Download Lecture 1.

Nuclear
Power
Plants
Dr. Ervin Rácz, Ph.D.
associate professor
Motivating factors
1)
It is positive, if the graduating electric engineers (or engineers) have
knowledge about wide spectrum of power plants  nuclear power
plants are part of wide spectrum of power plant
knowledge transfer of nuclear power plants at Power System
Department was missing so far
2)
There are articles published about operation and/or failures of nuclear
power plants in the media. Widen knowledge about nuclear
technology helps the civilian persons to understand and see clearly the
given news.
3)
Forever questions:
o
It is good or bad using nuclear power plants? Do we need or do not
need nuclear power plants?
o
Should we prefer or do not prefer energy generation based on
nuclear power plants?
o
What are advantages? What are disadvantages of using nuclear
power plants?
4)
You might be decision makers in nuclear topics in your working place in
the (near) future 
o
You must balance correct, exact, precise information
o
Knowledge is needed to take decision!
Lecture #1.
Motivating factors
5) Energetics concept of the Hungarian Government for the near
future:
o New energy law
What is the source
of the electric current?
Renewable:
Nuclear
energy:
According to the current plans,
our Government plans to cover the
significant part of the energy used
in Hungary using nuclear power
plant(s) working within the borders
of Hungary.
Nuclear power reactors will
generate significant part of electric
energy for Hungarians.
Coal:
Oil:
Natural gas:
Import:
Source: Ministry of National Development
Lecture #1.
Energy generated by burning of coil
and oil will be decreased in the
future..
Hungarian Government decided:
- Lifetime extension and modernization of
Paks I. Power Plant
- Extension of Paks I.  Paks II. project.
Topics
1.
2.
3.
4.
5.
Elements of Nuclear Physics
Detecting nuclear radiations, radiation detectors
History of Nuclear Physics; Beginning of Nuclear
A Nuclear Power Plant
Types of Nuclear Reactors based on usage of the
reactors
6. Generations of Nuclear Power
7. Nuclear Reactors in Hungary
8. Mini or small Nuclear Power Plants
9. Reactor Safety, Radiation Safety
10. Nuclear Accidents, abnormal operations
11. Nuclear Power plants and Environmental Protection
12. Fusion, Fusion Devices, Fusion Power Plants
13. Natural nuclear reactors or Nuclear Reactors in the
Nature
Lecture #1.
Elements of
Nuclear Physics
Chapter 1.
Lecture #1.
Structure of a Nucleus
1.
Henry Antoine Becquerel
(1852 – 1908):
o
1898: experimental investigation of
radiation of uranium pitchblende
o
Packaged uranium pitchblende
leaved on a photopaper
o
Checking the photopaper great
trace on the paper
o
Intensity of the radiation was
proportional to the strength of the
observed shadow
o
Radiation originated from the
uranium pitchblende propagates
spontaneously.  new name:
o
Lecture #1.
nuclear radiation (radioactive)
1903: Nobel price in Physics
Generation of X-rays
Generation of x-rays
Source: http://www.hitachi-hightech.com/global/products/science/tech/ana/xrf/descriptions/index.html/
Lecture #1.
Structure of a Nucleus
2. Marie Sklodowska Curie
(1867 - 1934) és
Pierre Curie (1859 – 1906)
o Two new elements came
out from uranium
pitchblende
radium and polonium
o They radiate stronger then
the uranium pitchblende
itself
o New elements:
radium and polonium
Lecture #1.
Structure of a Nucleus
• Thomson 1897:
o Plum-pudding model of an
atom
o In the globally natural atom
(like in a sphere) the
positive charge distribute
uniformly.
o Electrons sit in the uniform
positive material, like plums
in pudding or raisins in a
scone
„pudding”– positive
charged part
„plums or raisins” – negative
electrons
Lecture #1.
Rutherford Scattering Experiment
Geiger – Marsden Experiment
•
•
•
•
University on Manchester
1909 – 1911
Hans Geiger, Ernest Marsden
Leading by Prof. Ernest Rutherford
•
In order to investigate of the structure of
Gold some scattering experiments were
designed and ran
Gold foil is bombed by alpha particles
(=nucleus of Helium)
•
Lecture #1.
•
Expected results:
- alpha particles will slow down
- alpha particles will keep direction of its
propagation
- alpha particles penetrate through the
gold foil
- alpha particles will heat the detector
surface directly behind the gold foil target
•
Real results:
- direction of the propagating alpha
particles has been changed after the
collision with gold
- alpha radiation backscattering was
observed (deflected radiation)
Rutherford Scattering Experiment
Geiger–Marsden Experiment
• Explanation:
Lecture #1.
o If the structure of Gold atom
would work according to the
plum pudding model, than the
backscattering (deflecting) of
alpha particles cannot be
observed. Particles would slow
down keeping their direction.
o Propagation of alpha particles
deflected  the plum pudding
model cannot be valid.
o Heavy and positively charged
local scattering centers have
to be presented inside the
atom
o The atom has nucleus. The
nucleus is positively charged.
The nucleus has big mass.
