Nuclear Radiation, the chart of nuclides

Nuclear Radiation
The Chart of Nuclides

1. Nuclear Radiation The Chart of Nuclides Experiment 10-Physics Lab. 2120 Younes Sina

2.   To become familiar with the use of the Chart of Nuclides     Objective

3. An up quark has a mass of 0.0047 u and a down quark has a mass of 0.0074 u. up down

4. The decay modes are  - ,  + and electron capture (EC). n p

5. Electron Capture (EC )

6.  +

7. → →

8. Cross Sections Probability of a neutron interaction with a nucleus is depend on the kind of nucleus and the energy of the neutron . In fission reactors thermal neutrons can be absorbed easier than fast neutrons. H 2 0 is an excellent moderator because of the hydrogen nuclei (protons) in the water. As a moderator, D 2 0 is almost as good as normal water and has the added advantage that its neutron absorption cross section is small. Graphite also slows neutrons well, is inexpensive, but burns .

9. A fast neutron is a free neutron with a kinetic energy level close to 1 MeV (speed of 14,000  km/s) A thermal neutron is a free neutron with a kinetic energy of about 0.025 eV (speed of 2.2 km/s)

10. How Do Reactors Work? U-235  +  1 neutron  ======= >      Fragment A  +  Fragment B   +  200 MeV of energy Critical Mass For a chain reaction of nuclear fission, such as that of uranium-235, is to sustain itself, then at least one neutron from each fission must strike another U-235 nucleus and cause a fission. If this condition is just met, then the reaction is said to be "critical" and will continue. The mass of fissile material required to achieve this critical condition is said to be a critical mass. The critical mass depends upon the concentration of U-235 nuclei in the fuel material as well as its geometry. As applied for the generation of electric energy in nuclear reactors, it also depends upon the moderation used to slow down the neutrons. In those reactors, the critical condition also depends upon neutrons from the fission fragments, called delayed neutrons.

11. The neutrons emitted in nuclear fission reactions have high energies, typically in the range of 1 MEV . But the cross section for neutron capture leading to fission is greatest for neutrons of energy around 1 eV , a million times less. Neutrons with energies less than 1 eV are commonly referred to as "thermal neutrons" since they have energies similar to what particles have as a result of ordinary room-temperature thermal energy.

12. Thermal reactors Most fission reactors are thermal reactors that use a neutron moderator to slow down, or thermalize the neutrons produced by nuclear fission. Moderation substantially increases the fission cross section for fissile nuclei such as uranium-235 or plutonium-239. In addition, uranium-238 also has a much lower capture cross section for thermal neutrons, allowing more neutrons to cause fission of fissile nuclei and continue the chain reaction, rather than being captured by 238 U. The combination of these effects allows light water reactors to use low-enriched uranium.

13. Guide for using the Chart of the Nuclides

14. 1 day to 10 days 10 days to 100 days 100 days to 10 years 10 years to 5E8 years > 5E8 years or stable Colors used for half lives (Appear in upper half of nuclide block)

15. 10 barns to 100 barns Colors used for neutron absorption properties (Appear in lower half of nuclide block) 100 barns to 500 barns 500 barns to 1000 barns > 1000 barns

16. H 1.0079 Hydrogen σ a .333, .150 Chemical Element Symbol Atomic Weight (Carbon-123 Scale) Thermal Neutron Absorption Cross Section in Barns, followed by Resonance Integral, in Barns

17. Gray shaded square: (Stable Nuclide)

18. Pd 108 26.46 107.903894 σ γ (.19+8), (5+24E1) Stable Symbol, Mass Number Atom Percent Abundance Thermal Neutron Activation Cross Section in Barns, Leading to( Isomeric+ Ground State),followed by Resonance Integrals Leading to( Isomeric+ Ground State) Even Z, Even N Fission Product, Slow Neutron Fission of U 235 , U 233 or Pu 239 Isotopic Mass (Carbon-123 Scale)

19.   White or "color" square: ( Artificially Produced Radioactive Nuclide)

20. S 38 2.84 h E 2.94 β - .99,…, γ 1941.9,… Artificially Radioactive Half-Life Beta Disintegration Energy in Mev Modes of Decay with Energy of Radiation in Mev for Alpha and Beta; kev for gammas Symbol, Mass Number

21. Black rectangles across the top of square               a. On gray-shaded square:  Radioactive nuclide with long half life (Considered Stable) b. On white square: Radioactive nuclide found in nature with relatively short half life

22. La 138 5+ Two Isomeric States Both Radioactive Beta Disintegration Energy Followed by Isotopic Mass Spin and Parity Modes of Decay in order of Prominence with Energy of Radiation in Mev for alpha and Beta, Kev for gamma Thermal Neutron Capture Cross Section, followed by Resonance Integral Half-Life Symbol, Mass Number 0.090 1.05 E11 a ϵ , β - .25 γ 1435.8,788.7 σγ ~57,4E2 E 1.04 137.90711 Atom Percent Abundance

23. Smaller black rectangle near top of square          Nuclide is a member of a natural radioactive decay chain

24. Po 218 3.10 m 218.oo8965 α 6.0024 γ 510 β - ω Member of Naturally Radioactive Decay Chain Half-Life Isotopic Mass Modes of Decay and Energy in Mev for Alpha and Beta; kev for gammas ω Indicates Decay Mode Intensity Symbol, Mass Number RaA Historical Symbol

25. Black triangle at bottom corner of square: Refer to item 1 above.          This indicates nuclide is formed by fission of U-235 or Pu-239

26. 6. Vertically divided square Two isomeric states, one stable Two isomeric states, both radioactive

27. Sn 117 1/+ 11/- 13.69 d 7.68 IT 156.0, e- γ 158.6 116.902953 σ γ 1.3, ~ 15 Isotopic Mass Fission Product, Slow Neutron Fission of U 235 , U 233 or Pu 239 Two Isomeric States One Stable Spin and Parity of Ground State, ½+ Spin and Parity of Metastable State, 11/2 - Atom Percent Abundance Modes of Decay with Energy of Radiation in Mev for Alpha and Beta; kev for gammas Thermal Neutron Capture Cross Section in Barns, followed by Resonance Integral in Barns Radioactive Isomer Stable Ground State

28. Co 60 2+ 5+ 10.47 m 5.271 a IT 58.6, e- β - 1.6 ω , γ 1332.5 ω σ γ 60, 2.3E2 β - .318, … γ 1332.5, 1173.2, ….. σ γ 2.0,4 E 2.824 Two Isomeric States Both Radioactive Spin and Parity of Ground State, ½+ Spin and Parity of Metastable State Modes of Decay and Energy in order of Intensity, … Indicates (Where Shown) Range of Energies Included. Thermal Neutron Activation Cross Section in Barns, followed by Resonance Integral in Barns Radioactive m-State Isomer Radioactive Ground State Isomer Half-Life Symbol, Mass Number Beta Disintegration Energy in Mev

29. Other useful information

30. The age of the Earth is 4.54 × 10 9 years ± 1 %

31. Form of Energy Released Amount of Energy Released (MeV) Kinetic energy of two fission fragments 168 Immediate gamma rays 7 Delayed gamma rays 3-12 Fission neutrons 5 Energy of decay products of fission fragments ... Gamma rays 7 Beta particles 8 Neutrons 12 Average total energy released 215 MeV Energy From Uranium Fission

32. Plutonium

33. Mahabad- Iran