Where is the Energy coming from? - ISNAP

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Where is the Energy coming from? - ISNAP

Energy

and

Society


OECD countries

The mission of the Organiza1on for Economic Co-­‐opera1on

and Development (OECD) is to promote policies that will

improve the economic and social well-­‐being of people around

the world.

Assignment for Tuesday Oct. 2, 2012!


Country

Date

AUSTRALIA 7 June 1971

AUSTRIA 29 September 1961

BELGIUM 13 September 1961

CANADA 10 April 1961

CHILE 7 May 2010

CZECH REPUBLIC 21 December 1995

DENMARK 30 May 1961

ESTONIA 9 December 2010

FINLAND 28 January 1969

FRANCE 7 August 1961

GERMANY 27 September 1961

GREECE 27 September 1961

HUNGARY 7 May 1996

ICELAND 5 June 1961

IRELAND 17 August 1961

ISRAEL 7 September 2010

ITALY 29 March 1962

JAPAN 28 April 1964

KOREA 12 December 1996

LUXEMBOURG 7 December 1961

MEXICO 18 May 1994

NETHERLANDS 13 November 1961

NEW ZEALAND 29 May 1973

NORWAY 4 July 1961

POLAND 22 November 1996

PORTUGAL 4 August 1961

SLOVAK REPUBLIC 14 December 2000

SLOVENIA 21 July 2010

SPAIN 3 August 1961

SWEDEN 28 September 1961

SWITZERLAND 28 September 1961

TURKEY 2 August 1961

UNITED KINGDOM 2 May 1961

UNITED STATES 12 April 1961


What about Elements?

Greeks

460-­‐370 BCE

Boyle (1600’s)

elements as fundamental substances that

cannot be broken down further by chemical

means.


1869

Atomic Number ?

Atomic Weight ?


The Chart of Nuclides

Atomic Number ? Z or the number of protons

Atomic Weight ? Z+ N= A + number of protons + number of neutrons


Signatures of Nucleosynthesis

B 2 FH

=Z+ N


Nuclei are made in Stars

1me


Elemental Abundances

Human Body

Oxygen 65

Carbon 18

Hydrogen 10

Nitrogen 3

Calcium 1.5

Phosphorus 1.2

Potassium 0.2

Sulfur 0.2

Chlorine 0.2

Sodium 0.1

Magnesium 0.05

Universe

Iron, Cobalt, Copper, Zinc,Iodine


Explosion of a star that died 13 Billion years ago

Ar1st: Nicolle Roger Fuller (NSF)


Each heavy atom in our body

was processed through ~40

supernova explosions since the

beginning of time!

We are made of star stuff….

Carl Sagan


Where is the Energy coming from??????

Splitting the Uranium Atom:

Uranium is the principle element used in nuclear reactors

and in certain types of atomic bombs. The specific isotope

used is 235 U. When a stray neutron strikes a 235 U nucleus,

it is at first absorbed into it. This creates 236 U. 236 U is

unstable and this causes the atom to fission.

• 235 U + 1 neutron

• 235 U + 1 neutron

2 neutrons + 92 Kr + 142 Ba + ENERGY

2 neutrons + 92 Sr + 140 Xe + ENERGY


Binding Energy Curve:

Energy can be released from fusion and fission!


Nuclear binding energy = Δmc 2

For the alpha particle Δm= 0.0304 u which gives a binding

energy of 28.3 MeV.


The enormity of the nuclear binding energy can perhaps be better

appreciated by comparing it to the binding energy of an electron in an atom.

The comparison of the alpha particle binding energy with the binding energy

of the electron in a hydrogen atom is shown below. The nuclear binding

energies are on the order of a million times greater than the electron

binding energies of atoms.


Radioactivity

Americium -­‐241: Used in many smoke detectors for homes and business...

Cadmium -­‐109: Used to analyze metal alloys for checking stock, sor1ng scrap.

Calcium -­‐ 47: Important aid to biomedical researchers studying the cell func1on and

bone forma1on of mammals.

Californium -­‐ 252: Used to inspect airline luggage for hidden explosives...to gauge the

moisture content of soil in the road construc1on and building industries...and to measure

the moisture of materials stored in silos.

Carbon -­‐ 14: Helps in research to ensure that poten1al new drugs are metabolized without

forming harmful by-­‐products.

Cesium -­‐ 137: Used to treat cancers...

Chromium -­‐ 51: Used in research in red blood cell survival studies.

Cobalt -­‐ 57: Used in nuclear medicine to help physicians interpret diagnosis scans of

pa1ents' organs, and to diagnose pernicious anemia.

Cobalt -­‐ 60 : Used to sterilize surgical instruments...spices/fruits

Copper -­‐ 67: cancer


Radioactivity

Alpha decay

Beta decay

Electron capture

Gamma Decay

Half-life

very short

very long- longer than age of earth….billions of yrs

14

C 5730 yrs


Alpha Decay


Beta Decay


Gamma Decay


Half-lives are very often used to describe quantities undergoing

exponential decay—for example radioactive decay—where the half-life is

constant over the whole life of the decay.