Structure of a Nucleus
3. Sir Ernest Rutherford
(1871 - 1937)
• Scattering experiment
o Nucleus of an atom exists or
in other words there is
nucleus of an atom!
o Size of a nucleus can be
predicted from the
scattering angle of the
alpha-particles.
o Size of a nucleus: 2R,
o Taking into account the
size, the radius of a nucleus
is: R
Lecture #1.
Radius of a Nucleus
• Definition (radius of a nucleus):
Radius of a nucleus can be characterized by the size of the
charge distribution inside the nucleus. In other words, the
radius starts in the center of a nucleus and ends at the
edge of the impact area of forces acting inside the
nucleus. Symbol: R
• Formula of the radius
of the nucleus:
𝑅 = 𝑅0 ∙ 𝐴1/3
𝑅0 = 1,2 𝑓𝑚 𝑓𝑒𝑚𝑡𝑜𝑚𝑒𝑡𝑒𝑟 , 1 𝑓𝑚 = 10−15 𝑚
In the atomic physics: 1 fermi means: 1 fm = 1 fermi
𝐴 = 𝑚𝑎𝑠𝑠 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑎𝑛 𝑎𝑡𝑜𝑚
Lecture #1.
??
What is this?
Charge of Nucleus, Mass of an Atom
• Antonius Johannes van den Broek (1870 - 1926):
o 1913: Charge of nucleus comes out as the multiplication
of the charge unit and the atomic number (of an atom).
• Francis William Aston (1877 - 1945):
o 1919: Mass of an atom is always proportional to an atomic
mass unit (AMU) multiplicated by a positive integer
(it came out from mass-spectrometer measurements lead by
Aston)
o The atomic mass unit was higher than the electron mass.
It was comparable to the mass of the ground state
Hydrogen atom.
o Mass of an atom can be characterized by the atomic mass.
Symbol: A (it is called after Aston)
•
Definition (atomic mass unit, AMU):
o A1
o later: 1/12 part of the mass of the ground state carbon atom
12
C. In other words:
o 1 𝐴𝑀𝑈 = 931,5
Lecture #1.
𝑀𝑒𝑉
𝑐2
= 1,6603 ∙ 10−27 𝑘𝑔
AMU, Mass Number of an Atom
The atomic mass unit, AMU:
𝑀𝑒𝑉
1 𝐴𝑀𝑈 = 931,5 2 = 1,6603 ∙ 10−27 𝑘𝑔
𝑐
Mass of one proton : 𝑚𝑝 = 1,007 𝐴𝑀𝑈
Definition (mass number of an atom):
The mass number of an atom (signed by A) is the atomic mass which is
rounded to integer numbers and denoted by atomic mass unit.
For proton and Hydrogen: Ap = AH = 1
Definition (signed the chemical elements):
In order to show the chemical elements, we use the following form:
Lecture #1.
A: mass number
Z: proton number
X: chemical symbol
A
X
Z
Mass Density of a Nucleus
• Taking the nucleus as a sphere, the volume: 𝑉 =
4 3
𝑅 𝜋
3
• The radius of a nucleus is (see it before): 𝑅 = 𝑅0 𝐴1/3 ,
so 𝑅3 = 𝑅0 3 𝐴 , It means that 𝑉 =
• Mass density of a nucleus:
4
𝑅0 3 𝐴
3
𝜋.
𝑚
𝐴
3𝐴
3
𝜌=
= =
=
3
𝑉
𝑉
4𝑅0 𝐴𝜋
4𝑅0 3 𝜋
• For example: if 𝑅0 = 1,2 𝑓𝑚, 𝑡ℎ𝑒𝑛 𝜌 = 2,3 ∙ 1017
𝑘𝑔
𝑚3
• Consequence:
Mass density of a nucleus is independent of the mass
number (A).
Lecture #1.
Parts of a Nucleus
• At the beginning of XX. century: Nucleus consists protons only.
• But: 𝐴 ≈ 2𝑍.  The nucleus cannot hold protons only,
because this way the nucleus cannot be electrically natural.
• Suppose of Rutherford: the nucleus holds electrons, too.
This contradicts to the Heisenberg inequality proof.
• James Chadwick (1891 - 1974):
o 1932: discovery of a new particle: neutron .
• Werner Karl Heisenberg (1901 - 1976) and
Igor Yevgenyevics Tamm (1895 - 1971)
o They found the neutron in the nucleus
o Theory of: Nucleus consists of protons and
neutrons
Lecture #1.
Definitions
• Definition (nucleon):
Protons and neutrons consist the nucleus calls as
nucleon. We use to sign the number of nucleons by N.
• Consequence:
The mass number of an atom can be defined by the
number of nucleons of the nucleus. As it is given here:
A=Z+N
• Definition (isotopes):
Nuclei with same proton numbers but different mass
numbers are isotopes.
• Definition (isobars):
Nuclei with same mass numbers but different proton
numbers are isobars.
• Definition (isotones):
Nuclei with same neutron numbers use to call as
isotones.
Lecture #1.
