3.3.2 Nuclear Energy

3.3.2 NUCLEAR ENERGY

NUCLEAR ENERGY

Electricity Production by Fuel

Electricity Production by Fuel

56%

9%

3%

23%

9% Coal

HydroelectricPowerOther

Nuclear

Natural Gass

U.S. Department of Energy, Annual Energy Review 1999

4

Fig 1: Nuclear Reactors in the World

By the end of 2002: 30 countries

441 reactors 16% of electricity production7% of primary energy

Source : AIEA

• Types• Alpha particles consist of 2 protons and 2 neutrons,

and therefore are positively charged• Beta particles are negatively charged (electrons)• Gamma rays have no mass or charge, but are a form

of electromagnetic radiation (similar to X-rays)• Sources of natural radiation

• Soil• Rocks• Air• Water• Cosmic rays

Radioactivity

www.bio.miami.edu/beck/esc101/Chapter14&15.ppt

http://www.bio.miami.edu/beck/esc101/Chapter14&15.ppt

• Radioactivity: Nuclear changes in which unstable (radioactive) isotopes emit particles & energy

• Radioactive decay continues until the the original isotope is changed into a stable isotope that is not radioactive

Radioactivity



cstl-cst.semo.edu/bornstein/BS105/ Energy%20Use%20-%203.ppt

Relative Doses from Radiation Sources

• Genetic damages: from mutations that alter genes

• Genetic defects can become apparent in the next generation

• Somatic damages: to tissue, such as burns, miscarriages & cancers

Effects of Radiation



www.geology.fau.edu/course_info/fall02/ EVR3019/Nuclear_Waste.ppt

http://www.geology.fau.edu/course_info/fall02/%20EVR3019/Nuclear_Waste.ppt

The time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation to form a different isotope

Half-time emitted Uranium 235 710 million yrs alpha, gammaPlutonium 239 24,000 yrs alpha, gamma

During operation, nuclear power plants produce radioactive wastes, including some that remain dangerous for tens of thousands of years

Half-Life



Destructive power:[1] Small towns have been leveled by floods and landslides.[2] The same size town could be leveled by 1,000 tons of chemical explosives.

[3] Hiroshima (quarter of a million people) was destroyed by releasing the energy in 40 kg of Uranium

We know the least about the strong nuclear force.

Use of Fission Power 1945 first large scale use atomic bombs were

used by the US to knock Japan out of WWIIsince then attention

has been given to the peaceful uses of atomic energy

Nuclear Power Plants

In a conventional nuclear power planta controlled nuclear fission chain reaction

heats waterproduce high-pressure steam that turns turbines generates electricity.



Nuclear Fission approximately 20,000

times as much heat and energy is released from uranium fuels as from an equivalent amount of coal

when a sufficient amount of fissionable material is brought together, a chain reaction occurs splitting atoms and releasing a tremendous amount of heat

Nuclear FissionControlled Fission Chain Reaction

neutrons split the nuclei of atoms such as Uranium or Plutonium

release energy (heat)



Fusion and Fission are governed by the nuclear strong force.

Fusion: two nuclei stick together (or fuse) to form a new, larger nucleus

Two separate nuclei

One new nucleus

Fission: When a single nucleus splits to form two smaller nuclei.

Large nucleus Two smaller nuclei

Controlled Nuclear Fission Reaction

cstl-cst.semo.edu/bornstein/BS105/ Energy%20Use%20-%203.ppt

Conversion of 238U to 239Pu

Under appropriate operating conditions, the neutrons given off by fission reactions can "breed" more fuel, from otherwise non-fissionable isotopes, than they consume



Nuclear Fusion Fusion is combining

together the atoms are fused

together rather than split apart

possibilities for nuclear fusion are much greater than those for nuclear fission

Imagine putting a hydrogen nucleus together instead of pulling it apart. We normally write this in a special way:

n + p

H21

neutronproton Hydroge

n nucleus

This reads: a neutron and a proton fuse together to form a hydrogen nucleus.

+n p

n + p

H21

+n p

More energy Less energy

Where did the excess energy from the left-hand-side go?There must be energy released in this process!! It comes in the form of Radiant and Thermal energy

Nuclear (fusion) Energy

Thermal + Radiant Energy

Fuel for fusion fusion reactors would be

fueled by deuterium, an isotope of hydrogen

available in almost unlimited supply in sea water

FusionProblems: process is so difficult to

control that it is questionable whether commercial adaptation will ever be economically feasible

Fusion Problems fusion requires extreme

pressure and temperatures (as high as 100 million degrees)

such heat was achieved by the Hydrogen bomb by first setting off a fission explosion

Nuclear Energy Concerns

Concerns about the safety, cost, and liability have slowed the growth of the nuclear power industry

Accidents at Chernobyl and Three Mile Island showed that a partial or complete meltdown is possible

Chernobyl•April 26, 1986, reactor explosion (Ukraine) flung radioactive debris into atmosphere

•Health ministry reported 3,576 deaths•Green Peace estimates32,000 deaths;•About 400,000 people were forced to leave their homes

•~160,000 sq km (62,00 sq mi) contaminated•> Half million people exposed to dangerous levels of radioactivity

•Cost of incident > $358 billion



Three Mile Island•March 29, 1979, a reactor near Harrisburg, PA lost coolant water because of mechanical and human errors and suffered a partial meltdown

•50,000 people evacuated & another 50,000 fled area•Unknown amounts of radioactive materials released•Partial cleanup & damages cost $1.2 billion•Released radiation increased cancer rates.



Three Mile Island evacuation of preschool

children and pregnant women within five miles of the plant

What is Going to Happen to Spent Fuel?

Photos from :The Yucca Mountain Project:

http://www.ymp.gov/

1. Low-level radiation (Gives of low amount of radiation)• Sources: nuclear power plants, hospitals &

universities• 1940 – 1970 most was dumped into the ocean• Today deposit into landfills

2. High-level radiation (Gives of large amount of radiation)• Fuel rods from nuclear power plants• Half-time of Plutonium 239 is 24000 years• No agreement about a safe method of storage

Radioactive Waste



Radioactive Waste1. Bury it deep underground.

• Problems: i.e. earthquake, groundwater…2. Shoot it into space or into the sun.

• Problems: costs, accident would affect large area.3. Bury it under the Antarctic ice sheet.

• Problems: long-term stability of ice is not known, global warming

4. Most likely plan for the US• Bury it into Yucca Mountain in desert of Nevada • Cost of over $ 50 billion• 160 miles from Las Vegas• Transportation across the country via train & truck



Yucca Mountain





Conclusion…… “The odds of an American

dying from a nuclear power accident are 300 million to one.”

FissileResources

NuclearReactor

Electricity

Intermediate/LowLevel Waste

Conversion

Enrichment

Uranium Extraction

FuelFabrication

InterimStorage Encapsulation

WasteDisposal

HighLevelWaste

SpentFuel

Long-Term Nuclear Energy Depends on an Advanced

Nuclear Fuel Cycle

ReprocessingRecycle

Recycling TRUIn Adv. Reactor

Fissile Waste235U/233U/239Pu

Electricity& H2

MultipleReactors

FIND A PARTNER, GRAB A BOOK, AND MAKE

A CONCEPT MAP OF:The Nuclear Fuel Cycle

includingHigh level vs. low level

Nuclear Waste

Documents

3.3.2 Nuclear Energy