Power Plant Engineering

particle itself. The importance of neutri-
nos is that they carry some 5 percent of the total energy produced in fission. This energy is completely
react lost because neutrinos do not rea and are not stopped by any practical structural material. The
neutrino is given the symbol u.
There are many other atomic sub particles. An example is the mesons, unstable positive, nega-
tive, or neutral particles that have masses intermediate between an electron and a proton. They are
exchanged between nucleons and are thought to account for the forces between them. A discussion of
these and other sub particles is, however beyond the scope of this book.
Electrons that orbit in the outermost shell of an atom are called valence electron. The outermost
shell is called the valence shell. Thus, hydrogen has one valence electron and its K shell is the valence

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POWER PLANT ENGINEERING
shell, etc. Chemical properties of an element are function of the number of valence electrons. The
electrons play little or not part nuclear interactions.
e
n
p
( )
d
e
n
p
e
e
( )
c
n
p
e
e
( )
b
p
e
( )
a
e
p
n
( )
e
( )
f
e
15
p
16
n
( )
g
54
p
71
n
e
 Fig. 10.2
10.4 SUMMARY OF NUCLEAR ENERGY CONCEPTS AND TERMS
10.4.1 SUMMARY OF FEATURES
1. Heat energy source is fission of radioactive material, (U-235)
2. Two typical plant designs:
Pressurized water reactor (PWR) (U.S.)
Boiling water reactor (BWR) (Russian)
3. Fuel pellets are in a large number of tubes (fuel rods)
4. Water circulates through core
5. Water converted to steam drives turbine
6. Turbine turns generator 
→
electricity
10.4.2 FISSION
Unstable (radioactive) elements spontaneously split (radioactive decay), emitting high energy
particles. Collision of particles with other atomic nuclei can trigger further nuclear decompositions. A
small amount of mass is converted into a large amount of energy, when atomic nuclei are split.
Einstein equation: E = mc
2
Conversion of mass to energy. E = energy, m = mass converted, c = speed of light

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NUCLEAR POWER PLANT
315