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Nuclear Plant
Introduction
Nuclear power plant is also known as the thermal power station in which the source of the heat
is generated from the reactor vessel. A reactor vessel is a type of furnace in which energy is
generated by a controlled-fission chain reaction and it consists of fuel element, control rods
and a neutron moderator. Besides, it is also a closed system, the amount of mass is fixed and
only the energy can be transferred in and out of the wall. There are a few types of nuclear
reactors, the boiling water reactor, pressuried water reactor and li!uid-metal fast-breeder
reactor. The most commonly used in the world is pressuried water reactor "#$%& as shown in
'igure (.
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'igure ( shows a pressuried water reactor "#$%&
Carnot Cycle
)arnot heat cycle is an idealied power production process and can be applied in thepressuried nuclear reactor. 'our reversible processes for an idealied pressuried water
reactor "'igure *&+
(. sothermal heat addition at the absolute temperature T(, from point ( to point *.
*. sothermal heat reection at the absolute temperature T, from point / to 0.
/. sentropic "reversible adiabatic& expansion in the turbine from point * to 0.0. sentropic "reversible adiabatic& compression in the pump from point 0 to (.
'igure * shows the cycle of the nuclear plant
n the nuclear reactor, the fuel elements are usually shaped in thin rods of about (cm in
diameter and contain fissionable nuclei. 1ranium U92235
is a common reactor fuel. n a large
power there may be thousands of fuel elements placed close together, and the entire region of
fuel elements is known as reactor core.
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Pressurized water
$ater flows through the reactor vessel, where the chain reaction heats it to around 300 .
The water needs to stay in li!uid for the power station to work so the water has to be prevent
from boiling which occurs at 100 at ( atmosphere of pressure, the water is pressuried
in the excess of (2 atmospheres so that the boiling point of the water can be increased.
According to the ideal gas law, the formula is,
PV=nRT
3ince the volume of the nuclear reactor is remain constant throughout the process,
P
T=
nR
V=constant
$hen the pressure of a fixed mass of gas is directly proportional to its absolute temperature
and the volume of the gas is kept constant, this is called the 4ay- 5ussac6s law.
By using the formula of 4ay- 5ussac6s law, the boiling point of the pressuried water can be
determined.
P1
T1=
P2
T2
(1105 )Pa(100+273)K
=(1.5105 )Pa
(T+273 )K
(T+273 )=559.5
T=286.5
3ince it is more than (.2 atmospheres, the boiling point must be more than 286.5 .
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Lost neutron
Lost neutron
Lost neutron
Coolant and moderator
$ater is used as the coolant due to its high heat capacity and specific heat capacity, so it can
absorb more heat generated by the nuclear reaction. Besides, it also used as a neutron
moderator.A neutron moderator is a medium that reduces the speed of fast neutrons.Neutrons
release from nuclear fission in the nuclear vessel have very high speeds and must be slowed
greatly by water 7moderation7 to maintain the chain reaction.
'igure / chain reaction in the nuclear vessel
f output power of a reactor is to remain constant, only one neutron from each fission event
must trigger a new fission, as shown in 'igure /. $hen each fission leads to one additional
fission "no more or less& the reactor said to be critical. A reactor normally operates in critical
condition, because it then produces a steady output of energy. The critical condition can be
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controlled by moving the control rods into and out of the reactor core. The control rods contain
element that can absorb the excess neutron.
Nuclear fission in the nuclear vessel.
Nuclear fission is the splitting of a massive nucleus into two less massive fragments. 8uring
this process, a great deal of energy is released in the form of heat energy. n the nuclear vessel,
a heavy atomic nucleus of 1ranium-*/2 is split into two fragments of roughly e!ual mass as
shown as 'igure 0.
'igure 0 shows the e!uation of nuclear fission of 1ranium-*/2
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Besides, the fact that the 1ranium fission reaction releases *.2 neutron, on the average, makes
it possible for a self-sustaining series of fissions to occur and since the reaction is controlled
by moving the control rods into and out of the reactor core, the number of neutron left to
collide and react with another nucleus is reduced to one in order to obtain the critical
condition. 3eeing that there is one neutron left, the reaction will be continued and this is called
the nuclear chain reaction "%efer to 'igure /&. Nuclear chain reactions is a chain reaction that
process in which neutrons released in fission produce an additional fission in at least one
further nucleus. This nucleus in turn produces neutrons, and the process repeats. 'urthermore,
the estimation of energy released during nuclear fission has been calculated as shown below.
