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
B2FH
=Z+ N
Nuclei are made in Stars
1me Elemental Abundances Human Body
Universe
Hydrogen
Helium
Oxygen
Carbon
Neon
Iron
Nitrogen
Silicon
Magnesium
Sulfur
All Others
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
Iron, Cobalt, Copper, Zinc,Iodine<0.05 each
Selenium, Fluorine
<0.01 each
74
24
1.07
0.46
0.13
0.11
0.095
0.065
0.058
0.044
0.065
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 235U. When a stray neutron strikes a 235U nucleus,
it is at first absorbed into it. This creates 236U. 236U is
unstable and this causes the atom to fission.
• 235U + 1 neutron
• 235U + 1 neutron
2 neutrons + 92Kr + 142Ba + ENERGY
2 neutrons + 92Sr + 140Xe + ENERGY
Binding Energy Curve:
Energy can be released from fusion and fission!
Nuclear binding energy = Δmc2
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
14C
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 Percentage remaining 0 1/
1 100 1 1/
2 50 2 1/
4 25 3 1/
8 12 .5 4 1/
16 6 .25 5 1/
32 3 .125 6 1/
64 1 .563 128 0 .781 7 1/
... ... ... n 1/2n 100(1/2n) 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 N0 = 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 t1 / 2. The half-­‐life can be wriken in terms of the decay constant, or the mean life1me, as: 1/2 Example: 14C…..0.693/5730 yrs =1.21 x10-­‐4 /yr Example: How old is an object whose 14C content is 10% of what it is in living organisms today? or λ=ln2/t 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 (uranium233) is harder to retrieve safely
and clandestinely from the thorium reactor than plutonium is from the uranium
reeder 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
U235.
(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
232, which makes it
233.
90Th
90Th
90Th232 + 0n1 -> 90Th233 [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."
90Th233 -> 91Pa233 + ß [2]
The element with 91 protons is Protactinium (Pa). The isotope 91PA233 also
undergoes beta decay,
91Pa233 -> 92U233 + ß [3]
The U233 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.
92U233 + 0n1 -> fission fragments + 20n1 [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= 4He +n + 17.6 MeV
2H+ 3H=4He
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.