First, what is a Nuclear Reaction ?
Remember that the nucleus of every atom is composed of protons ( p+ ) and neutrons ( no ). If you add or subtract a nucleon to a nucleus, this is a nuclear reaction.
- Gravity is the force that prevents the Sun from expanding despite the fact that it is a hot gas. Gravity also keeps the Earth forever falling towards the Sun in its orbit and keeps all the people in this room in their seats. One way to look at gravity is that it is an attractive force between objects with mass.
- Electric Force is a force felt between charged particles like electrons (e-) and protons (p+). There are both attractive and repulsive electrical forces. Like charges repel, opposite charges attract. The Electrical Force holds atoms and molecules together and is useful for all kinds of nifty gadgets that have been built in the last 150 years.
Fun note: The electric force is what keeps you from falling through the chair and floor and earth and being cooked in the center of the Earth. You are suspended above your chair by the repulsive force of the protons in your body against the protons in the chair.
- Nuclear Force. If you think about it for a minute, the nuclei of atoms which contain protons (positively charged) and neutrons (no charge) should not be stable. All those "like" charged protons should be repelling one another and fly right out of the nucleus. Since nuclei ARE stable, it can be inferred that there is another force that is stronger than the electrical force which glues those nuclei together. This is the Nuclear Force, or Strong Force. The nuclear force would bind EVERYTHING together except for the fact that it acts only over very tiny distances.
For the "heavy" elements in the Periodic Table, there are some that have nuclei that spontaneously fall apart - these are the radioactive elements. The wild thing about this is that if you weigh the initial nucleus and weigh the bits after the "fission", they don't add to the same total.
This equation says that Mass and Energy are interchangable.
Take the mass difference between the Uranium nucleus and the sum of the Thorium and Helium nuclei, multiply by the speed of light squared and you have the amount of energy that was converted from mass in the reaction (released in the form of gamma rays).
where m is the mass difference between the Uranium nucleus and the fission product nuclei.
The shorthand for this reaction is:
|Step I:  ||1H1 + 1H1     2H1 + e+ + o|
|Step II:  ||1H1 + 1H1     3He2 +|
|Step III:  ||3He2 + 3He2     4He2 + 1H1 + 1H1 +|
The whole thing can be summarized with one net reaction:
4He2 + 2
o + Energy (
Here is the amazing thing:
|Mass (4H)||  =  ||6.6943 x 10-24 grams|
|Mass (4He2 + 2 o)||  =  ||6.6466 x 10-24 grams|
So, 0.048 x 10-24 grams of matter disappear in the P-P chain.
This mass has been converted into energy (gamma rays). For one reaction, the energy released is:
|E||  =  ||0.048 x 10-24||grams x c2|
|  =  ||4.3 x 10-5||ergs|
For every 4 hydrogen atoms (6.7 x 10-24 grams) we get this much energy out of the reaction, so we can calculate the efficiency of the P-P chain, and compare it to the efficiency of coal power and gravitational potential energy:
|6.4 x 1018||ergs/gram||  from P-P Chain|
|1 x 1015||ergs/gram||  from GPE conversion|
|4 x 1012||ergs/gram||  from chemical burning|
The available energy from hydrogen fusion is:
(6.4 x 1018 ergs/grams)   x   (2 x 1033 grams)   =   12.8 x 51 ergs
The lifetime of the Sun with fusion power would be:
12.8 x 1051 ergs   x   1 sec
=   3.2 x 1018 seconds 4 x 1033 ergs
= 1011 years
Looks pretty promising!
It's for real - don't forget Bikini Atoll which was the nuclear proving ground for the atom bomb.