Number of

half-­‐lives

elapsed

Frac1on

remaining

0 1

/ 1 100

1 1

/ 2 50

2 1

/ 4 25

Percentage

remaining

3 1

/ 8 12 .5

4 1

/ 16 6 .25

5 1

/ 32 3 .125

6 1

/ 64 1 .563

7 1

/ 128 0 .781

... ... ...

n 1/2 n 100(1/2 n )


A quantity is said to be subject to exponential decay

if it decreases at a rate proportional to its value. Symbolically,

this can be expressed as the following differential equation,

where N is the quantity and λ is a positive number called the

decay constant.

The solution to this equation is:

Here N(t) is the quantity at time t, and N 0

= N(0) is the initial

quantity, i.e. the quantity at time t = 0.


.

Half-­‐life:1me required for the decaying quan1ty to fall to one half of its ini1al

value

This 1me is called the half-­‐life, and ojen denoted by the symbol t 1 / 2

.

The half-­‐life can be wriken in terms of the decay constant, or the mean life1me,

as:

Example: 14 C…..0.693/5730 yrs =1.21 x10 -­‐4 /yr

or λ=ln2/t 1/2

Example: How old is an object whose 14C content is 10% of what it is in living

organisms today?


Environmental and safety aspects of nuclear energy

Not in My Back Yucca

What are our alternatives for storing

radioactive waste?

By Brendan I. Koerner

Posted Tuesday, April 15, 2008, at 8:11 AM ET

Environmental Statement on Nuclear

Energy and Global Warming

June 2005

Too expensive – power plants…

Too dangerous-­‐ terrorist groups

Too pollu1ng-­‐ radioac1ve waste


Thorium: Is It the Better Nuclear Fuel?

What is special about thorium?

(1) Weapons-grade fissionable material (uranium 233 ) is harder to retrieve safely

and clandestinely from the thorium reactor than plutonium is from the uranium

eeder reactor.

(2) Thorium produces 10 to 10,000 times less long-lived radioactive waste than

uranium or plutonium reactors.

(3) Thorium comes out of the ground as a 100% pure, usable isotope, which does

not require enrichment, whereas natural uranium contains only 0.7% fissionable

235

.

(4) Because thorium does not sustain chain reaction, fission stops by default if

we stop priming it, and a runaway chain reaction accident is improbable.


Here is the thorium sequence in the Rubbia reactor: A neutron is captured by

90 Th232 , which makes it 90 Th 233 .

90 Th232 + 0 n1 -> 90 Th233 [1]

Thorium-233 spontaneously emits a beta particle (an electron from the nucleus, see

p 173), leaving behind one additional proton, and one fewer neutron. ("...Nuclear

Energy" p134) This is called "beta decay."

90 Th233 -> 91 Pa233 + ß [2]

The element with 91 protons is Protactinium (Pa). The isotope 91 PA 233 also

undergoes beta decay,

91 Pa233 -> 92 U233 + ß [3]

The U 233 isotope that is produced in step [3] is fissionable, but has fewer neutrons

than its heavier cousin, Uranium-235, and its fission releases only 2 neutrons, not 3.

92 U233 + 0 n1 -> fission fragments + 2 0 n 1 [4]


Fusion Energy (how the sun gets its energy)

In a fusion reaction, two light atomic nuclei fuse together to form

heavier ones, as is shown in the figure. The fusion process releases a

large amount of energy, which is the energy source of the sun and the

stars.

Proton + neutron=deuterium

Proton + 2 neutrons=tritium


D+ T= 4 He +n + 17.6 MeV

2

H+ 3 H= 4 He


Fusion energy


Fusion Inside the Stars

• Fusion in the core of stars is reached when

the density and temperature are high

enough. There are different fusion cycles

that occur in different phases of the life

of a star. These different cycles make the

different elements we know. The first

fusion cycle is the fusion of hydrogen into

Helium. This is the stage that our Sun is in.


The long-term objective of

fusion research is to harness

the nuclear energy provided

by the fusion of light atoms to

help meet mankind´s future

energy needs.


How do we get energy from fossil fuels?

Nuclear fuels?

One example….

ThinkQuest


A water turbine is a

rotary engine that

takes energy from

moving water.


Boiling Water Reactor

In the boiling water reactor the same water loop serves as moderator, coolant for the core,

and steam source for the turbine.

Boiling Water Reactor

In the boiling water reactor (BWR), the water which passes over the reactor core to act as moderator and

coolant is also the steam source for the turbine. The disadvantage of this is that any fuel leak might make the

water radioac1ve and that radioac1vity would reach the turbine and the rest of the loop.

A typical opera1ng pressure for such reactors is about 70 atm at which pressure the water boils at about 285

C. This opera1ng temperature gives a Carnot efficiency of only 42% with a prac1cal opera1ng efficiency of

around 32%, somewhat less than the pressure water reactor.


Pressurized Water Reactor

In the pressurized water reactor, the water which flows through the

reactor core is isolated from the turbine.

In the pressurized water reactor (PWR), the water which passes over the reactor core

to act as moderator and coolant does not flow to the turbine, but is contained in a

pressurized primary loop. The primary loop water produces steam in the secondary loop

which drives the turbine. The obvious advantage to this is that a fuel leak in the core

would not pass any radioactive contaminants to the turbine and condenser.

Another advantage is that the PWR can operate at higher pressure and temperature,

about 160 atm and about 315 C. This provides a higher Carnot efficiency than the

BWR, but the reactor is more complicated and more costly to construct. Most of the

U.S. reactors are pressurized water reactors.

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