
We learned about the health physics significance and principles of neutron activation, the activation equation, concept of maximum or saturation activity, and solved a problem dealing with radionuclide production by neutron activation
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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)
Attix, F. H., Introduction to Radiological Physics and Radiation Dosimetry, Wiley and Sons, Chichester (1986)
Firestone, R.B., Baglin, C.M., Frank-Chu, S.Y., Eds., Table of Isotopes (8th Edition, 1999 update), Wiley, New York (1999)