Nuclear EnergyNuclear Energy

Types of Nuclear Types of Nuclear ReactionsReactions

Fusion: Fusion: Smashing atoms Smashing atoms

togethertogether Makes heavier elementMakes heavier element Not currently cost Not currently cost

effective for large scale effective for large scale productionproduction

Fission:Fission: Energy is released when Energy is released when

nucleus is split apart.nucleus is split apart. 1 g U 1 g U 3 tons coal 3 tons coal

The Fission Chain ReactionThe Fission Chain Reaction

•A neutron hits U-235 nucleus.A neutron hits U-235 nucleus.

•Produces 2 neutrons that hit 2 more Produces 2 neutrons that hit 2 more atoms of U-235.atoms of U-235.

•And so on, and so on…And so on, and so on…

Chain Reaction Chain Reaction SimulationSimulation

•Slowed with control rods &/or waterSlowed with control rods &/or water

Pros:Pros:•No greenhouse gas emissionsNo greenhouse gas emissions

Cons:Cons:•Thermal pollution of local waterways; Thermal pollution of local waterways; can damage local fish & habitatscan damage local fish & habitats•Mining issues. Most U is U-238; <1% Mining issues. Most U is U-238; <1% U-235U-235•Safety concernsSafety concerns

Boiling Water Reactor Boiling Water Reactor (BWR)(BWR)

Pressurized Water Pressurized Water Reactor (PWR)Reactor (PWR)

PWR sim clip

Radioactive DecayRadioactive Decay

Spontaneous disintegration of Spontaneous disintegration of nucleus to lighter and more nucleus to lighter and more stable particlesstable particles

Emit one of 3 possible classes of Emit one of 3 possible classes of decay…decay…

1. Alpha decay1. Alpha decay

Alpha Particle He nucleus (2pAlpha Particle He nucleus (2p++, 2n, 2n00)) External effect—minimum. Easily stopped.External effect—minimum. Easily stopped. Internal effect—carcinogenicInternal effect—carcinogenic Common Source: natural radon, americium-241Common Source: natural radon, americium-241

2. Beta Decay2. Beta Decay

Electron emitted. Electron emitted. Tritium, Carbon-14, medical usesTritium, Carbon-14, medical uses Carcinogenic, can burn skin. Carcinogenic, can burn skin.

Usually chronic exposure, not acuteUsually chronic exposure, not acute

3. Gamma Radiation3. Gamma Radiation

Radium-226, cesuim-137Radium-226, cesuim-137

Can travel through body, hit all organsCan travel through body, hit all organs

Acute Radiation Sickness: vomiting, Acute Radiation Sickness: vomiting, burns, kills blood cells, hair loss, deathburns, kills blood cells, hair loss, death

Other Effects of Gamma Radiation

Decay and Half-LifeDecay and Half-Life

Half-Life: Half-Life:

Time needed for ½ of atoms to decayTime needed for ½ of atoms to decay Co-60 10.47 minutesCo-60 10.47 minutes P-32 14.28 daysP-32 14.28 days C-14 5715 yearsC-14 5715 years U-238 4.46 x 10U-238 4.46 x 1099 years years

Nuclear Waste DisposalNuclear Waste Disposal Byproducts U-234, U-237, Np-237, Byproducts U-234, U-237, Np-237,

Pu-238 and Am-241, all radioactivePu-238 and Am-241, all radioactive

Wet Storage: on site water tanksWet Storage: on site water tanks

Dry Storage: onsite lead & steel Dry Storage: onsite lead & steel caskscasks

Underground Storage: Centralized. Underground Storage: Centralized. Yucca Mt, NV proposal out of the Yucca Mt, NV proposal out of the 2010-11 US budget2010-11 US budget

Breeder ReactorsBreeder Reactors

Convert U-238 into Pu-239, also Convert U-238 into Pu-239, also fissilefissile

Use liquid Na as coolant instead of Use liquid Na as coolant instead of waterwater

Pu used as weapons materialPu used as weapons material

Infamous AccidentsInfamous Accidents Three Mile Island, Pa 1979Three Mile Island, Pa 1979

Pump malfunctioned in 2Pump malfunctioned in 2oo system system Caused Pressure in reactor to rise & Caused Pressure in reactor to rise &

vent. vent. Vent got stuck open Vent got stuck open core temps rose, core temps rose, partial meltdown occurredpartial meltdown occurred No significant release of radiationNo significant release of radiation

Unit 1

Chernobyl, Ukraine 1986Chernobyl, Ukraine 1986 Power surge during a test. Power surge during a test. Emergency shutdown attempt caused spike in Emergency shutdown attempt caused spike in

power output. power output. Reactor vessel ruptured and a series of steam Reactor vessel ruptured and a series of steam

explosionsexplosions Graphite moderator caught fire when exposed Graphite moderator caught fire when exposed

to air.to air. Plumes of smoke sent over regionPlumes of smoke sent over region Officially 2 plant workers, 29 emergency Officially 2 plant workers, 29 emergency

workers died as a result, most from acute workers died as a result, most from acute radiation sicknessradiation sickness

Detected in Sweden a few days after explosionDetected in Sweden a few days after explosion

Fukushima, Japan 2011Fukushima, Japan 2011 Reactors automatically shut down Reactors automatically shut down

following earthquake & tsunamifollowing earthquake & tsunami Emergency generators came on to keep Emergency generators came on to keep

coolant flowing, but were flooded by coolant flowing, but were flooded by seawaterseawater

Coolant levels dropped, reactor cores Coolant levels dropped, reactor cores overheated & melted downoverheated & melted down

HH22 buildup in reactors caused explosions buildup in reactors caused explosions into containment buildingsinto containment buildings

No reported radiation deaths; risks of No reported radiation deaths; risks of cancer uncertaincancer uncertain

Salem I & II (PWR) & Hope Salem I & II (PWR) & Hope Creek (BWR)Creek (BWR)

Oyster Creek (BWR)Oyster Creek (BWR)

How is Electricity Consumed in US How is Electricity Consumed in US homeshomes