We will denote any isotope by using the notation

1
Atomic and Nuclear Structure
We will denote any isotope by using the notation
A X Z where X is the
elements chemical symbol (e.g. H for Hydrogen,
He for Helium etc.), Z is the atomic number (the
number of protons in the nucleus) and A is the
mass number (the number of neutrons and protons
in the nucleus). If we denote the number of
neutrons in the nucleus by N, then we have A Z
N For example 235
U 92 is the isotope Uranium-235 with a
nucleus consisting of 92 protons and 235 92
143 neutrons. 1 H 1 Is a
proton, the nucleus of the isotope Hydrogen-1,
whereas Hydrogen-2 is the nucleus of the isotope
Deuterium (heavy hydrogen) which consists of a
proton and a neutron bound together.
2
The Mass Defect and Nuclear Binding Energy
The sum of the masses of the individual masses
of the protons, neutrons and electrons, gives the
total constituent mass of an atom. The rest
masses of these three fundamental particles
are Rest mass of electron me 0.0005486 u Rest
mass of proton mp 1.007276 u Rest mass of
neutron mn 1.008665 u where u is the atomic
mass unit 1.660539x10-27 kg If one compares
this with the total mass of the actual atom (with
the bound nucleus) one discovers that the latter
is smaller, and the difference is the so-called
nuclear mass defect mdefect. Einstein (1905)
made the celebrated proposal (since substantiated
by experiment) that this mass defect is
equivalent to energy, namely the binding energy
of the nucleus, so that EB mdefectc2 where c
is the speed of light (3x108 ms-1). Because
energy conversions are required in this sort of
topic, we can express c2 in energy/mass units
namely 931 MeV/u, where 1 eV 1.602 x10-19 J.
3
(No Transcript)
4
(No Transcript)
5
D2 T3 ? He4 n1 17.6 MeV
by an Australian, Sir Mark Oliphant (and Lord
Rutherford), 1932
Why D-T? It has the lowest energy barrier of all
fusion reactions
6
Nuclear Processes in the Sun
1 4 0 0 0 4 H
? He 2 e 3 ? 2 ? Q 24.8 MeV 1
2 1 0 0 which is
actually made up of the following steps
1 1 2 0 0 Step 1
H H ? H e ? Q 0.4 MeV 1 1
1 1 0 2 1 3
0 Step 2 H H ? He ? Q 5.5
MeV 1 1 2 0 Note that
step 2 must occur twice before step 3 can take
place 3 3 4 1
0 Step 3 He He ? He 2H ? Q 13.0
Me V 2 2 2 1 0
For the overall balance, steps 1 and 2 occur
twice giving the energy release of 2x(0.4 5.5)
13 MeV 24.8 MeV. Actually there is an
alternative step 3 but the information above
gives an indication
7
Fusion Reactions 1/2
Each reaction is characterised by its energy
release and its rate. Total energy release
(MeV) 2D 2D 3He(0.82) 1n(2.45) 50 3.27
2D 2D 3T(1.00) 1p(3.03) 50 4.03 2D
3T 4He(3.52) 1n(14.08) 17.6 2D
3He 1p(14.7) 4He(3.7) 18.4 3T 3T
4He(1.24) 1n(5.03) 1n(5.03) 11.3 This
was the first fusion reaction performed in the
laboratory. Work carried out by Oliphant et al.
(1934) One gram of deuterium undergoing the
first 2 (D-D) reactions releases about 1011 J
i.e. roughly 25,000 kWh per gramme mass of the
reacting nuclei (a similar yield to that for the
fission of Uranium). Side reactions (3 and 4)
increase this energy yield by about a factor 5.
8
Fusion Reactions 2/2
Total energy release
(MeV) 3T 3He 1p(5.38) 4He(4.76)
1n(5.38) 51 12.1 3T 3He 2D(9.54)
4He(4.76) 43 14.3 3T 3He 5He(11.9)
1p(2.4) 6 14.3 3He 3He 1p(5.73)
1p(5.73) 4He(1.44) 12.9 1p 6Li 3He(2.3)
4He(1.72) 4.02 3He 6Li 1p(12.4)
4He(2.89) 4He(2.89) 16.09 1p 11B 4He(2.89)
4He(2.89) 4He(2.89) 8.67
9
(No Transcript)
10
The plasma state the fourth state of matter
11
(No Transcript)
12
(No Transcript)
13
How of fusion reactions
Aim Overcome electrostatic repulsion between
like charges
Particle acceleration (eg. Linear accelerator,
pyroelectric crystal, beam-target laser-block,
beam-beam ) Inertial compression (confinement)
(eg. laser target fusion) Catalytic process
(eg. Muon catalysis) Confinement (plasma near
thermal equil) (gravitational, electric, magnetic)
14
The Conditions for Net Fusion Energy Production
1/2
For a steady-state fusion reactor the input power
equals the output power. For net energy
production, the electrical output (after
conversion of the reactor thermal output (Eo) to
electricity with efficiency ?e) must be more
than sufficient to feedback energy (which is
converted at efficiency ?i) to provide the input
energy (Ein) to sustain the reactor. This
condition is ?e?i Eo gt Ein (5.4-1) Now,
let Ec fusion energy from charged-particle
products En fusion energy from neutrons Er
fusion fuel radiation loss Eth fusion thermal
energy (3nkBTV, where V is the volume of
plasma) El fusion fuel energy loss (Eth
Er) For a steady state of the fusion fuel, the
heating input must balance the losses i.e. Ein
Ec El (5.4-2) Assuming that all (the
losses and fusion neutron) energy can be
recovered, then El En Eo (5.4-3)
15
Conditions for Net Fusion Energy Production 2/2
Combining these three equations (5.4-1) to
(5.4-3) to eliminate El, we have Ec En gt
Eing(?) (5.4-4) where g(?) 1/(?e?i) 1.
Now Ec En is the total energy released by
fusion reactions Ef. Using this result (Ef/g(?) gt
Ein) and the definition of El we have Ef/g(?)
Ec - Er gt Eth (5.4-4) Now a fusion
reactor is characterized by an energy confinement
time (i.e. representative of the time it takes
for the energy in the plasma to be lost by
processes other than radiation, if there is no
power input). Let this time be represented by ?.
The plasma power loss (independent of radiation
losses) are then Eth/?. In terms of the
corresponding powers (E/(V?) P), then (5.4-4)
can be expressed as n? gt (3kBT)/?Pf/(g(?)n2)
Pc/(n2) Pr/(n2)? (5.4-5)
16
Conditions for fusion power in confined systems
-
-