'igure 2 shows the binding energy per nucleon graph
The graph above shows that the binding energy of a 1ranium nucleus with A 9 */2 is about
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$here,
m is the mass defect of the nucleus
m1 is the mass of neutrons and protons
m2 is the mass of nucleus
c is the speed of light in the vacuum 2.99792458108
The 1ranium nucleus has >* protons, (0/ neutrons, and has an observed mass of */2.0/>*>>
u.
m1=(mass of proton+mass of neutron) m
1=(921.00727647u )+(1431.00866492u )
m1=236.9085188u
m=m1m
2 m=236.9085188u235.0439299u m=1.8645889u
m=(1.8645889 (1.661027 ))kg m=3.0962221811027 kg
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(.:*:;0:
(.?;;0>*
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Eb=(3.0962221811027) (2.99792458108 )2 Eb 2.8610
10J
Eb (2.861010
J) ( 1eV
1.60221019 J)
1.78eV
Then, finding the binding energy per nucleon,
Binding energy per nuc!eon=(1.78109 )
2357.6"eV per nuc!eon
n the fission product nuclei, the medium binding energy per nucleon amounts to
approximately ?.2
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Binding energy per nuc!eon=(1.14109 )
1408.14"eV per nuc!eon
The %ubidium nucleus has /: protons, 2; neutrons, and has an observed mass of >*.>**0(??
u.
m1=(massof proton+mass of neutron ) m1=(371.00727647u )+(561.00866492 u )
m1=93.75446491u
m=m1m
2 m=93.75446491u92.92204188u m=0.83242303u
m=(0.83242303 (1.661027 ) ) kg m=1.381822231027 kg
Eb=(1.381822231027 ) (2.99792458108 )2 Eb 1.2410
10J
Eb (1.241010
J) ( 1eV1.60221019 J)0.77eV
Then, finding the binding energy per nucleon,
Binding energy per nuc!eon=(0.77109 )
938.28"eV per nuc!eon
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These product nuclei have the binding energy per nucleon amounts to approximately ?.2
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Beta #articles 'rom 'ission #roducts :
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'or )esium- (0
#'
(e58
140
#'
)a
57
140
#'
Ba
56
140
(s55140
'or %ubidium- >/
#'
*b41
93
#'
%r
40
93
#'
+3993
#'
r38
93
Rb37
93
The energy released during the decay for each chain will be e!uivalent to the mass difference
between the original fission product and the sum of the final stable nuclide and the beta
particles emitted.
The energy released in the decay chain of )esium- (0 is calculated below.
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E$ecay=[m(s140( m(e140+3me!ectron) ]( 931.5"eVu )
E$ecay=[139.917282354 u(139.905438706 u+3 (0.00054858u ))(931.5"eV
u )]
E$ecay=(0.010197908 u )( 931.5"eVu ) E$ecay=9.50"eV
The energy released in the decay chain of %ubidium- >/ is calculated below.
E$ecay=[mRb93(m*b93+4me!ectron)](931.5"eV
u )
E$ecay=[92.922041876 u(92.906378058u+4 (0.00054858u ))( 931.5"eVu )]
E$ecay=(0.013469498 u )( 931.5"eVu ) E$ecay=12.55"eV
The total decay energy is the sum of the energies of the two chains is approximately */
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reduces !uickly to a small fraction of its value while operating. The decay heat produced is
significant, however, systems must be provided to keep the reactor cool even after shutdown.
Conservation Of Energy in Nuclear Vessels
This nuclear fission process obeys the conservation laws of physics. 'irst, the conservation of
energy and mass, since the sum of mass and energy is always conserved in a nuclear reaction.
ven though mass changes to energy, the total amount of mass and energy combined remains
the same. Next, conservation of linear momentum, since this !uantity must be conserved in all
inertial frames of reference.
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Conclusion
After explaining on how the heat is generated, the explanation on how electricity is generated
will be continued. 'irst, the reactor coolant pump circulates the hot pressuried water from the
reactor vessel to the steam generator. Dere, the water flows through thousands of looped pipes
before circulating back to the reactor vessel. A second stream of water flows through the steam
generator, around the outside of the pipes. This water is under much less pressure, so the heat
from the pipes boils it into steam. The steam then passes through a series of turbines, causing
them to spin, converting the heat energy produced in the reactor into mechanical energy. Ashaft connects the turbines to a generator, so when the turbines spin, so does the generator. The
generator uses an electromagnetic field to convert this mechanical energy into electrical
energy. A transformer converts the electrical energy from the generator to a high voltage. The
national grid uses high voltages to transmit electricity efficiently through the power lines to
the homes and businesses that need it. Dere, other transformers reduce the voltage back down
to a usable level. After passing through the turbines, the steam comes into contact with pipes
full of cold water pumped in from the sea. ventually, the cold pipes cool the steam so that it
condenses back into water. t is then piped back to the steam generator, where it can be heated
up again, turn into steam again, and keep the turbines turning.
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Biliogra!hy
(. uropean Nuclear 3ociety, / Apr *(2. 7Nuclear 'ission7. =iewed on *( Nov *(2.
Available from+ Ehttps+FFwww.euronuclear.orgFinfoFencyclopediaFnFnuclear-
fission.htmG.*. %. Nave, *(0. HNuclear Binding nergyI. =iewed on *( November *(2. Available
from+ Ehttp+FFhyperphysics.phy-astr.gsu.eduFhbaseFnuceneFnucbin.htmlG
/. #hysics Net, *(*. H
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(*. %. Nave, *(0. H$ater as thedition. Kohn $iley : 3ons 3ingapore
#te. 5td.
(;. 'oo 3eng Teek, *(/. 3uccess physics 3#