Nuclear Fission and Fusion

What is fission?One nucleus splits into two smaller nuclei and typically a few neutrons by the bombardment of a neutron. U-235 is the only naturally occurring nuclide that fissionsHowever, both U-238 and Th-232 can be converted into into fissile isotopes: Pu-239 and U-233.Found in: atomic bombs, Hydrogen bomb, and nuclear power plantsFission is DIVISION

Watch this!One gram of U-235 can release enough energy during fission to raise the temperature of 66 million gallons of water from 25oC to 100oC!

This pool115 ft. deep3/5 mi. wide

Nuclear power reactors are designed to use the controlled fission through chain reactions.

What else can fission do?Fission is the culprit of the atomic bomb.Fission creates waste that has half-lives of several hundred years.

How is fission controlled?Neutron moderation –

Slows down the neutrons so they can be captured by the reaction fuel to continue the chain reactionUses H2O and C

Neutron absorption –Decreases the # of neutrons

Control rods –Uses neutron absorptionExtends into the reactor core & absorbs neutrons

Nuclear Power Plants

Nuclear Waste

Fuel rods are a major source of nuclear wasteWhen there is no longer enough fuel, they need to be removed from the reactor

Water is used to keep these spent rods cool and acts as a radiation shield to reduce the levels being released into the atmosphere

May stay in these holding tanks for 0 or more years

Can nuclear reactors lead to a nuclear explosion?

No!!!Fuel elements are too separate and can’t combine to reach supercritical massOnly can have a meltdown of the nuclear core, which will melt the lead encasement and cause a possible steam explosion with the radiation

The A-Bomb In 1939, The Nazis were rumored to developing an atomic bomb. President Roosevelt wanted to make sure that the United States did not fall behind and he created the team known as the Manhattan Project.The Manhattan Project was a group of scientists who created the first atomic bomb.General Leslie R. Groves, Deputy Chief of Construction of the U.S. Army Corps of Engineers, was appointed to direct this top-secret project.

What is special about this bomb?Italian physicist Enrico Fermi managed the University of Chicago reactor, called Chicago Pile 1 (CP-1). On the afternoon of December 2, 1942, the first controlled nuclear fission reaction occurred.

J. Robert Oppenheimer (1904-1967)

In November 1942, Oppenheimer chose the site where the first atomic bombs were designed and built. The site at Los Alamos, N.M.

                           

The first oneOn July 16, 1945, the world entered the nuclear age with the detonation of the first atomic bomb. The first bomb was known as "Gadget"

"Little Boy" - The Uranium Bomb

Explode above the ground of Hiroshima.

"Fat Man" - The Plutonium Bomb

Explode above the ground but caused an implosion on Nagasaki.

What is fusion?A nuclear reaction in which two small nuclei combine (or fuse) to form one massive nucleus.

Takes place at 40 million degrees Celsius!Occurs on the SUN, STARS, and also in the HYDROGEN BOMB.

Produces LOTS more energy than fission

Watch this!Fusion reactions

1 lb. of fuel can release about 1,000,000x’s more energy than 1 lb. of coal.

Very little radioactive waste!Materials are cheap and readily available.

The Hydrogen BombAlso called a thermonuclear bomb.Goal of the government is to make this a useful weapon by the year 2015.Helium is the only waste product.Uses fission bombs to reach the high temperatures to start a fusion reaction

First Fusion Bomb Test (1952)This test was conducted on an island. After the bomb went off, the entire island was gone. Called “Ivy Mike”1,000 x stronger than an atomic bomb

So what about this cold fusion mumbo jumbo?

The idea of cold fusion is to create the same power of fusion but at room temperature. Almost impossible according to nuclear theory.1989, Stanley Pons & Martin Fleischman ‘claimed’ this feat of science.