T
D

• Achieve sufficiently high
• ion temperature Ti
• ? exceed Coulomb barrier
• density nD ? energy yield
• energy confinement time ?E

?100 million C
Fusion power heat loss f(Ti,nD,?E)
17
Progress in magnetically confined fusion
18
D-T fusion fuels are very abundant
NB 99.9885 of all matter is H
Deuterium
Tritium
Lithium

• According to the DOE (2001), world energy usage
  13.5 TW
• Estimated Earth reserves are 6 x 108 TW
  years of D-T, 2 x 1011 TW years of D-D

T. J. Dolan, Fus. Res., 2000
19
Low level waste, compared to fission
Comparison of fission and fusion radioactivity
after decommissioning
Present ferritic technology allows a reduction of
gt3,000 over 100 years 100 recycling is
possible after 100 years Using future Vanadium
alloy structures, fusion is 1,000,000x less
radioactive after 30 years than fission.
http//fi.neep.wisc.edu http//www.ofes.fusion
.doe.gov
20
(No Transcript)
21
What are Australias energy needs?
Australia is a hot, dry, sparsely-populated,
resource-rich nation

• Our population is 20 million
• - 1.2 growth rate (2006),
• gt10 million live in Sydney, Melbourne, and
  Brisbane

• Our cities and industry are powered by
  large-scale base load supply Erraring power
  station 2.64GW Australias largest power plant

Nearby Tomago Aluminium smelter (Hunter Valley)