Nuclear Fusion

Energy

Fusion – perfect, but difficultsmall nuclei combine to create larger atoms

2H + 3

H 4He + 1

n +

1 1 2 0

Occurs in the sun and other stars

Nuclear Fusion• “Hot” fusion -- difficult to contain 100million Kelvins• At this temperature a Plasma is formed (charged ions as a gas)• Nuclear Physicists use Magnets to contain the hot plasma and force

the plasma together

Nuclear Fission

•Nuclear fission can be induced by bombarding atoms with neutrons.

•Induced fission decays are also accompanied by the release of neutrons and LOTS of energy

•The nuclei of the atoms then split into 2 parts.

Each time a fission occurs, large amounts of energy are released

Under certain conditionsa chain reaction is startedthat creates a HUGE amount of energy to be released very quickly!

• When this source of energy was discovered in the last century, it was first used as a massive weapon.

Fission Bombs

• Called “atomic bombs” or “A-bombs”

• Critical mass = need enough U-235 to start an uncontrollable fissioning chain reaction!

• Strength of up to 500,000 TONS of TNT

Little Boy dropped on Hiroshima: August 6, 1945

• Uranium bomb• Gun-type assembly (15

kTons)

Fat Man dropped on Nagasaki: August 9, 1945

• Plutonium made at Hanford in Washington State

• Implosion bomb (21 kTons)

Fusion Bombs

• “H-bombs” or Thermonuclear Bombs

• Developed after WWII• Mixture of Fission and

Fusion– Fission first to get energy up– Then fusion started– Then more fission once

reaction gets going!

• They have found a way to tap the energy in nuclear reactions in a controlled way.

http://www.msnbc.msn.com/id/42029294/ns/technology_and_science-science/t/how-nuclear-plant-works/

Link to Animation

Infamous Powerplant 3 Mile Island

March 1979 Pennsylvania Core meltdown in

reactor: human error and valve issue

Most significant nuclear accident in US history

1-2 cancer deaths due to accident

Infamous Powerplant CHERNOBYL

April 1986UkraineReactor vessel rupture

and explosions atmosphere

32 immediate deaths; 100,000s of cancer-related deaths since

19 mile evacuation zone still in place today

Infamous Powerplant FUKUSHIMA

March 2011JapanEarthquake and tsunami

knocked out central power and generator power, so the reactions couldn’t be controlled

37 with physical injuries, 2 workers hospitalized and 1 death (from a heart attack)

Nuclear Fission & POWER• Currently about 103 nuclear power

plants in the U.S. and about 434

worldwide.

• 17% of the world’s energy comes

from nuclear.

Anything Else?

What questions do you still have that I can answer next time?

HomeworkReading on Nuclear Powerplants

Answer the questions at the end