1. 3/2003 Rev 1 I.3.8&10 – slide 1 of 23 Part I Review of Fundamentals Module 3Interaction of Radiation with Matter Session 8&10Neutron Activation Session I.3.8&10 IAEA Post Graduate Educational Course Radiation Protection and Safety of Radiation Sources

2. 3/2003 Rev 1 I.3.8&10 – slide 2 of 23 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

3. 3/2003 Rev 1 I.3.8&10 – slide 3 of 23 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

4. 3/2003 Rev 1 I.3.8&10 – slide 4 of 23 Overview  Principles of neutron activation of stable isotopes will be discussed  Health physics significance of neutron activation will be discussed

5. 3/2003 Rev 1 I.3.8&10 – slide 5 of 23 Neutron Capture in 23 Na 23 Na (n,  ) 24 Na

6. 3/2003 Rev 1 I.3.8&10 – slide 6 of 23 Examples of Importance of Neutron Activation  Production of isotopes (for example 60 Co, 192 Ir, etc.)  Accident dosimetry (for example 24 Na in blood)  Crime detection in forensic medicine (for example Napoleon’s hair)

7. 3/2003 Rev 1 I.3.8&10 – slide 7 of 23  Activation analysis for measurement of trace elements  Activation products in a reactor are major sources of radiation exposure to workers (for example 60 Co)  Activation products can give a radiation dose to members of the public (e.g. direct gamma radiation from 16 N in steam from a BWR) Examples of Importance of Neutron Activation

8. 3/2003 Rev 1 I.3.8&10 – slide 8 of 23  Determination of fast neutron radiation component at Hiroshima  Fast neutron activation of Cu in building materials created 63 Ni by reaction 63 Cu (n, p) 63 Ni 63 Cu (n, p) 63 Ni  Accelerator mass spectrometry of 63 Ni (half-life = 100 years) Examples of Importance of Neutron Activation

9. 3/2003 Rev 1 I.3.8&10 – slide 9 of 23 Concept of Reaction Rate Neutron Bombardment

10. 3/2003 Rev 1 I.3.8&10 – slide 10 of 23 =  N o - N dN dt Differential Equation for Neutron Activation

11. 3/2003 Rev 1 I.3.8&10 – slide 11 of 23 N(t) =  N o (1 - e - t ) Equation for Radionuclide Production by Neutron Activation

12. 3/2003 Rev 1 I.3.8&10 – slide 12 of 23 N(t) =  N o (1 - e - t ) A(t) = Activation Equation Expressed in Terms of Activity

13. 3/2003 Rev 1 I.3.8&10 – slide 13 of 23 for t << 1 e (- t ) = 1 - t Useful Rule of Thumb for Simplifying Exponential Terms

14. 3/2003 Rev 1 I.3.8&10 – slide 14 of 23 N(  ) =  N o Equation for Maximum or Saturation Activity

15. 3/2003 Rev 1 I.3.8&10 – slide 15 of 23 Buildup of a Radionuclide Under Neutron Bombardment

16. 3/2003 Rev 1 I.3.8&10 – slide 16 of 23 Buildup and Decay Following Neutron Activation

17. 3/2003 Rev 1 I.3.8&10 – slide 17 of 23 Time to Reach Saturation Function of Product Half-Life

18. 3/2003 Rev 1 I.3.8&10 – slide 18 of 23 Problem 1 One gram of cobalt is introduced into a neutron flux of 1 x 10 14 neutrons cm -2 sec -1. Calculate:  the resultant activity of 60 Co in TBq after one year and  the maximum (saturation) activity of 60 Co

19. 3/2003 Rev 1 I.3.8&10 – slide 19 of 23 Problem 1 – Given Conditions Given: % abundance of 59 Co = 100% # of atoms in 1 mole of 59 Co = 6.02 x 10 23 cross section = 19 barns 1 barn = 10 -24 cm 2 half-life of 60 Co = 5.2 years

20. 3/2003 Rev 1 I.3.8&10 – slide 20 of 23 Solution to Problem 1 Activity of 60 Co is given by A =  N o (1 - e - t )  = 10 14 neutrons cm -2 second -1  = 19 x 10 -24 cm 2 N o = 1 g x 6.02 x 10 23 atoms mole -1 x = 1.02 x 10 22 atoms = 1.02 x 10 22 atoms t = x 1 y = 0.13 t = x 1 y = 0.13 (1 - e - t ) = (1 - e -0.13 ) = (1 - 0.878) = 0.12 1 mole 59 g 0.693 5.2 y

21. 3/2003 Rev 1 I.3.8&10 – slide 21 of 23 Solution to Problem 1 Solving for A we have: (a) A = (10 14 ) x (19 x 10 -24 ) x (1.02 x 10 22 ) x (0.12) = 2.33x 10 12 dps of 60 Co = 2.33 TBq 60 Co (b)The maximum or saturation activity of 60 Co is given by:A(  ) = N =  N o since (1 - exp - ) = 1  N o = (10 14 ) x (19 x 10 -24 ) x (1.02 x 10 22 ) = 1.94 x 10 13 dps = 19.4 TBq 60 Co = 1.94 x 10 13 dps = 19.4 TBq 60 Co

22. 3/2003 Rev 1 I.3.8&10 – slide 22 of 23 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

23. 3/2003 Rev 1 I.3.8&10 – slide 23 of 23 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, 6 th 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 (8 th Edition, 1999 update), Wiley, New York (1999)