Power Plant Engineering

particles is small compared with that of y-rays but is larger than that of a particles. 6- and a-particle
decay are usually accompanied by the emission of y radiation.
Gamma radiation. This is electromagnetic radiation of extremely short wavelength and very
high frequency and therefore high energy. 
γ
-rays and X-rays are physically similar but differ in their
origin and energy: 
γ
-rays from the nucleus, and X-rays from the atom because of orbital electrons chang-
ing orbits or energy levels. Gamma wave-lengths are, on an average, about one-tenth those of X-rays,
although the energy ranges overlap somewhat. Gamma decay does not alter either the atomic or mass
numbers.
100
80
60
40
20
0
0
2
0
40
60
80
100
120
140
160
Atomic number Z
N
eut
ron n
u
m
ber
N
Ma
ss
nu
mb
er 
A
240
220
200
180
160
140
120
100
80
60
40
20
De
c
a
y
s
c
hene
β
–
β
+
α
Z –
N
Fig. 10.5. Z-N Chart.

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322
POWER PLANT ENGINEERING
10.10 NUCLEAR REACTOR
10.10.1 PARTS OF A NUCLEAR REACTOR
A nuclear reactor is an apparatus in which heat is produced due to nuclear fission chain reaction.
Fig. 10.6 shows the various parts of reactor, which are as follows :
1. Nuclear Fuel
2. Moderator
3. Control Rods
4. Reflector
5. Reactors Vessel
6. Biological Shielding
7. Coolant.
Fig. 10.6 shows a schematic diagram of nuclear reactor.
Control Rod
Fuel
Rods
Reflector
Moderator
Pressure
Vessel
Concrete
Shielding
Coolant
Coolant