1. Section 3: Fission and Fusion

2. Fission
Fission is the splitting of an atomic nucleus into two smaller parts.
In nuclear fission, tremendous amounts of energy can be produced from very small amounts of mass.
E = mc2

3. Fission
The fission of uranium-235 yields smaller nuclei, neutrons, and energy.
Neutron

4. Fission
The fission of uranium-235 yields smaller nuclei, neutrons, and energy.
Neutron

5. Fission
The fission of uranium-235 yields smaller nuclei, neutrons, and energy.
Neutron

6. Fission
The fission of uranium-235 yields smaller nuclei, neutrons, and energy.
Neutron
Energy

7. Triggering a Chain Reaction
Fission
Triggering a Chain Reaction
In a chain reaction, neutrons released during the splitting of an initial nucleus trigger a series of nuclear fissions.

8. Nuclear Fission of Uranium-235

9. Fission

10. Fission
In an uncontrolled chain reaction, all of the released neutrons are free to cause other fissions.
The result is a fast, intense release of energy.
Nuclear weapons are designed to produce uncontrolled chain reactions.

11. Fission
In a controlled chain reaction, some of the neutrons are absorbed by other materials.
The heat from controlled chain reactions can be used to generate electrical energy, which doesn’t emit pollutants.

12. Nuclear Power Plant

13. Fission
Unfortunately, a product of controlled chain reactions is radioactive waste.
A crane lowers drums of radioactive waste into a landfill in Hanford, Washington.

15. Fusion
Fusion is a process in which the nuclei of two atoms combine to form a larger nucleus.
A small fraction of the reactant mass is converted into energy.
Fusion produces more energy than fission!!

16. Fusion

17. Fusion
The sun and other stars are powered by the fusion of hydrogen into helium.
requires extremely high temperatures (10 to 100 million oC).
Hydrogen must be in the plasma state (difficult to contain)

18. Fusion
The Tokamak Fusion Test Reactor at the Princeton Plasma Physics Laboratory was one of the very few fusion reactors that have been built.

19. Fission vs Fusion Fission Fusion vs. FISSION FUSION 235U is limited
meltdown risk
radioactive waste
less energy
Hydrogen is abundant
no meltdown risk
harmless product
not yet sustainable

20. Which of the following statements about nuclear fission is false?
Assessment Questions
Which of the following statements about nuclear fission is false?
Fission is the splitting of a nucleus into two smaller parts.
Fission produces tremendous amounts of energy from a small mass.
Mass is conserved during nuclear fission.
Fission does not always yield the same products.

21. Which of the following statements about nuclear fission is false?
Assessment Questions
Which of the following statements about nuclear fission is false?
Fission is the splitting of a nucleus into two smaller parts.
Fission produces tremendous amounts of energy from a small mass.
Mass is conserved during nuclear fission.
Fission does not always yield the same products. ANS: C

22. Assessment Questions
Why has nuclear fusion not been used to produce power on Earth.
Fusion only occurs in high temperature plasmas, which cannot yet be controlled.
Nuclear fusion requires deuterium, which is not available on Earth.
Fusion does not produce enough energy to justify its use.
Scientists do not yet know how to start a fusion reaction.

23. Assessment Questions
Why has nuclear fusion not been used to produce power on Earth.
Fusion only occurs in high temperature plasmas, which cannot yet be controlled.
Nuclear fusion requires deuterium, which is not available on Earth.
Fusion does not produce enough energy to justify its use.
Scientists do not yet know how to start a fusion reaction. ANS: A