Nuclear Fission and Fusion

TEKS Par 112.35 #12c

Discovery of Fission

James Chadwick discovered the neutral particle in the nucleus of the atom in 1932.

He called it a “neutron.” Many scientists then started experimenting with

neutrons. Enrico Fermi and his team bombarded every

known element with neutrons, and found among the products some new, radioactive elements.

Neutrons had caused fission, or breakup, of nuclei

Fission of Uranium

Uranium produced lighter but radioactive products when bombarded with neutrons.

Fermi discovered that neutrons could be slowed down by first funneling them through light elements like carbon.

Ida Noddack, Otto Hahn and Lise Meitner showed that uranium was fissioning into barium and other lighter, radioactive elements.

Later, U-235 and Pu-239 were shown to be the best candidates for fission with slow neutrons.

Fission Reaction

U-235 fissions like this:

Visionlearning.com

Nuclearenergyissafe.com

The products of fission are unpredictable and radioactive

Nuclear Energy

Because matter is converted into energy in nuclear reactions, fission produces a great deal of heat

When controlled, this can be used to drive turbines that produce electricity, as in the South Texas Nuclear Project.

Window.state.tx.us

Nuclear Energy

Because matter is converted into energy in nuclear reactions, fission produces a great deal of heat

When released from a carefully engineered nuclear weapon, this energy can do an incredible amount of damage, as when the U.S. dropped bombs on Japan to end WW2.

Nuclear-news.net

Nuclear Fission

Nuclear fission occurs when two light elements are forced together to make a heavier one.

The two nuclei FUSE into a new one. This releases a great deal of energy. Here is a typical reaction equation:

H-3 + H-2 → He-4 + n + energy

Uses of Fusion

Nuclear fusion occurs in the sun and other stars, and so it gives us all the energy used on earth in photosynthesis.

Gosunstove.com

So if your house has solar cells, fusion is the ultimate source of the electricity.

Uses of Fusion

Nuclear fusion is the driving force behind thermonuclear weapons.

They are no longer tested in the atmosphere. They had released much harmful radioactive isotopes in the 1950s.

en.wikipedia.org

Electricity from fusion?

Nuclear fusion would use a cheap fuel—hydrogen from water.

It would generate less nuclear waste. Research into fusion reactors has been going on

since the 1940s. There is no working fusion reactor yet.

Summary

Nuclear Reactions

Type WhatHappens

By-products

EnergyUses

WasteProblems?

Fission U-235 or Pu-239 splits

Radio-active

isotopes

ElectricPower/

weapons

Where to store the

radioactive waste?

Terrorism.

Fusion H nuclei forced

together

NeutronsSmall

elements

Sun & stars/

weapons

If weapons are used,

uncontrolled radiowaste