Map of Isotopes
•
•
•
Map of nuclei
Small squares symbolize the
nuclei
Stable nuclei: black squares
•
Close to the stable nuclei: nuclei
with longer half-life
Far from stable nuclei:
nuclei with fast decay
•
Proton drop-off line (it is the
upper border of nuclei with fast
decay. Above of it the nucleus
emits proton(s) to get
energetically more stable
position. Above of the proton
drop-off line the nuclei are not
stable, but they emit protons
immediately.
•
Neutron drop-off line ( it is the
lower border of nuclei with fast
decay). The nuclei do not exist
here, because the nucleus emits
a neutron immediately.
Lecture #1.
Momenta of Nuclei
•
•
•
•
Definition (spin of nucleus):
Net of the angular momentum (spin) and the orbital angular
momentum of the nucleus is called as spin of the nucleus.
Nuclei have spin with half-number.
ℎ
The spin of nucleus can be written as: s=n , where n is integer or
2𝜋
half-number
Definition (Bohr-magneton):
Quantum of the magnetic dipole momentum of an electron
inside an atom calls as Bohr-magneton.
𝑒
ℎ
𝑀𝐵 =
∙
2𝑚𝑒 2𝜋
•
Definition (magneton of nucleus):
Quantum of the magnetic dipole momentum of a proton inside
an atomic nucleus calls as magneton of nucleus:
𝑀𝐵𝑚
Lecture #1.
𝑒
ℎ
=
∙
2𝑚𝑝 2𝜋
Forces inside Nucleus = Nuclear Force
•
•
•
•
Problem:
Many protons stay together inside a small nucleus. Electric forces
do not destroy the nucleus. Why?? The protons do not scatter into
the space. Why??
Conclusion:
Due to the nucleus exists and the nucleus stays in one volume,
there must be a force which stick the protons together.
Definition (force inside nucleus = nuclear force):
The force which acts in between nucleons (inside nucleus) use to
call as nuclear force. It is a very intense force but it has a very
short range inside nucleus only. Nuclear forces are independent
of charges of charged particles. The nuclear force is the same in
between two protons and in between two neutrons.
Introduced by Hideki Yukawa (1907 - 1981):
o 1935: pion: In order to describe the forces in
between nucleons.
o -meson or pion are „messengers” or
„intermediary particles” between two nucleons.
o Nuclear force is described by -mesons or pions.
Lecture #1.
Nuclear Forces
• Nucleons are not simple but complex particles.
(Quarks, gluons)
• Definition (strong interaction):
The interaction in between nucleons use to call as strong
interaction. This interaction sticks the nucleons together.
Lecture #1.
Simple Models of a Nucleus
1. Bonding energy:
o
Definition (bonding energy):
Bonding energy is the energy of 𝐸𝑏 what is released when the nucleus
is being built from its nuclear components.
It means that: Z pieces of protons, N pieces of neutrons separately 
𝐸𝑏  nucleus in one.
Where 𝑚 is the mass of the nucleus, 𝑐 is the speed of light in vacuum:
𝐸𝑏 = 𝑍𝑚𝑝 + 𝑁𝑚𝑛 − 𝑚 𝑐 2
o
Definition (bonding energy for one single nucleon):
𝜀𝑏 =
•
•
𝐸𝑏
𝐴
It gives information how the nucleon is bonded in the nucleus.
It can be measured precisely by mass spectrometry.
Lecture #1.
Simple Models of a Nucleus
Lecture #1.
1. előadás
ΔE/A (bonded energy fells for one single nucleon, [MeV])
Simple Models of a Nucleus
A (Mass number = number of nucleons in a nucleus)
Lecture #1.
Averaged bonded energy for one single nucleus
in function of the mass number (A)
Lecture #1.
Simple Models of a Nucleus
2.
Liquid drop model (developed by Weizsäcker):
o
basics:
•
Properties of sizes on nucleus 
mass density of a nucleus is constant (see it before)
•
The nucleus can be taken into account as incompressible liquid
•
The nuclei can be taken as many of small size balls with same
radii and they are colliding each other
•
Bonded energy  nuclear forces are saturated,
nucleons can interact with neighboring nucleons
Definition (liquid drop model) :
The nucleus cannot be compressed, it has electric charge. The
nucleus can be taken into account as fluid with electric charge and
its surface is minimized (surface tension).
o
Comment:
•
Using the liquid drop model a semi-empiric bonded formula has
been described.
•
The semi-empiric formula describes the bonded energies of the
nuclei quiet well.  good, usable model !
•
The liquid drop model does not describe the exotic nucleii good.
In other words, the model cannot be used for describing exotic
nuclei.
Lecture #1.
o
Simple Models of a Nucleus
3. Shell model for nucleus:
o
About the shell model:
•
The shell model is the application of the quantum mechanics
for nuclei.
•
Potential acts in between the particles of the system must be
used very well. Interaction between protons and neutrons is
not well known  difficult to describe
•
Mean-field approximation:
 Let us take that:
Every nucleon moves in the same averaged potential
field of the nucleus, and the averaged potential field of
the nucleus is spherical.
 Main task is the calculate wave functions for the nucleus.
Lecture #1.