How does nuclear reactor work. 7:30 min

http://www.youtube.com/watch?v=LTnfXLws40Q

Fukushima 3 minhttp://www.youtube.com/watch?v=BdbitRlbLDc

http://www.youtube.com/watch?v=f2aXsZDWRUA

Fukushima Now 14 min

Energy from Fission & Fusion

Binding E per Nucleon.

Fission – liberates E.

Can use particles (no) to induce fission.

Typical

235U + 1n 236 U 90Sr + 144Xe +2 1n +E. 92 0 92 38 54 0.

The ejected neutrons can split more U-235.

Fission can be self sustaining. It will continue until all the U-235 used up.

For bombs, we don’t bother to control the no produced. We want a runaway chain rx.

In power plants, we do control the reaction to block the neutrons using control rods.

Control Rods control rx rate by blocking or absorbing some of no formed in rx.

Nuclear Power Plant – induces fission in Uranium.

U – 235 bombarded with neutrons. Fission is started. U splits into parts and emits more neutrons. These released no start chain reaction.

Nuclear Power

Makes use of artificial transmutation to get fission process going. Uranium is bombarded with neutrons.

Moderators are used to slow the neutrons. Nuclei need slower no or they cannot absorb.

Critical Mass is the minimum amount of U-235 to get fission process going.

Nuclear Fusion

• 2 light nuclei combine forming heavier ones.

• H combines to form He.

• Process that fuels the sun and other stars.

Fusion Deuterium & Tritium

Typical Hydrogen Fusion Rx 3 parts.

H-1 + H-1 fuses to H-2 +E.H-1 + H-2 fuse to He-3 + EHe-3 + He-3 fuse to He-4 + H-1 + E. Liberates tons of energy.

Problems:

• Need high KE to smash nuclei

• Need to contain very high temperatures and pressures.

• Energy released would cause matter to ionize and go into plasma state.

Bainbridge Mass Spectrometer

• Used to find mass of different nuclei.

• Verifies that isotopes exist.

• Uses electric and magnetic fields to accelerate and deflect nuclei.

Mass spec begins with source (usu. Heating) to strip nuclei of e- which get accelerated through p.d. The velocity is controlled by crossed electric and magnetic fields which balanced forces.

Ion source

X X X X X X

- - - - - - -

++++++

++++++Velocity Felc = F mag.Control

Eq = qvB

v = E B

p.d.

e- will fly straight Fnet =0

The beam enters a vacuum with a magnetic field & is deflected into a curved path.

X X X X X X

- - - - - - -

++++++

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Fc = Fmag.

mv2 = qvB r

mv= qBr

Radius of curvature is proportional to mass.Large masses don’t curve as much.

detectors.